asfgit closed pull request #6456: [FLINK-9947] [docs] Document unified table sources/sinks/formats URL: https://github.com/apache/flink/pull/6456
This is a PR merged from a forked repository. As GitHub hides the original diff on merge, it is displayed below for the sake of provenance: As this is a foreign pull request (from a fork), the diff is supplied below (as it won't show otherwise due to GitHub magic): diff --git a/docs/dev/table/connect.md b/docs/dev/table/connect.md new file mode 100644 index 00000000000..fa51783a590 --- /dev/null +++ b/docs/dev/table/connect.md @@ -0,0 +1,1049 @@ +--- +title: "Connect to External Systems" +nav-parent_id: tableapi +nav-pos: 19 +--- +<!-- +Licensed to the Apache Software Foundation (ASF) under one +or more contributor license agreements. See the NOTICE file +distributed with this work for additional information +regarding copyright ownership. The ASF licenses this file +to you under the Apache License, Version 2.0 (the +"License"); you may not use this file except in compliance +with the License. You may obtain a copy of the License at + + http://www.apache.org/licenses/LICENSE-2.0 + +Unless required by applicable law or agreed to in writing, +software distributed under the License is distributed on an +"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +KIND, either express or implied. See the License for the +specific language governing permissions and limitations +under the License. +--> + +Flink's Table API & SQL programs can be connected to other external systems for reading and writing both batch and streaming tables. A table source provides access to data which is stored in external systems (such as a database, key-value store, message queue, or file system). A table sink emits a table to an external storage system. Depending on the type of source and sink, they support different formats such as CSV, Parquet, or ORC. + +This page describes how to declare built-in table sources and/or table sinks and register them in Flink. After a source or sink has been registered, it can be accessed by Table API & SQL statements. + +<span class="label label-danger">Attention</span> If you want to implement your own *custom* table source or sink, have a look at the [user-defined sources & sinks page](sourceSinks.html). + +* This will be replaced by the TOC +{:toc} + +Dependencies +------------ + +The following table list all available connectors and formats. Their mutual compatibility is tagged in the corresponding sections for [table connectors](connect.html#table-connectors) and [table formats](connect.html#table-formats). The following table provides dependency information for both projects using a build automation tool (such as Maven or SBT) and SQL Client with SQL JAR bundles. + +{% if site.is_stable %} + +### Connectors + +| Name | Version | Maven dependency | SQL Client JAR | +| :---------------- | :------------ | :--------------------------- | :----------------------| +| Filesystem | | Built-in | Built-in | +| Apache Kafka | 0.8 | `flink-connector-kafka-0.8` | Not available | +| Apache Kafka | 0.9 | `flink-connector-kafka-0.9` | [Download](http://central.maven.org/maven2/org/apache/flink/flink-connector-kafka-0.9{{site.scala_version_suffix}}/{{site.version}}/flink-connector-kafka-0.9{{site.scala_version_suffix}}-{{site.version}}-sql-jar.jar) | +| Apache Kafka | 0.10 | `flink-connector-kafka-0.10` | [Download](http://central.maven.org/maven2/org/apache/flink/flink-connector-kafka-0.10{{site.scala_version_suffix}}/{{site.version}}/flink-connector-kafka-0.10{{site.scala_version_suffix}}-{{site.version}}-sql-jar.jar) | +| Apache Kafka | 0.11 | `flink-connector-kafka-0.11` | [Download](http://central.maven.org/maven2/org/apache/flink/flink-connector-kafka-0.11{{site.scala_version_suffix}}/{{site.version}}/flink-connector-kafka-0.11{{site.scala_version_suffix}}-{{site.version}}-sql-jar.jar) | + +### Formats + +| Name | Maven dependency | SQL Client JAR | +| :---------------- | :--------------------------- | :--------------------- | +| CSV | Built-in | Built-in | +| JSON | `flink-json` | [Download](http://central.maven.org/maven2/org/apache/flink/flink-json/{{site.version}}/flink-json-{{site.version}}-sql-jar.jar) | +| Apache Avro | `flink-avro` | [Download](http://central.maven.org/maven2/org/apache/flink/flink-avro/{{site.version}}/flink-avro-{{site.version}}-sql-jar.jar) | + +{% else %} + +This table is only available for stable releases. + +{% endif %} + +{% top %} + +Overview +-------- + +Beginning from Flink 1.6, the declaration of a connection to an external system is separated from the actual implementation. + +Connections can be specified either + +- **programmatically** using a `Descriptor` under `org.apache.flink.table.descriptors` for Table & SQL API +- or **declaratively** via [YAML configuration files](http://yaml.org/) for the SQL Client. + +This allows not only for better unification of APIs and SQL Client but also for better extensibility in case of [custom implementations](sourceSinks.html) without changing the actual declaration. + +Every declaration is similar to a SQL `CREATE TABLE` statement. One can define the name of the table, the schema of the table, a connector, and a data format upfront for connecting to an external system. + +The **connector** describes the external system that stores the data of a table. Storage systems such as [Apacha Kafka](http://kafka.apache.org/) or a regular file system can be declared here. The connector might already provide a fixed format with fields and schema. + +Some systems support different **data formats**. For example, a table that is stored in Kafka or in files can encode its rows with CSV, JSON, or Avro. A database connector might need the table schema here. Whether or not a storage system requires the definition of a format, is documented for every [connector](connect.html#table-connectors). Different systems also require different [types of formats](connect.html#table-formats) (e.g., column-oriented formats vs. row-oriented formats). The documentation states which format types and connectors are compatible. + +The **table schema** defines the schema of a table that is exposed to SQL queries. It describes how a source maps the data format to the table schema and a sink vice versa. The schema has access to fields defined by the connector or format. It can use one or more fields for extracting or inserting [time attributes](streaming.html#time-attributes). If input fields have no determinstic field order, the schema clearly defines field names, their order, and origin. + +The subsequent sections will cover each definition part ([connector](connect.html#table-connectors), [format](connect.html#table-formats), and [schema](connect.html#table-schema)) in more detail. The following example shows how to pass them: + +<div class="codetabs" markdown="1"> +<div data-lang="Java/Scala" markdown="1"> +{% highlight java %} +tableEnvironment + .connect(...) + .withFormat(...) + .withSchema(...) + .inAppendMode() + .registerTableSource("MyTable") +{% endhighlight %} +</div> + +<div data-lang="YAML" markdown="1"> +{% highlight yaml %} +name: MyTable +type: source +update-mode: append +connector: ... +format: ... +schema: ... +{% endhighlight %} +</div> +</div> + +The table's type (`source`, `sink`, or `both`) determines how a table is registered. In case of table type `both`, both a table source and table sink are registered under the same name. Logically, this means that we can both read and write to such a table similarly to a table in a regular DBMS. + +For streaming queries, an [update mode](connect.html#update-mode) declares how to communicate between a dynamic table and the storage system for continous queries. + +The following code shows a full example of how to connect to Kafka for reading Avro records. + +<div class="codetabs" markdown="1"> +<div data-lang="Java/Scala" markdown="1"> +{% highlight java %} +tableEnvironment + // declare the external system to connect to + .connect( + new Kafka() + .version("0.10") + .topic("test-input") + .startFromEarliest() + .property("zookeeper.connect", "localhost:2181") + .property("bootstrap.servers", "localhost:9092") + ) + + // declare a format for this system + .withFormat( + new Avro() + .avroSchema( + "{" + + " \"namespace\": \"org.myorganization\"," + + " \"type\": \"record\"," + + " \"name\": \"UserMessage\"," + + " \"fields\": [" + + " {\"name\": \"timestamp\", \"type\": \"string\"}," + + " {\"name\": \"user\", \"type\": \"long\"}," + + " {\"name\": \"message\", \"type\": [\"string\", \"null\"]}" + + " ]" + + "}" + + ) + ) + + // declare the schema of the table + .withSchema( + new Schema() + .field("rowtime", Types.SQL_TIMESTAMP) + .rowtime(new Rowtime() + .timestampsFromField("ts") + .watermarksPeriodicBounded(60000) + ) + .field("user", Types.LONG) + .field("message", Types.STRING) + ) + + // specify the update-mode for streaming tables + .inAppendMode() + + // register as source, sink, or both and under a name + .registerTableSource("MyUserTable"); +{% endhighlight %} +</div> + +<div data-lang="YAML" markdown="1"> +{% highlight yaml %} +tables: + - name: MyUserTable # name the new table + type: source # declare if the table should be "source", "sink", or "both" + update-mode: append # specify the update-mode for streaming tables + + # declare the external system to connect to + connector: + type: kafka + version: "0.10" + topic: test-input + startup-mode: earliest-offset + properties: + - key: zookeeper.connect + value: localhost:2181 + - key: bootstrap.servers + value: localhost:9092 + + # declare a format for this system + format: + type: avro + avro-schema: > + { + "namespace": "org.myorganization", + "type": "record", + "name": "UserMessage", + "fields": [ + {"name": "ts", "type": "string"}, + {"name": "user", "type": "long"}, + {"name": "message", "type": ["string", "null"]} + ] + } + + # declare the schema of the table + schema: + - name: rowtime + type: TIMESTAMP + rowtime: + timestamps: + type: from-field + from: ts + watermarks: + type: periodic-bounded + delay: "60000" + - name: user + type: BIGINT + - name: message + type: VARCHAR +{% endhighlight %} +</div> +</div> + +In both ways the desired connection properties are converted into normalized, string-based key-value pairs. So-called [table factories](sourceSinks.html#define-a-tablefactory) create configured table sources, table sinks, and corresponding formats from the key-value pairs. All table factories that can be found via Java's [Service Provider Interfaces (SPI)](https://docs.oracle.com/javase/tutorial/sound/SPI-intro.html) are taken into account when searching for exactly-one matching table factory. + +If no factory can be found or multiple factories match for the given properties, an exception will be thrown with additional information about considered factories and supported properties. + +{% top %} + +Table Schema +------------ + +The table schema defines the names and types of columns similar to the column definitions of a SQL `CREATE TABLE` statement. In addition, one can specify how columns are mapped from and to fields of the format in which the table data is encoded. The origin of a field might be important if the name of the column should differ from the input/output format. For instance, a column `user_name` should reference the field `$$-user-name` from a JSON format. Additionally, the schema is needed to map column names and types from an external system to Flink's representation. In case of a table sink, it ensures that only data with valid schema is written to an external system. + +The following example shows a simple schema without time attributes and one-to-one field mapping of input/output to table columns. + +<div class="codetabs" markdown="1"> +<div data-lang="Java/Scala" markdown="1"> +{% highlight java %} +.withSchema( + new Schema() + .field("MyField1", Types.INT) // required: specify the fields of the table (in this order) + .field("MyField2", Types.STRING) + .field("MyField3", Types.BOOLEAN) +) +{% endhighlight %} +</div> + +<div data-lang="YAML" markdown="1"> +{% highlight yaml %} +schema: + - name: MyField1 # required: specify the fields of the table (in this order) + type: INT + - name: MyField2 + type: VARCHAR + - name: MyField3 + type: BOOLEAN +{% endhighlight %} +</div> +</div> + +For *each field*, the following properties can be declared in addition to the column's name and type: + +<div class="codetabs" markdown="1"> +<div data-lang="Java/Scala" markdown="1"> +{% highlight java %} +.withSchema( + new Schema() + .field("MyField1", Types.SQL_TIMESTAMP) + .proctime() // optional: declares this field as a processing-time attribute + .field("MyField2", Types.SQL_TIMESTAMP) + .rowtime(...) // optional: declares this field as a event-time attribute + .field("MyField3", Types.BOOLEAN) + .from("mf3") // optional: original field in the input that is referenced/aliased by this field +) +{% endhighlight %} +</div> + +<div data-lang="YAML" markdown="1"> +{% highlight yaml %} +schema: + - name: MyField1 + type: TIMESTAMP + proctime: true # optional: boolean flag whether this field should be a processing-time attribute + - name: MyField2 + type: TIMESTAMP + rowtime: ... # optional: wether this field should be a event-time attribute + - name: MyField3 + type: BOOLEAN + from: mf3 # optional: original field in the input that is referenced/aliased by this field +{% endhighlight %} +</div> +</div> + +Time attributes are essential when working with unbounded streaming tables. Therefore both processing-time and event-time (also known as "rowtime") attributes can be defined as part of the schema. + +For more information about time handling in Flink and especially event-time, we recommend the general [event-time section](streaming.html#time-attributes). + +### Rowtime Attributes + +In order to control the event-time behavior for tables, Flink provides predefined timestamp extractors and watermark strategies. + +The following timestamp extractors are supported: + +<div class="codetabs" markdown="1"> +<div data-lang="Java/Scala" markdown="1"> +{% highlight java %} +// Converts an existing LONG or SQL_TIMESTAMP field in the input into the rowtime attribute. +.rowtime( + new Rowtime() + .timestampsFromField("ts_field") // required: original field name in the input +) + +// Converts the assigned timestamps from a DataStream API record into the rowtime attribute +// and thus preserves the assigned timestamps from the source. +// This requires a source that assigns timestamps (e.g., Kafka 0.10+). +.rowtime( + new Rowtime() + .timestampsFromSource() +) + +// Sets a custom timestamp extractor to be used for the rowtime attribute. +// The extractor must extend `org.apache.flink.table.sources.tsextractors.TimestampExtractor`. +.rowtime( + new Rowtime() + .timestampsFromExtractor(...) +) +{% endhighlight %} +</div> + +<div data-lang="YAML" markdown="1"> +{% highlight yaml %} +# Converts an existing BIGINT or TIMESTAMP field in the input into the rowtime attribute. +rowtime: + timestamps: + type: from-field + from: "ts_field" # required: original field name in the input + +# Converts the assigned timestamps from a DataStream API record into the rowtime attribute +# and thus preserves the assigned timestamps from the source. +rowtime: + timestamps: + type: from-source +{% endhighlight %} +</div> +</div> + +The following watermark strategies are supported: + +<div class="codetabs" markdown="1"> +<div data-lang="Java/Scala" markdown="1"> +{% highlight java %} +// Sets a watermark strategy for ascending rowtime attributes. Emits a watermark of the maximum +// observed timestamp so far minus 1. Rows that have a timestamp equal to the max timestamp +// are not late. +.rowtime( + new Rowtime() + .watermarksPeriodicAscending() +) + +// Sets a built-in watermark strategy for rowtime attributes which are out-of-order by a bounded time interval. +// Emits watermarks which are the maximum observed timestamp minus the specified delay. +.rowtime( + new Rowtime() + .watermarksPeriodicBounded(2000) // delay in milliseconds +) + +// Sets a built-in watermark strategy which indicates the watermarks should be preserved from the +// underlying DataStream API and thus preserves the assigned watermarks from the source. +.rowtime( + new Rowtime() + .watermarksFromSource() +) +{% endhighlight %} +</div> + +<div data-lang="YAML" markdown="1"> +{% highlight yaml %} +# Sets a watermark strategy for ascending rowtime attributes. Emits a watermark of the maximum +# observed timestamp so far minus 1. Rows that have a timestamp equal to the max timestamp +# are not late. +rowtime: + watermarks: + type: periodic-ascending + +# Sets a built-in watermark strategy for rowtime attributes which are out-of-order by a bounded time interval. +# Emits watermarks which are the maximum observed timestamp minus the specified delay. +rowtime: + watermarks: + type: periodic-bounded + delay: ... # required: delay in milliseconds + +# Sets a built-in watermark strategy which indicates the watermarks should be preserved from the +# underlying DataStream API and thus preserves the assigned watermarks from the source. +rowtime: + watermarks: + type: from-source +{% endhighlight %} +</div> +</div> + +Make sure to always declare both timestamps and watermarks. Watermarks are required for triggering time-based operations. + +### Type Strings + +Because type information is only available in a programming language, the following type strings are supported for being defined in a YAML file: + +{% highlight yaml %} +VARCHAR +BOOLEAN +TINYINT +SMALLINT +INT +BIGINT +FLOAT +DOUBLE +DECIMAL +DATE +TIME +TIMESTAMP +ROW(fieldtype, ...) # unnamed row; e.g. ROW(VARCHAR, INT) that is mapped to Flink's RowTypeInfo + # with indexed fields names f0, f1, ... +ROW(fieldname fieldtype, ...) # named row; e.g., ROW(myField VARCHAR, myOtherField INT) that + # is mapped to Flink's RowTypeInfo +POJO(class) # e.g., POJO(org.mycompany.MyPojoClass) that is mapped to Flink's PojoTypeInfo +ANY(class) # e.g., ANY(org.mycompany.MyClass) that is mapped to Flink's GenericTypeInfo +ANY(class, serialized) # used for type information that is not supported by Flink's Table & SQL API +{% endhighlight %} + +{% top %} + +Update Modes +------------ + +For streaming queries, it is required to declare how to perform the [conversion between a dynamic table and an external connector](streaming.html#dynamic-tables--continuous-queries). The *update mode* specifies which kind of messages should be exchanged with the external system: + +**Append Mode:** In append mode, a dynamic table and an external connector only exchange INSERT messages. + +**Retract Mode:** In retract mode, a dynamic table and an external connector exchange ADD and RETRACT messages. An INSERT change is encoded as an ADD message, a DELETE change as a RETRACT message, and an UPDATE change as a RETRACT message for the updated (previous) row and an ADD message for the updating (new) row. In this mode, a key must not be defined as opposed to upsert mode. However, every update consists of two messages which is less efficient. + +**Upsert Mode:** In upsert mode, a dynamic table and an external connector exchange UPSERT and DELETE messages. This mode requires a (possibly composite) unique key by which updates can be propagated. The external connector needs to be aware of the unique key attribute in order to apply messages correctly. INSERT and UPDATE changes are encoded as UPSERT messages. DELETE changes as DELETE messages. The main difference to a retract stream is that UPDATE changes are encoded with a single message and are therefore more efficient. + +<span class="label label-danger">Attention</span> The documentation of each connector states which update modes are supported. + +<div class="codetabs" markdown="1"> +<div data-lang="Java/Scala" markdown="1"> +{% highlight java %} +.connect(...) + .inAppendMode() // otherwise: inUpsertMode() or inRetractMode() +{% endhighlight %} +</div> + +<div data-lang="YAML" markdown="1"> +{% highlight yaml %} +tables: + - name: ... + update-mode: append # otherwise: "retract" or "upsert" +{% endhighlight %} +</div> +</div> + +See also the [general streaming concepts documentation](streaming.html#dynamic-tables--continuous-queries) for more information. + +{% top %} + +Table Connectors +---------------- + +Flink provides a set of connectors for connecting to external systems. + +Please note that not all connectors are available in both batch and streaming yet. Furthermore, not every streaming connector supports every streaming mode. Therefore, each connector is tagged accordingly. A format tag indicates that the connector requires a certain type of format. + +### File System Connector + +<span class="label label-primary">Source: Batch</span> +<span class="label label-primary">Source: Streaming Append Mode</span> +<span class="label label-primary">Sink: Batch</span> +<span class="label label-primary">Sink: Streaming Append Mode</span> +<span class="label label-info">Format: CSV-only</span> + +The file system connector allows for reading and writing from a local or distributed filesystem. A filesystem can be defined as: + +<div class="codetabs" markdown="1"> +<div data-lang="Java/Scala" markdown="1"> +{% highlight java %} +.connect( + new FileSystem() + .path("file:///path/to/whatever") // required: path to a file or directory +) +{% endhighlight %} +</div> + +<div data-lang="YAML" markdown="1"> +{% highlight yaml %} +connector: + type: filesystem + path: "file:///path/to/whatever" # required: path to a file or directory +{% endhighlight %} +</div> +</div> + +The file system connector itself is included in Flink and does not require an additional dependency. A corresponding format needs to be specified for reading and writing rows from and to a file system. + +<span class="label label-danger">Attention</span> Make sure to include [Flink File System specific dependencies]({{ site.baseurl }}/ops/filesystems.html). + +<span class="label label-danger">Attention</span> File system sources and sinks for streaming are only experimental. In the future, we will support actual streaming use cases, i.e., directory monitoring and bucket output. + +### Kafka Connector + +<span class="label label-primary">Source: Streaming Append Mode</span> +<span class="label label-primary">Sink: Streaming Append Mode</span> +<span class="label label-info">Format: Serialization Schema</span> +<span class="label label-info">Format: Deserialization Schema</span> + +The Kafka connector allows for reading and writing from and to an Apache Kafka topic. It can be defined as follows: + +<div class="codetabs" markdown="1"> +<div data-lang="Java/Scala" markdown="1"> +{% highlight java %} +.connect( + new Kafka() + .version("0.11") // required: valid connector versions are "0.8", "0.9", "0.10", and "0.11" + .topic("...") // required: topic name from which the table is read + + // optional: connector specific properties + .property("zookeeper.connect", "localhost:2181") + .property("bootstrap.servers", "localhost:9092") + .property("group.id", "testGroup") + + // optional: select a startup mode for Kafka offsets + .startFromEarliest() + .startFromLatest() + .startFromSpecificOffsets(...) + + // optional: output partitioning from Flink's partitions into Kafka's partitions + .sinkPartitionerFixed() // each Flink partition ends up in at-most one Kafka partition (default) + .sinkPartitionerRoundRobin() // a Flink partition is distributed to Kafka partitions round-robin + .sinkPartitionerCustom(MyCustom.class) // use a custom FlinkKafkaPartitioner subclass +) +{% endhighlight %} +</div> + +<div data-lang="YAML" markdown="1"> +{% highlight yaml %} +connector: + type: kafka + version: 0.11 # required: valid connector versions are "0.8", "0.9", "0.10", and "0.11" + topic: ... # required: topic name from which the table is read + + properties: # optional: connector specific properties + - key: zookeeper.connect + value: localhost:2181 + - key: bootstrap.servers + value: localhost:9092 + - key: group.id + value: testGroup + + startup-mode: ... # optional: valid modes are "earliest-offset", "latest-offset", + # "group-offsets", or "specific-offsets" + specific-offsets: # optional: used in case of startup mode with specific offsets + - partition: 0 + offset: 42 + - partition: 1 + offset: 300 + + sink-partitioner: ... # optional: output partitioning from Flink's partitions into Kafka's partitions + # valid are "fixed" (each Flink partition ends up in at most one Kafka partition), + # "round-robin" (a Flink partition is distributed to Kafka partitions round-robin) + # "custom" (use a custom FlinkKafkaPartitioner subclass) + sink-partitioner-class: org.mycompany.MyPartitioner # optional: used in case of sink partitioner custom +{% endhighlight %} +</div> +</div> + +**Specify the start reading position:** By default, the Kafka source will start reading data from the committed group offsets in Zookeeper or Kafka brokers. You can specify other start positions, which correspond to the configurations in section [Kafka Consumers Start Position Configuration]({{ site.baseurl }}/dev/connectors/kafka.html#kafka-consumers-start-position-configuration). + +**Flink-Kafka Sink Partitioning:** By default, a Kafka sink writes to at most as many partitions as its own parallelism (each parallel instance of the sink writes to exactly one partition). In order to distribute the writes to more partitions or control the routing of rows into partitions, a custom sink partitioner can be provided. The round-robin partitioner is useful to avoid an unbalanced partitioning. However, it will cause a lot of network connections between all the Flink instances and all the Kafka brokers. + +**Consistency guarantees:** By default, a Kafka sink ingests data with at-least-once guarantees into a Kafka topic if the query is executed with [checkpointing enabled]({{ site.baseurl }}/dev/stream/state/checkpointing.html#enabling-and-configuring-checkpointing). + +**Kafka 0.10+ Timestamps:** Since Kafka 0.10, Kafka messages have a timestamp as metadata that specifies when the record was written into the Kafka topic. These timestamps can be used for a [rowtime attribute](connect.html#defining-the-schema) by selecting `timestamps: from-source` in YAML and `timestampsFromSource()` in Java/Scala respectively. + +Make sure to add the version-specific Kafka dependency. In addition, a corresponding format needs to be specified for reading and writing rows from and to Kafka. + +{% top %} + +Table Formats +------------- + +Flink provides a set of table formats that can be used with table connectors. + +A format tag indicates the format type for matching with a connector. + +### CSV Format + +The CSV format allows to read and write comma-separated rows. + +<div class="codetabs" markdown="1"> +<div data-lang="Java/Scala" markdown="1"> +{% highlight java %} +.withFormat( + new Csv() + .field("field1", Types.STRING) // required: ordered format fields + .field("field2", Types.TIMESTAMP) + .fieldDelimiter(",") // optional: string delimiter "," by default + .lineDelimiter("\n") // optional: string delimiter "\n" by default + .quoteCharacter('"') // optional: single character for string values, empty by default + .commentPrefix('#') // optional: string to indicate comments, empty by default + .ignoreFirstLine() // optional: ignore the first line, by default it is not skipped + .ignoreParseErrors() // optional: skip records with parse error instead of failing by default +) +{% endhighlight %} +</div> + +<div data-lang="YAML" markdown="1"> +{% highlight yaml %} +format: + type: csv + fields: # required: ordered format fields + - name: field1 + type: VARCHAR + - name: field2 + type: TIMESTAMP + field-delimiter: "," # optional: string delimiter "," by default + line-delimiter: "\n" # optional: string delimiter "\n" by default + quote-character: '"' # optional: single character for string values, empty by default + comment-prefix: '#' # optional: string to indicate comments, empty by default + ignore-first-line: false # optional: boolean flag to ignore the first line, by default it is not skipped + ignore-parse-errors: true # optional: skip records with parse error instead of failing by default +{% endhighlight %} +</div> +</div> + +The CSV format is included in Flink and does not require additional dependencies. + +<span class="label label-danger">Attention</span> The CSV format for writing rows is limited at the moment. Only a custom field delimiter is supported as optional parameter. + +### JSON Format + +<span class="label label-info">Format: Serialization Schema</span> +<span class="label label-info">Format: Deserialization Schema</span> + +The JSON format allows to read and write JSON data that corresponds to a given format schema. The format schema can be defined either as a Flink type, as a JSON schema, or derived from the desired table schema. A Flink type enables a more SQL-like definition and mapping to the corresponding SQL data types. The JSON schema allows for more complex and nested structures. + +If the format schema is equal to the table schema, the schema can also be automatically derived. This allows for defining schema information only once. The names, types, and field order of the format are determined by the table's schema. Time attributes are ignored if their origin is not a field. A `from` definition in the table schema is interpreted as a field renaming in the format. + +<div class="codetabs" markdown="1"> +<div data-lang="Java/Scala" markdown="1"> +{% highlight java %} +.withFormat( + new Json() + .failOnMissingField(true) // optional: flag whether to fail if a field is missing or not, false by default + + // required: define the schema either by using type information which parses numbers to corresponding types + .schema(Type.ROW(...)) + + // or by using a JSON schema which parses to DECIMAL and TIMESTAMP + .jsonSchema( + "{" + + " type: 'object'," + + " properties: {" + + " lon: {" + + " type: 'number'" + + " }," + + " rideTime: {" + + " type: 'string'," + + " format: 'date-time'" + + " }" + + " }" + + "}" + ) + + // or use the table's schema + .deriveSchema() +) +{% endhighlight %} +</div> + +<div data-lang="YAML" markdown="1"> +{% highlight yaml %} +format: + type: json + fail-on-missing-field: true # optional: flag whether to fail if a field is missing or not, false by default + + # required: define the schema either by using a type string which parses numbers to corresponding types + schema: "ROW(lon FLOAT, rideTime TIMESTAMP)" + + # or by using a JSON schema which parses to DECIMAL and TIMESTAMP + json-schema: > + { + type: 'object', + properties: { + lon: { + type: 'number' + }, + rideTime: { + type: 'string', + format: 'date-time' + } + } + } + + # or use the table's schema + derive-schema: true +{% endhighlight %} +</div> +</div> + +The following table shows the mapping of JSON schema types to Flink SQL types: + +| JSON schema | Flink SQL | +| :-------------------------------- | :---------------------- | +| `object` | `ROW` | +| `boolean` | `BOOLEAN` | +| `array` | `ARRAY[_]` | +| `number` | `DECIMAL` | +| `integer` | `DECIMAL` | +| `string` | `VARCHAR` | +| `string` with `format: date-time` | `TIMESTAMP` | +| `string` with `format: date` | `DATE` | +| `string` with `format: time` | `TIME` | +| `string` with `encoding: base64` | `ARRAY[TINYINT]` | +| `null` | `NULL` (unsupported yet)| + + +Currently, Flink supports only a subset of the [JSON schema specification](http://json-schema.org/) `draft-07`. Union types (as well as `allOf`, `anyOf`, `not`) are not supported yet. `oneOf` and arrays of types are only supported for specifying nullability. + +Simple references that link to a common definition in the document are supported as shown in the more complex example below: + +{% highlight json %} +{ + "definitions": { + "address": { + "type": "object", + "properties": { + "street_address": { + "type": "string" + }, + "city": { + "type": "string" + }, + "state": { + "type": "string" + } + }, + "required": [ + "street_address", + "city", + "state" + ] + } + }, + "type": "object", + "properties": { + "billing_address": { + "$ref": "#/definitions/address" + }, + "shipping_address": { + "$ref": "#/definitions/address" + }, + "optional_address": { + "oneOf": [ + { + "type": "null" + }, + { + "$ref": "#/definitions/address" + } + ] + } + } +} +{% endhighlight %} + +**Missing Field Handling:** By default, a missing JSON field is set to `null`. You can enable strict JSON parsing that will cancel the source (and query) if a field is missing. + +Make sure to add the JSON format as a dependency. + + +### Apache Avro Format + +<span class="label label-info">Format: Serialization Schema</span> +<span class="label label-info">Format: Deserialization Schema</span> + +The [Apache Avro](https://avro.apache.org/) format allows to read and write Avro data that corresponds to a given format schema. The format schema can be defined either as a fully qualified class name of an Avro specific record or as an Avro schema string. If a class name is used, the class must be available in the classpath during runtime. + +<div class="codetabs" markdown="1"> +<div data-lang="Java/Scala" markdown="1"> +{% highlight java %} +.withFormat( + new Avro() + + // required: define the schema either by using an Avro specific record class + .recordClass(User.class) + + // or by using an Avro schema + .avroSchema( + "{" + + " \"type\": \"record\"," + + " \"name\": \"test\"," + + " \"fields\" : [" + + " {\"name\": \"a\", \"type\": \"long\"}," + + " {\"name\": \"b\", \"type\": \"string\"}" + + " ]" + + "}" + ) +) +{% endhighlight %} +</div> + +<div data-lang="YAML" markdown="1"> +{% highlight yaml %} +format: + type: avro + + # required: define the schema either by using an Avro specific record class + record-class: "org.organization.types.User" + + # or by using an Avro schema + avro-schema: > + { + "type": "record", + "name": "test", + "fields" : [ + {"name": "a", "type": "long"}, + {"name": "b", "type": "string"} + ] + } +{% endhighlight %} +</div> +</div> + +Avro types are mapped to the corresponding SQL data types. Union types are only supported for specifying nullability otherwise they are converted to an `ANY` type. The following table shows the mapping: + +| Avro schema | Flink SQL | +| :------------------------------------------ | :---------------------- | +| `record` | `ROW` | +| `enum` | `VARCHAR` | +| `array` | `ARRAY[_]` | +| `map` | `MAP[VARCHAR, _]` | +| `union` | non-null type or `ANY` | +| `fixed` | `ARRAY[TINYINT]` | +| `string` | `VARCHAR` | +| `bytes` | `ARRAY[TINYINT]` | +| `int` | `INT` | +| `long` | `BIGINT` | +| `float` | `FLOAT` | +| `double` | `DOUBLE` | +| `boolean` | `BOOLEAN` | +| `int` with `logicalType: date` | `DATE` | +| `int` with `logicalType: time-millis` | `TIME` | +| `int` with `logicalType: time-micros` | `INT` | +| `long` with `logicalType: timestamp-millis` | `TIMESTAMP` | +| `long` with `logicalType: timestamp-micros` | `BIGINT` | +| `bytes` with `logicalType: decimal` | `DECIMAL` | +| `fixed` with `logicalType: decimal` | `DECIMAL` | +| `null` | `NULL` (unsupported yet)| + +Avro uses [Joda-Time](http://www.joda.org/joda-time/) for representing logical date and time types in specific record classes. The Joda-Time dependency is not part of Flink's distribution. Therefore, make sure that Joda-Time is in your classpath together with your specific record class during runtime. Avro formats specified via a schema string do not require Joda-Time to be present. + +Make sure to add the Apache Avro dependency. + +{% top %} + +Further TableSources and TableSinks +----------------------------------- + +The following table sources and sinks have not yet been migrated (or have not been migrated entirely) to the new unified interfaces. + +These are the additional `TableSource`s which are provided with Flink: + +| **Class name** | **Maven dependency** | **Batch?** | **Streaming?** | **Description** +| `OrcTableSource` | `flink-orc` | Y | N | A `TableSource` for ORC files. + +These are the additional `TableSink`s which are provided with Flink: + +| **Class name** | **Maven dependency** | **Batch?** | **Streaming?** | **Description** +| `CsvTableSink` | `flink-table` | Y | Append | A simple sink for CSV files. +| `JDBCAppendTableSink` | `flink-jdbc` | Y | Append | Writes a Table to a JDBC table. +| `CassandraAppendTableSink` | `flink-connector-cassandra` | N | Append | Writes a Table to a Cassandra table. + +### OrcTableSource + +The `OrcTableSource` reads [ORC files](https://orc.apache.org). ORC is a file format for structured data and stores the data in a compressed, columnar representation. ORC is very storage efficient and supports projection and filter push-down. + +An `OrcTableSource` is created as shown below: + +<div class="codetabs" markdown="1"> +<div data-lang="java" markdown="1"> +{% highlight java %} + +// create Hadoop Configuration +Configuration config = new Configuration(); + +OrcTableSource orcTableSource = OrcTableSource.builder() + // path to ORC file(s). NOTE: By default, directories are recursively scanned. + .path("file:///path/to/data") + // schema of ORC files + .forOrcSchema("struct<name:string,addresses:array<struct<street:string,zip:smallint>>>") + // Hadoop configuration + .withConfiguration(config) + // build OrcTableSource + .build(); +{% endhighlight %} +</div> + +<div data-lang="scala" markdown="1"> +{% highlight scala %} + +// create Hadoop Configuration +val config = new Configuration() + +val orcTableSource = OrcTableSource.builder() + // path to ORC file(s). NOTE: By default, directories are recursively scanned. + .path("file:///path/to/data") + // schema of ORC files + .forOrcSchema("struct<name:string,addresses:array<struct<street:string,zip:smallint>>>") + // Hadoop configuration + .withConfiguration(config) + // build OrcTableSource + .build() +{% endhighlight %} +</div> +</div> + +**Note:** The `OrcTableSource` does not support ORC's `Union` type yet. + +{% top %} + +### CsvTableSink + +The `CsvTableSink` emits a `Table` to one or more CSV files. + +The sink only supports append-only streaming tables. It cannot be used to emit a `Table` that is continuously updated. See the [documentation on Table to Stream conversions](./streaming.html#table-to-stream-conversion) for details. When emitting a streaming table, rows are written at least once (if checkpointing is enabled) and the `CsvTableSink` does not split output files into bucket files but continuously writes to the same files. + +<div class="codetabs" markdown="1"> +<div data-lang="java" markdown="1"> +{% highlight java %} + +Table table = ... + +table.writeToSink( + new CsvTableSink( + path, // output path + "|", // optional: delimit files by '|' + 1, // optional: write to a single file + WriteMode.OVERWRITE)); // optional: override existing files + +{% endhighlight %} +</div> + +<div data-lang="scala" markdown="1"> +{% highlight scala %} + +val table: Table = ??? + +table.writeToSink( + new CsvTableSink( + path, // output path + fieldDelim = "|", // optional: delimit files by '|' + numFiles = 1, // optional: write to a single file + writeMode = WriteMode.OVERWRITE)) // optional: override existing files + +{% endhighlight %} +</div> +</div> + +### JDBCAppendTableSink + +The `JDBCAppendTableSink` emits a `Table` to a JDBC connection. The sink only supports append-only streaming tables. It cannot be used to emit a `Table` that is continuously updated. See the [documentation on Table to Stream conversions](./streaming.html#table-to-stream-conversion) for details. + +The `JDBCAppendTableSink` inserts each `Table` row at least once into the database table (if checkpointing is enabled). However, you can specify the insertion query using <code>REPLACE</code> or <code>INSERT OVERWRITE</code> to perform upsert writes to the database. + +To use the JDBC sink, you have to add the JDBC connector dependency (<code>flink-jdbc</code>) to your project. Then you can create the sink using <code>JDBCAppendSinkBuilder</code>: + +<div class="codetabs" markdown="1"> +<div data-lang="java" markdown="1"> +{% highlight java %} + +JDBCAppendTableSink sink = JDBCAppendTableSink.builder() + .setDrivername("org.apache.derby.jdbc.EmbeddedDriver") + .setDBUrl("jdbc:derby:memory:ebookshop") + .setQuery("INSERT INTO books (id) VALUES (?)") + .setParameterTypes(INT_TYPE_INFO) + .build(); + +Table table = ... +table.writeToSink(sink); +{% endhighlight %} +</div> + +<div data-lang="scala" markdown="1"> +{% highlight scala %} +val sink: JDBCAppendTableSink = JDBCAppendTableSink.builder() + .setDrivername("org.apache.derby.jdbc.EmbeddedDriver") + .setDBUrl("jdbc:derby:memory:ebookshop") + .setQuery("INSERT INTO books (id) VALUES (?)") + .setParameterTypes(INT_TYPE_INFO) + .build() + +val table: Table = ??? +table.writeToSink(sink) +{% endhighlight %} +</div> +</div> + +Similar to using <code>JDBCOutputFormat</code>, you have to explicitly specify the name of the JDBC driver, the JDBC URL, the query to be executed, and the field types of the JDBC table. + +{% top %} + +### CassandraAppendTableSink + +The `CassandraAppendTableSink` emits a `Table` to a Cassandra table. The sink only supports append-only streaming tables. It cannot be used to emit a `Table` that is continuously updated. See the [documentation on Table to Stream conversions](./streaming.html#table-to-stream-conversion) for details. + +The `CassandraAppendTableSink` inserts all rows at least once into the Cassandra table if checkpointing is enabled. However, you can specify the query as upsert query. + +To use the `CassandraAppendTableSink`, you have to add the Cassandra connector dependency (<code>flink-connector-cassandra</code>) to your project. The example below shows how to use the `CassandraAppendTableSink`. + +<div class="codetabs" markdown="1"> +<div data-lang="java" markdown="1"> +{% highlight java %} + +ClusterBuilder builder = ... // configure Cassandra cluster connection + +CassandraAppendTableSink sink = new CassandraAppendTableSink( + builder, + // the query must match the schema of the table + INSERT INTO flink.myTable (id, name, value) VALUES (?, ?, ?)); + +Table table = ... +table.writeToSink(sink); +{% endhighlight %} +</div> + +<div data-lang="scala" markdown="1"> +{% highlight scala %} +val builder: ClusterBuilder = ... // configure Cassandra cluster connection + +val sink: CassandraAppendTableSink = new CassandraAppendTableSink( + builder, + // the query must match the schema of the table + INSERT INTO flink.myTable (id, name, value) VALUES (?, ?, ?)) + +val table: Table = ??? +table.writeToSink(sink) +{% endhighlight %} +</div> +</div> + +{% top %} \ No newline at end of file diff --git a/docs/dev/table/sourceSinks.md b/docs/dev/table/sourceSinks.md index 3c2152bc7b6..d0cc78e6c56 100644 --- a/docs/dev/table/sourceSinks.md +++ b/docs/dev/table/sourceSinks.md @@ -1,5 +1,5 @@ --- -title: "Table Sources & Sinks" +title: "User-defined Sources & Sinks" nav-parent_id: tableapi nav-pos: 40 --- @@ -22,751 +22,17 @@ specific language governing permissions and limitations under the License. --> -A `TableSource` provides access to data which is stored in external systems (database, key-value store, message queue) or files. After a [TableSource is registered in a TableEnvironment](common.html#register-a-tablesource) it can accessed by [Table API](tableApi.html) or [SQL](sql.html) queries. +A `TableSource` provides access to data which is stored in external systems (database, key-value store, message queue) or files. After a [TableSource is registered in a TableEnvironment](common.html#register-a-tablesource) it can be accessed by [Table API](tableApi.html) or [SQL](sql.html) queries. -A TableSink [emits a Table](common.html#emit-a-table) to an external storage system, such as a database, key-value store, message queue, or file system (in different encodings, e.g., CSV, Parquet, or ORC). +A `TableSink` [emits a Table](common.html#emit-a-table) to an external storage system, such as a database, key-value store, message queue, or file system (in different encodings, e.g., CSV, Parquet, or ORC). -Have a look at the [common concepts and API](common.html) page for details how to [register a TableSource](common.html#register-a-tablesource) and how to [emit a Table through a TableSink](common.html#emit-a-table). +A `TableFactory` allows for separating the declaration of a connection to an external system from the actual implementation. A table factory creates configured instances of table sources and sinks from normalized, string-based properties. The properties can be generated programmatically using a `Descriptor` or via YAML configuration files for the [SQL Client](sqlClient.html). + +Have a look at the [common concepts and API](common.html) page for details how to [register a TableSource](common.html#register-a-tablesource) and how to [emit a Table through a TableSink](common.html#emit-a-table). See the [built-in sources, sinks, and formats](connect.html) page for examples how to use factories. * This will be replaced by the TOC {:toc} -Provided TableSources ---------------------- - -Currently, Flink provides the `CsvTableSource` to read CSV files and a few table sources to read JSON or Avro data from Kafka. -A custom `TableSource` can be defined by implementing the `BatchTableSource` or `StreamTableSource` interface. See section on [defining a custom TableSource](#define-a-tablesource) for details. - -| **Class name** | **Maven dependency** | **Batch?** | **Streaming?** | **Description** -| `Kafka011AvroTableSource` | `flink-connector-kafka-0.11` | N | Y | A `TableSource` for Avro-encoded Kafka 0.11 topics. -| `Kafka011JsonTableSource` | `flink-connector-kafka-0.11` | N | Y | A `TableSource` for flat Json-encoded Kafka 0.11 topics. -| `Kafka010AvroTableSource` | `flink-connector-kafka-0.10` | N | Y | A `TableSource` for Avro-encoded Kafka 0.10 topics. -| `Kafka010JsonTableSource` | `flink-connector-kafka-0.10` | N | Y | A `TableSource` for flat Json-encoded Kafka 0.10 topics. -| `Kafka09AvroTableSource` | `flink-connector-kafka-0.9` | N | Y | A `TableSource` for Avro-encoded Kafka 0.9 topics. -| `Kafka09JsonTableSource` | `flink-connector-kafka-0.9` | N | Y | A `TableSource` for flat Json-encoded Kafka 0.9 topics. -| `Kafka08AvroTableSource` | `flink-connector-kafka-0.8` | N | Y | A `TableSource` for Avro-encoded Kafka 0.8 topics. -| `Kafka08JsonTableSource` | `flink-connector-kafka-0.8` | N | Y | A `TableSource` for flat Json-encoded Kafka 0.8 topics. -| `CsvTableSource` | `flink-table` | Y | Y | A simple `TableSource` for CSV files. -| `OrcTableSource` | `flink-orc` | Y | N | A `TableSource` for ORC files. - -All sources that come with the `flink-table` dependency are directly available for Table API or SQL programs. For all other table sources, you have to add the respective dependency in addition to the `flink-table` dependency. - -{% top %} - -### KafkaJsonTableSource - -A `KafkaJsonTableSource` ingests JSON-encoded messages from a Kafka topic. Currently, only JSON records with flat (non-nested) schema are supported. - -A `KafkaJsonTableSource` is created and configured using a builder. The following example shows how to create a `KafkaJsonTableSource` with basic properties: - -<div class="codetabs" markdown="1"> -<div data-lang="java" markdown="1"> -{% highlight java %} -// create builder -KafkaTableSource source = Kafka010JsonTableSource.builder() - // set Kafka topic - .forTopic("sensors") - // set Kafka consumer properties - .withKafkaProperties(kafkaProps) - // set Table schema - .withSchema(TableSchema.builder() - .field("sensorId", Types.LONG()) - .field("temp", Types.DOUBLE()) - .field("time", Types.SQL_TIMESTAMP()).build()) - .build(); -{% endhighlight %} -</div> - -<div data-lang="scala" markdown="1"> -{% highlight scala %} -// create builder -val source: KafkaTableSource = Kafka010JsonTableSource.builder() - // set Kafka topic - .forTopic("sensors") - // set Kafka consumer properties - .withKafkaProperties(kafkaProps) - // set Table schema - .withSchema(TableSchema.builder() - .field("sensorId", Types.LONG) - .field("temp", Types.DOUBLE) - .field("time", Types.SQL_TIMESTAMP).build()) - .build() -{% endhighlight %} -</div> -</div> - -#### Optional Configuration - -* **Time Attributes:** Please see the sections on [configuring a rowtime attribute](#configure-a-rowtime-attribute) and [configuring a processing time attribute](#configure-a-processing-time-attribute). - -* **Explicit JSON parse schema:** By default, the JSON records are parsed with the table schema. You can configure an explicit JSON schema and provide a mapping from table schema fields to JSON fields as shown in the following example. - -<div class="codetabs" markdown="1"> -<div data-lang="java" markdown="1"> -{% highlight java %} -Map<String, String> mapping = new HashMap<>(); -mapping.put("sensorId", "id"); -mapping.put("temperature", "temp"); - -KafkaTableSource source = Kafka010JsonTableSource.builder() - // ... - // set Table schema - .withSchema(TableSchema.builder() - .field("sensorId", Types.LONG()) - .field("temperature", Types.DOUBLE()).build()) - // set JSON parsing schema - .forJsonSchema(TableSchema.builder() - .field("id", Types.LONG()) - .field("temp", Types.DOUBLE()).build()) - // set mapping from table fields to JSON fields - .withTableToJsonMapping(mapping) - .build(); -{% endhighlight %} -</div> - -<div data-lang="scala" markdown="1"> -{% highlight scala %} -val source: KafkaTableSource = Kafka010JsonTableSource.builder() - // ... - // set Table schema - .withSchema(TableSchema.builder() - .field("sensorId", Types.LONG) - .field("temperature", Types.DOUBLE).build()) - // set JSON parsing schema - .forJsonSchema(TableSchema.builder() - .field("id", Types.LONG) - .field("temp", Types.DOUBLE).build()) - // set mapping from table fields to JSON fields - .withTableToJsonMapping(Map( - "sensorId" -> "id", - "temperature" -> "temp").asJava) - .build() -{% endhighlight %} -</div> -</div> - -* **Missing Field Handling:** By default, a missing JSON field is set to `null`. You can enable strict JSON parsing that will cancel the source (and query) if a field is missing. - -<div class="codetabs" markdown="1"> -<div data-lang="java" markdown="1"> -{% highlight java %} -KafkaTableSource source = Kafka010JsonTableSource.builder() - // ... - // configure missing field behavior - .failOnMissingField(true) - .build(); -{% endhighlight %} -</div> - -<div data-lang="scala" markdown="1"> -{% highlight scala %} -val source: KafkaTableSource = Kafka010JsonTableSource.builder() - // ... - // configure missing field behavior - .failOnMissingField(true) - .build() -{% endhighlight %} -</div> -</div> - -* **Specify the start reading position:** By default, the table source will start reading data from the committed group offsets in Zookeeper or Kafka brokers. You can specify other start positions via the builder's methods, which correspond to the configurations in section [Kafka Consumers Start Position Configuration](../connectors/kafka.html#kafka-consumers-start-position-configuration). - -<div class="codetabs" markdown="1"> -<div data-lang="java" markdown="1"> -{% highlight java %} -KafkaTableSource source = Kafka010JsonTableSource.builder() - // ... - // start reading from the earliest offset - .fromEarliest() - .build(); -{% endhighlight %} -</div> - -<div data-lang="scala" markdown="1"> -{% highlight scala %} -val source: KafkaTableSource = Kafka010JsonTableSource.builder() - // ... - // start reading from the earliest offset - .fromEarliest() - .build() -{% endhighlight %} -</div> -</div> - -{% top %} - -### KafkaAvroTableSource - -A `KafkaAvroTableSource` ingests Avro-encoded records from a Kafka topic. - -A `KafkaAvroTableSource` is created and configured using a builder. The following example shows how to create a `KafkaAvroTableSource` with basic properties: - -<div class="codetabs" markdown="1"> -<div data-lang="java" markdown="1"> -{% highlight java %} -// create builder -KafkaTableSource source = Kafka010AvroTableSource.builder() - // set Kafka topic - .forTopic("sensors") - // set Kafka consumer properties - .withKafkaProperties(kafkaProps) - // set Table schema - .withSchema(TableSchema.builder() - .field("sensorId", Types.LONG()) - .field("temp", Types.DOUBLE()) - .field("time", Types.SQL_TIMESTAMP()).build()) - // set class of Avro record - .forAvroRecordClass(SensorReading.class) - .build(); -{% endhighlight %} -</div> - -<div data-lang="scala" markdown="1"> -{% highlight scala %} -// create builder -val source: KafkaTableSource = Kafka010JsonTableSource.builder() - // set Kafka topic - .forTopic("sensors") - // set Kafka consumer properties - .withKafkaProperties(kafkaProps) - // set Table schema - .withSchema(TableSchema.builder() - .field("sensorId", Types.LONG) - .field("temp", Types.DOUBLE) - .field("time", Types.SQL_TIMESTAMP).build()) - // set class of Avro record - .forAvroRecordClass(classOf[SensorReading]) - .build() -{% endhighlight %} -</div> -</div> - -**NOTE:** The specified Avro record class must provide all fields of the table schema with corresponding type. - -#### Optional Configuration - -* **Time Attributes:** Please see the sections on [configuring a rowtime attribute](#configure-a-rowtime-attribute) and [configuring a processing time attribute](#configure-a-processing-time-attribute). - -* **Explicit Schema Field to Avro Mapping:** By default, all fields of the table schema are mapped by name to fields of the Avro records. If the fields in the Avro records have different names, a mapping from table schema fields to Avro fields can be specified. - -<div class="codetabs" markdown="1"> -<div data-lang="java" markdown="1"> -{% highlight java %} -Map<String, String> mapping = new HashMap<>(); -mapping.put("sensorId", "id"); -mapping.put("temperature", "temp"); - -KafkaTableSource source = Kafka010AvroTableSource.builder() - // ... - // set Table schema - .withSchema(TableSchema.builder() - .field("sensorId", Types.LONG()) - .field("temperature", Types.DOUBLE()).build()) - // set class of Avro record with fields [id, temp] - .forAvroRecordClass(SensorReading.class) - // set mapping from table fields to Avro fields - .withTableToAvroMapping(mapping) - .build(); -{% endhighlight %} -</div> - -<div data-lang="scala" markdown="1"> -{% highlight scala %} -val source: KafkaTableSource = Kafka010AvroTableSource.builder() - // ... - // set Table schema - .withSchema(TableSchema.builder() - .field("sensorId", Types.LONG) - .field("temperature", Types.DOUBLE).build()) - // set class of Avro record with fields [id, temp] - .forAvroRecordClass(classOf[SensorReading]) - // set mapping from table fields to Avro fields - .withTableToAvroMapping(Map( - "sensorId" -> "id", - "temperature" -> "temp").asJava) - .build() -{% endhighlight %} -</div> -</div> - -* **Specify the start reading position:** By default, the table source will start reading data from the committed group offsets in Zookeeper or Kafka brokers. You can specify other start positions via the builder's methods, which correspond to the configurations in section [Kafka Consumers Start Position Configuration](../connectors/kafka.html#kafka-consumers-start-position-configuration). - -<div class="codetabs" markdown="1"> -<div data-lang="java" markdown="1"> -{% highlight java %} -KafkaTableSource source = Kafka010AvroTableSource.builder() - // ... - // start reading from the earliest offset - .fromEarliest() - .build(); -{% endhighlight %} -</div> - -<div data-lang="scala" markdown="1"> -{% highlight scala %} -val source: KafkaTableSource = Kafka010AvroTableSource.builder() - // ... - // start reading from the earliest offset - .fromEarliest() - .build() -{% endhighlight %} -</div> -</div> - -{% top %} - -### Configuring a Processing Time Attribute - -[Processing time attributes](streaming.html#processing-time) are commonly used in streaming queries. A processing time attribute returns the current wall-clock time of the operator that accesses it. - -Batch queries support processing time attributes as well. However, processing time attributes are initialized with the wall-clock time of the table scan operator and keep this value throughout the query evaluation. - -A table schema field of type `SQL_TIMESTAMP` can be declared as a processing time attribute as shown in the following example. - -<div class="codetabs" markdown="1"> -<div data-lang="java" markdown="1"> -{% highlight java %} -KafkaTableSource source = Kafka010JsonTableSource.builder() - // ... - .withSchema(TableSchema.builder() - .field("sensorId", Types.LONG()) - .field("temp", Types.DOUBLE()) - // field "ptime" is of type SQL_TIMESTAMP - .field("ptime", Types.SQL_TIMESTAMP()).build()) - // declare "ptime" as processing time attribute - .withProctimeAttribute("ptime") - .build(); -{% endhighlight %} -</div> - -<div data-lang="scala" markdown="1"> -{% highlight scala %} -val source: KafkaTableSource = Kafka010JsonTableSource.builder() - // ... - .withSchema(TableSchema.builder() - .field("sensorId", Types.LONG) - .field("temp", Types.DOUBLE) - // field "ptime" is of type SQL_TIMESTAMP - .field("ptime", Types.SQL_TIMESTAMP).build()) - // declare "ptime" as processing time attribute - .withProctimeAttribute("ptime") - .build() -{% endhighlight %} -</div> -</div> - -{% top %} - -### Configuring a Rowtime Attribute - -[Rowtime attributes](streaming.html#event-time) are attributes of type `TIMESTAMP` and handled in a unified way in stream and batch queries. - -A table schema field of type `SQL_TIMESTAMP` can be declared as rowtime attribute by specifying - -* the name of the field, -* a `TimestampExtractor` that computes the actual value for the attribute (usually from one or more other attributes), and -* a `WatermarkStrategy` that specifies how watermarks are generated for the the rowtime attribute. - -The following example shows how to configure a rowtime attribute. - -<div class="codetabs" markdown="1"> -<div data-lang="java" markdown="1"> -{% highlight java %} -KafkaTableSource source = Kafka010JsonTableSource.builder() - // ... - .withSchema(TableSchema.builder() - .field("sensorId", Types.LONG()) - .field("temp", Types.DOUBLE()) - // field "rtime" is of type SQL_TIMESTAMP - .field("rtime", Types.SQL_TIMESTAMP()).build()) - .withRowtimeAttribute( - // "rtime" is rowtime attribute - "rtime", - // value of "rtime" is extracted from existing field with same name - new ExistingField("rtime"), - // values of "rtime" are at most out-of-order by 30 seconds - new BoundedOutOfOrderWatermarks(30000L)) - .build(); -{% endhighlight %} -</div> - -<div data-lang="scala" markdown="1"> -{% highlight scala %} -val source: KafkaTableSource = Kafka010JsonTableSource.builder() - // ... - .withSchema(TableSchema.builder() - .field("sensorId", Types.LONG) - .field("temp", Types.DOUBLE) - // field "rtime" is of type SQL_TIMESTAMP - .field("rtime", Types.SQL_TIMESTAMP).build()) - .withRowtimeAttribute( - // "rtime" is rowtime attribute - "rtime", - // value of "rtime" is extracted from existing field with same name - new ExistingField("rtime"), - // values of "rtime" are at most out-of-order by 30 seconds - new BoundedOutOfOrderTimestamps(30000L)) - .build() -{% endhighlight %} -</div> -</div> - -#### Extracting Kafka 0.10+ Timestamps into Rowtime Attribute - -Since Kafka 0.10, Kafka messages have a timestamp as metadata that specifies when the record was written into the Kafka topic. `KafkaTableSources` can assign Kafka's message timestamp as rowtime attribute as follows: - -<div class="codetabs" markdown="1"> -<div data-lang="java" markdown="1"> -{% highlight java %} -KafkaTableSource source = Kafka010JsonTableSource.builder() - // ... - .withSchema(TableSchema.builder() - .field("sensorId", Types.LONG()) - .field("temp", Types.DOUBLE()) - // field "rtime" is of type SQL_TIMESTAMP - .field("rtime", Types.SQL_TIMESTAMP()).build()) - // use Kafka timestamp as rowtime attribute - .withKafkaTimestampAsRowtimeAttribute()( - // "rtime" is rowtime attribute - "rtime", - // values of "rtime" are ascending - new AscendingTimestamps()) - .build(); -{% endhighlight %} -</div> - -<div data-lang="scala" markdown="1"> -{% highlight scala %} -val source: KafkaTableSource = Kafka010JsonTableSource.builder() - // ... - .withSchema(TableSchema.builder() - .field("sensorId", Types.LONG) - .field("temp", Types.DOUBLE) - // field "rtime" is of type SQL_TIMESTAMP - .field("rtime", Types.SQL_TIMESTAMP).build()) - // use Kafka timestamp as rowtime attribute - .withKafkaTimestampAsRowtimeAttribute()( - // "rtime" is rowtime attribute - "rtime", - // values of "rtime" are ascending - new AscendingTimestamps()) - .build() -{% endhighlight %} -</div> -</div> - -#### Provided TimestampExtractors - -Flink provides `TimestampExtractor` implementations for common use cases. -The following `TimestampExtractor` implementations are currently available: - -* `ExistingField(fieldName)`: Extracts the value of a rowtime attribute from an existing `LONG`, `SQL_TIMESTAMP`, or timestamp formatted `STRING` field. One example of such a string would be '2018-05-28 12:34:56.000'. -* `StreamRecordTimestamp()`: Extracts the value of a rowtime attribute from the timestamp of the `DataStream` `StreamRecord`. Note, this `TimestampExtractor` is not available for batch table sources. - -A custom `TimestampExtractor` can be defined by implementing the corresponding interface. - -#### Provided WatermarkStrategies - -Flink provides `WatermarkStrategy` implementations for common use cases. -The following `WatermarkStrategy` implementations are currently available: - -* `AscendingTimestamps`: A watermark strategy for ascending timestamps. Records with timestamps that are out-of-order will be considered late. -* `BoundedOutOfOrderTimestamps(delay)`: A watermark strategy for timestamps that are at most out-of-order by the specified delay. - -A custom `WatermarkStrategy` can be defined by implementing the corresponding interface. - -{% top %} - -### CsvTableSource - -The `CsvTableSource` is already included in `flink-table` without additional dependencies. - -The easiest way to create a `CsvTableSource` is by using the enclosed builder `CsvTableSource.builder()`, the builder has the following methods to configure properties: - - - `path(String path)` Sets the path to the CSV file, required. - - `field(String fieldName, TypeInformation<?> fieldType)` Adds a field with the field name and field type information, can be called multiple times, required. The call order of this method defines also the order of the fields in a row. - - `fieldDelimiter(String delim)` Sets the field delimiter, `","` by default. - - `lineDelimiter(String delim)` Sets the line delimiter, `"\n"` by default. - - `quoteCharacter(Character quote)` Sets the quote character for String values, `null` by default. - - `commentPrefix(String prefix)` Sets a prefix to indicate comments, `null` by default. - - `ignoreFirstLine()` Ignore the first line. Disabled by default. - - `ignoreParseErrors()` Skip records with parse error instead to fail. Throwing an exception by default. - -You can create the source as follows: - -<div class="codetabs" markdown="1"> -<div data-lang="java" markdown="1"> -{% highlight java %} -CsvTableSource csvTableSource = CsvTableSource - .builder() - .path("/path/to/your/file.csv") - .field("name", Types.STRING()) - .field("id", Types.INT()) - .field("score", Types.DOUBLE()) - .field("comments", Types.STRING()) - .fieldDelimiter("#") - .lineDelimiter("$") - .ignoreFirstLine() - .ignoreParseErrors() - .commentPrefix("%") - .build(); -{% endhighlight %} -</div> - -<div data-lang="scala" markdown="1"> -{% highlight scala %} -val csvTableSource = CsvTableSource - .builder - .path("/path/to/your/file.csv") - .field("name", Types.STRING) - .field("id", Types.INT) - .field("score", Types.DOUBLE) - .field("comments", Types.STRING) - .fieldDelimiter("#") - .lineDelimiter("$") - .ignoreFirstLine - .ignoreParseErrors - .commentPrefix("%") - .build -{% endhighlight %} -</div> -</div> - -{% top %} - -### OrcTableSource - -The `OrcTableSource` reads [ORC files](https://orc.apache.org). ORC is a file format for structured data and stores the data in a compressed, columnar representation. ORC is very storage efficient and supports projection and filter push-down. - -An `OrcTableSource` is created as shown below: - -<div class="codetabs" markdown="1"> -<div data-lang="java" markdown="1"> -{% highlight java %} - -// create Hadoop Configuration -Configuration config = new Configuration(); - -OrcTableSource orcTableSource = OrcTableSource.builder() - // path to ORC file(s). NOTE: By default, directories are recursively scanned. - .path("file:///path/to/data") - // schema of ORC files - .forOrcSchema("struct<name:string,addresses:array<struct<street:string,zip:smallint>>>") - // Hadoop configuration - .withConfiguration(config) - // build OrcTableSource - .build(); -{% endhighlight %} -</div> - -<div data-lang="scala" markdown="1"> -{% highlight scala %} - -// create Hadoop Configuration -val config = new Configuration() - -val orcTableSource = OrcTableSource.builder() - // path to ORC file(s). NOTE: By default, directories are recursively scanned. - .path("file:///path/to/data") - // schema of ORC files - .forOrcSchema("struct<name:string,addresses:array<struct<street:string,zip:smallint>>>") - // Hadoop configuration - .withConfiguration(config) - // build OrcTableSource - .build() -{% endhighlight %} -</div> -</div> - -**Note:** The `OrcTableSource` does not support ORC's `Union` type yet. - -{% top %} - -Provided TableSinks -------------------- - -The following table lists the `TableSink`s which are provided with Flink. - -| **Class name** | **Maven dependency** | **Batch?** | **Streaming?** | **Description** -| `CsvTableSink` | `flink-table` | Y | Append | A simple sink for CSV files. -| `JDBCAppendTableSink` | `flink-jdbc` | Y | Append | Writes a Table to a JDBC table. -| `CassandraAppendTableSink` | `flink-connector-cassandra` | N | Append | Writes a Table to a Cassandra table. -| `Kafka08JsonTableSink` | `flink-connector-kafka-0.8` | N | Append | A Kafka 0.8 sink with JSON encoding. -| `Kafka09JsonTableSink` | `flink-connector-kafka-0.9` | N | Append | A Kafka 0.9 sink with JSON encoding. -| `Kafka010JsonTableSink` | `flink-connector-kafka-0.10` | N | Append | A Kafka 0.10 sink with JSON encoding. - -All sinks that come with the `flink-table` dependency can be directly used by your Table programs. For all other table sinks, you have to add the respective dependency in addition to the `flink-table` dependency. - -A custom `TableSink` can be defined by implementing the `BatchTableSink`, `AppendStreamTableSink`, `RetractStreamTableSink`, or `UpsertStreamTableSink` interface. See section on [defining a custom TableSink](#define-a-tablesink) for details. - -{% top %} - -### KafkaJsonTableSink - -A `KafkaJsonTableSink` emits a [streaming append `Table`](./streaming.html#table-to-stream-conversion) to an Apache Kafka topic. The rows of the table are encoded as JSON records. Currently, only tables with flat schema, i.e., non-nested fields, are supported. - -A `KafkaJsonTableSink` produces with at-least-once guarantees into a Kafka topic if the query is executed with [checkpointing enabled]({{ site.baseurl }}/dev/stream/state/checkpointing.html#enabling-and-configuring-checkpointing). - -By default, a `KafkaJsonTableSink` writes to at most as many partitions as its own parallelism (each parallel instance of the sink writes to exactly one partition). In order to distribute the writes to more partitions or control the routing of rows into partitions, a custom `FlinkKafkaPartitioner` can be provided. - -The following example shows how to create a `KafkaJsonTableSink` for Kafka 0.10. Sinks for Kafka 0.8 and 0.9 are instantiated analogously. - -<div class="codetabs" markdown="1"> -<div data-lang="java" markdown="1"> -{% highlight java %} - -Table table = ... - -Properties props = new Properties(); -props.setProperty("bootstrap.servers", "localhost:9092"); - -table.writeToSink( - new Kafka010JsonTableSink( - "myTopic", // Kafka topic to write to - props)); // Properties to configure the producer - -{% endhighlight %} -</div> - -<div data-lang="scala" markdown="1"> -{% highlight scala %} - -val table: Table = ??? - -val props = new Properties() -props.setProperty("bootstrap.servers", "localhost:9092") - -table.writeToSink( - new Kafka010JsonTableSink( - "myTopic", // Kafka topic to write to - props)) // Properties to configure the producer - -{% endhighlight %} -</div> -</div> - -### CsvTableSink - -The `CsvTableSink` emits a `Table` to one or more CSV files. - -The sink only supports append-only streaming tables. It cannot be used to emit a `Table` that is continuously updated. See the [documentation on Table to Stream conversions](./streaming.html#table-to-stream-conversion) for details. When emitting a streaming table, rows are written at least once (if checkpointing is enabled) and the `CsvTableSink` does not split output files into bucket files but continuously writes to the same files. - -<div class="codetabs" markdown="1"> -<div data-lang="java" markdown="1"> -{% highlight java %} - -Table table = ... - -table.writeToSink( - new CsvTableSink( - path, // output path - "|", // optional: delimit files by '|' - 1, // optional: write to a single file - WriteMode.OVERWRITE)); // optional: override existing files - -{% endhighlight %} -</div> - -<div data-lang="scala" markdown="1"> -{% highlight scala %} - -val table: Table = ??? - -table.writeToSink( - new CsvTableSink( - path, // output path - fieldDelim = "|", // optional: delimit files by '|' - numFiles = 1, // optional: write to a single file - writeMode = WriteMode.OVERWRITE)) // optional: override existing files - -{% endhighlight %} -</div> -</div> - -### JDBCAppendTableSink - -The `JDBCAppendTableSink` emits a `Table` to a JDBC connection. The sink only supports append-only streaming tables. It cannot be used to emit a `Table` that is continuously updated. See the [documentation on Table to Stream conversions](./streaming.html#table-to-stream-conversion) for details. - -The `JDBCAppendTableSink` inserts each `Table` row at least once into the database table (if checkpointing is enabled). However, you can specify the insertion query using <code>REPLACE</code> or <code>INSERT OVERWRITE</code> to perform upsert writes to the database. - -To use the JDBC sink, you have to add the JDBC connector dependency (<code>flink-jdbc</code>) to your project. Then you can create the sink using <code>JDBCAppendSinkBuilder</code>: - -<div class="codetabs" markdown="1"> -<div data-lang="java" markdown="1"> -{% highlight java %} - -JDBCAppendTableSink sink = JDBCAppendTableSink.builder() - .setDrivername("org.apache.derby.jdbc.EmbeddedDriver") - .setDBUrl("jdbc:derby:memory:ebookshop") - .setQuery("INSERT INTO books (id) VALUES (?)") - .setParameterTypes(INT_TYPE_INFO) - .build(); - -Table table = ... -table.writeToSink(sink); -{% endhighlight %} -</div> - -<div data-lang="scala" markdown="1"> -{% highlight scala %} -val sink: JDBCAppendTableSink = JDBCAppendTableSink.builder() - .setDrivername("org.apache.derby.jdbc.EmbeddedDriver") - .setDBUrl("jdbc:derby:memory:ebookshop") - .setQuery("INSERT INTO books (id) VALUES (?)") - .setParameterTypes(INT_TYPE_INFO) - .build() - -val table: Table = ??? -table.writeToSink(sink) -{% endhighlight %} -</div> -</div> - -Similar to using <code>JDBCOutputFormat</code>, you have to explicitly specify the name of the JDBC driver, the JDBC URL, the query to be executed, and the field types of the JDBC table. - -{% top %} - -### CassandraAppendTableSink - -The `CassandraAppendTableSink` emits a `Table` to a Cassandra table. The sink only supports append-only streaming tables. It cannot be used to emit a `Table` that is continuously updated. See the [documentation on Table to Stream conversions](./streaming.html#table-to-stream-conversion) for details. - -The `CassandraAppendTableSink` inserts all rows at least once into the Cassandra table if checkpointing is enabled. However, you can specify the query as upsert query. - -To use the `CassandraAppendTableSink`, you have to add the Cassandra connector dependency (<code>flink-connector-cassandra</code>) to your project. The example below shows how to use the `CassandraAppendTableSink`. - -<div class="codetabs" markdown="1"> -<div data-lang="java" markdown="1"> -{% highlight java %} - -ClusterBuilder builder = ... // configure Cassandra cluster connection - -CassandraAppendTableSink sink = new CassandraAppendTableSink( - builder, - // the query must match the schema of the table - INSERT INTO flink.myTable (id, name, value) VALUES (?, ?, ?)); - -Table table = ... -table.writeToSink(sink); -{% endhighlight %} -</div> - -<div data-lang="scala" markdown="1"> -{% highlight scala %} -val builder: ClusterBuilder = ... // configure Cassandra cluster connection - -val sink: CassandraAppendTableSink = new CassandraAppendTableSink( - builder, - // the query must match the schema of the table - INSERT INTO flink.myTable (id, name, value) VALUES (?, ?, ?)) - -val table: Table = ??? -table.writeToSink(sink) -{% endhighlight %} -</div> -</div> - -{% top %} - Define a TableSource -------------------- @@ -869,6 +135,8 @@ StreamTableSource[T] extends TableSource[T] { * `getDataStream(execEnv)`: Returns a `DataStream` with the data of the table. The type of the `DataStream` must be identical to the return type defined by the `TableSource.getReturnType()` method. The `DataStream` can by created using a regular [data source]({{ site.baseurl }}/dev/datastream_api.html#data-sources) of the DataStream API. Commonly, a `StreamTableSource` is implemented by wrapping a `SourceFunction` or a [stream connector]({{ site.baseurl }}/dev/connectors/). +{% top %} + ### Defining a TableSource with Time Attributes Time-based operations of streaming [Table API](tableApi.html#group-windows) and [SQL](sql.html#group-windows) queries, such as windowed aggregations or joins, require explicitly specified [time attributes]({{ site.baseurl }}/dev/table/streaming.html#time-attributes). @@ -877,7 +145,7 @@ A `TableSource` defines a time attribute as a field of type `Types.SQL_TIMESTAMP #### Defining a Processing Time Attribute -A `TableSource` defines a [processing time attribute](streaming.html#processing-time) by implementing the `DefinedProctimeAttribute` interface. The interface looks as follows: +[Processing time attributes](streaming.html#processing-time) are commonly used in streaming queries. A processing time attribute returns the current wall-clock time of the operator that accesses it. A `TableSource` defines a processing time attribute by implementing the `DefinedProctimeAttribute` interface. The interface looks as follows: <div class="codetabs" markdown="1"> <div data-lang="java" markdown="1"> @@ -901,11 +169,19 @@ DefinedProctimeAttribute { * `getProctimeAttribute()`: Returns the name of the processing time attribute. The specified attribute must be defined of type `Types.SQL_TIMESTAMP` in the table schema and can be used in time-based operations. A `DefinedProctimeAttribute` table source can define no processing time attribute by returning `null`. -**Note** Both `StreamTableSource` and `BatchTableSource` can implement `DefinedProctimeAttribute` and define a processing time attribute. In case of a `BatchTableSource` the processing time field is initialized with the current timestamp during the table scan. +<span class="label label-danger">Attention</span> Both `StreamTableSource` and `BatchTableSource` can implement `DefinedProctimeAttribute` and define a processing time attribute. In case of a `BatchTableSource` the processing time field is initialized with the current timestamp during the table scan. #### Defining a Rowtime Attribute -A `TableSource` defines a [rowtime attribute](streaming.html#event-time) by implementing the `DefinedRowtimeAttributes` interface. The interface looks as follows: +[Rowtime attributes](streaming.html#event-time) are attributes of type `TIMESTAMP` and handled in a unified way in stream and batch queries. + +A table schema field of type `SQL_TIMESTAMP` can be declared as rowtime attribute by specifying + +* the name of the field, +* a `TimestampExtractor` that computes the actual value for the attribute (usually from one or more other fields), and +* a `WatermarkStrategy` that specifies how watermarks are generated for the the rowtime attribute. + +A `TableSource` defines a rowtime attribute by implementing the `DefinedRowtimeAttributes` interface. The interface looks as follows: <div class="codetabs" markdown="1"> <div data-lang="java" markdown="1"> @@ -931,9 +207,33 @@ DefinedRowtimeAttributes { * `attributeName`: The name of the rowtime attribute in the table schema. The field must be defined with type `Types.SQL_TIMESTAMP`. * `timestampExtractor`: The timestamp extractor extracts the timestamp from a record with the return type. For example, it can convert convert a Long field into a timestamp or parse a String-encoded timestamp. Flink comes with a set of built-in `TimestampExtractor` implementation for common use cases. It is also possible to provide a custom implementation. * `watermarkStrategy`: The watermark strategy defines how watermarks are generated for the rowtime attribute. Flink comes with a set of built-in `WatermarkStrategy` implementations for common use cases. It is also possible to provide a custom implementation. -* **Note** Although the `getRowtimeAttributeDescriptors()` method returns a list of descriptors, only a single rowtime attribute is support at the moment. We plan to remove this restriction in the future and support tables with more than one rowtime attribute. -**IMPORTANT** Both, `StreamTableSource` and `BatchTableSource`, can implement `DefinedRowtimeAttributes` and define a rowtime attribute. In either case, the rowtime field is extracted using the `TimestampExtractor`. Hence, a `TableSource` that implements `StreamTableSource` and `BatchTableSource` and defines a rowtime attribute provides exactly the same data to streaming and batch queries. +<span class="label label-danger">Attention</span> Although the `getRowtimeAttributeDescriptors()` method returns a list of descriptors, only a single rowtime attribute is support at the moment. We plan to remove this restriction in the future and support tables with more than one rowtime attribute. + +<span class="label label-danger">Attention</span> Both, `StreamTableSource` and `BatchTableSource`, can implement `DefinedRowtimeAttributes` and define a rowtime attribute. In either case, the rowtime field is extracted using the `TimestampExtractor`. Hence, a `TableSource` that implements `StreamTableSource` and `BatchTableSource` and defines a rowtime attribute provides exactly the same data to streaming and batch queries. + +##### Provided Timestamp Extractors + +Flink provides `TimestampExtractor` implementations for common use cases. + +The following `TimestampExtractor` implementations are currently available: + +* `ExistingField(fieldName)`: Extracts the value of a rowtime attribute from an existing `LONG`, `SQL_TIMESTAMP`, or timestamp formatted `STRING` field. One example of such a string would be '2018-05-28 12:34:56.000'. +* `StreamRecordTimestamp()`: Extracts the value of a rowtime attribute from the timestamp of the `DataStream` `StreamRecord`. Note, this `TimestampExtractor` is not available for batch table sources. + +A custom `TimestampExtractor` can be defined by implementing the corresponding interface. + +##### Provided Watermark Strategies + +Flink provides `WatermarkStrategy` implementations for common use cases. + +The following `WatermarkStrategy` implementations are currently available: + +* `AscendingTimestamps`: A watermark strategy for ascending timestamps. Records with timestamps that are out-of-order will be considered late. +* `BoundedOutOfOrderTimestamps(delay)`: A watermark strategy for timestamps that are at most out-of-order by the specified delay. +* `PreserveWatermarks()`: A strategy which indicates the watermarks should be preserved from the underlying `DataStream`. + +A custom `WatermarkStrategy` can be defined by implementing the corresponding interface. {% top %} @@ -1203,3 +503,239 @@ A message with true boolean field is an upsert message for the configured key. A {% top %} +Define a TableFactory +--------------------- + +A `TableFactory` allows to create different table-related instances from string-based properties. All available factories are called for matching to the given set of properties and a corresponding factory class. + +Factories leverage Java's [Service Provider Interfaces (SPI)](https://docs.oracle.com/javase/tutorial/sound/SPI-intro.html) for discovering. This means that every dependency and JAR file should contain a file `org.apache.flink.table.factories.TableFactory` in the `META_INF/services` resource directory that lists all available table factories that it provides. + +Every table factory needs to implement the following interface: + +<div class="codetabs" markdown="1"> +<div data-lang="java" markdown="1"> +{% highlight java %} +package org.apache.flink.table.factories; + +interface TableFactory { + + Map<String, String> requiredContext(); + + List<String> supportedProperties(); +} +{% endhighlight %} +</div> + +<div data-lang="scala" markdown="1"> +{% highlight scala %} +package org.apache.flink.table.factories + +trait TableFactory { + + def requiredContext(): util.Map[String, String] + + def supportedProperties(): util.List[String] +} +{% endhighlight %} +</div> +</div> + +* `requiredContext()`: Specifies the context that this factory has been implemented for. The framework guarantees to only match for this factory if the specified set of properties and values are met. Typical properties might be `connector.type`, `format.type`, or `update-mode`. Property keys such as `connector.property-version` and `format.property-version` are reserved for future backwards compatibility cases. +* `supportedProperties`: List of property keys that this factory can handle. This method will be used for validation. If a property is passed that this factory cannot handle, an exception will be thrown. The list must not contain the keys that are specified by the context. + +In order to create a specific instance, a factory class can implement one or more interfaces provided in `org.apache.flink.table.factories`: + +* `BatchTableSourceFactory`: Creates a batch table source. +* `BatchTableSinkFactory`: Creates a batch table sink. +* `StreamTableSoureFactory`: Creates a stream table source. +* `StreamTableSinkFactory`: Creates a stream table sink. +* `DeserializationSchemaFactory`: Creates a deserialization schema format. +* `SerializationSchemaFactory`: Creates a serialization schema format. + +The discovery of a factory happens in multiple stages: + +- Discover all available factories. +- Filter by factory class (e.g., `StreamTableSourceFactory`). +- Filter by matching context. +- Filter by supported properties. +- Verify that exactly one factory matches, otherwise throw an `AmbiguousTableFactoryException` or `NoMatchingTableFactoryException`. + +The following example shows how to provide a custom streaming source with an additional `connector.debug` property flag for parameterization. + +<div class="codetabs" markdown="1"> +<div data-lang="java" markdown="1"> +{% highlight java %} +import org.apache.flink.table.sources.StreamTableSource; +import org.apache.flink.types.Row; +import java.util.ArrayList; +import java.util.HashMap; +import java.util.List; +import java.util.Map; + +class MySystemTableSourceFactory extends StreamTableSourceFactory<Row> { + + @Override + public Map<String, String> requiredContext() { + Map<String, String> context = new HashMap<>(); + context.put("update-mode", "append"); + context.put("connector.type", "my-system"); + return context; + } + + @Override + public List<String> supportedProperties() { + List<String> list = new ArrayList<>(); + list.add("connector.debug"); + return list; + } + + @Override + public StreamTableSource<Row> createStreamTableSource(Map<String, String> properties) { + boolean isDebug = Boolean.valueOf(properties.get("connector.debug")); + + # additional validation of the passed properties can also happen here + + return new MySystemAppendTableSource(isDebug); + } +} +{% endhighlight %} +</div> + +<div data-lang="scala" markdown="1"> +{% highlight scala %} +import java.util +import org.apache.flink.table.sources.StreamTableSource +import org.apache.flink.types.Row + +class MySystemTableSourceFactory extends StreamTableSourceFactory[Row] { + + override def requiredContext(): util.Map[String, String] = { + val context = new util.HashMap[String, String]() + context.put("update-mode", "append") + context.put("connector.type", "my-system") + context + } + + override def supportedProperties(): util.List[String] = { + val properties = new util.ArrayList[String]() + properties.add("connector.debug") + properties + } + + override def createStreamTableSource(properties: util.Map[String, String]): StreamTableSource[Row] = { + val isDebug = java.lang.Boolean.valueOf(properties.get("connector.debug")) + + # additional validation of the passed properties can also happen here + + new MySystemAppendTableSource(isDebug) + } +} +{% endhighlight %} +</div> +</div> + +{% top %} + +### Use a TableFactory in the SQL Client + +In a SQL Client environment file, the previously presented factory could be declared as: + +{% highlight yaml %} +tables: + - name: MySystemTable + type: source + update-mode: append + connector: + type: my-system + debug: true +{% endhighlight %} + +The YAML file is translated into flattened string properties and a table factory is called with those properties that describe the connection to the external system: + +{% highlight text %} +update-mode=append +connector.type=my-system +connector.debug=true +{% endhighlight %} + +<span class="label label-danger">Attention</span> Properties such as `tables.#.name` or `tables.#.type` are SQL Client specifics and are not passed to any factory. The `type` property decides, depending on the execution environment, whether a `BatchTableSourceFactory`/`StreamTableSourceFactory` (for `source`), a `BatchTableSinkFactory`/`StreamTableSinkFactory` (for `sink`), or both (for `both`) need to discovered. + +{% top %} + +### Use a TableFactory in the Table & SQL API + +For a type-safe, programmatic approach with explanatory Scaladoc/Javadoc, the Table & SQL API offers descriptors in `org.apache.flink.table.descriptors` that translate into string-based properties. See the [built-in descriptors](connect.md) for sources, sinks, and formats as a reference. + +A connector for `MySystem` in our example can extend `ConnectorDescriptor` as shown below: + +<div class="codetabs" markdown="1"> +<div data-lang="java" markdown="1"> +{% highlight java %} +import org.apache.flink.table.descriptors.ConnectorDescriptor; +import org.apache.flink.table.descriptors.DescriptorProperties; + +/** + * Connector to MySystem with debug mode. + */ +public class MySystemConnector extends ConnectorDescriptor { + + public final boolean isDebug; + + public MySystemConnector(boolean isDebug) { + super("my-system", 1, false); + this.isDebug = isDebug; + } + + @Override + public void addConnectorProperties(DescriptorProperties properties) { + properties.putString("connector.debug", Boolean.toString(isDebug)); + } +} +{% endhighlight %} +</div> + +<div data-lang="scala" markdown="1"> +{% highlight scala %} +import org.apache.flink.table.descriptors.ConnectorDescriptor +import org.apache.flink.table.descriptors.DescriptorProperties + +/** + * Connector to MySystem with debug mode. + */ +class MySystemConnector(isDebug: Boolean) extends ConnectorDescriptor("my-system", 1, formatNeeded = false) { + + override protected def addConnectorProperties(properties: DescriptorProperties): Unit = { + properties.putString("connector.debug", isDebug.toString) + } +} +{% endhighlight %} +</div> +</div> + +The descriptor can then be used in the API as follows: + +<div class="codetabs" markdown="1"> +<div data-lang="java" markdown="1"> +{% highlight java %} +StreamTableEnvironment tableEnv = // ... + +tableEnv + .connect(new MySystemConnector(true)) + .inAppendMode() + .registerTableSource("MySystemTable"); +{% endhighlight %} +</div> + +<div data-lang="scala" markdown="1"> +{% highlight scala %} +val tableEnv: StreamTableEnvironment = // ... + +tableEnv + .connect(new MySystemConnector(isDebug = true)) + .inAppendMode() + .registerTableSource("MySystemTable") +{% endhighlight %} +</div> +</div> + +{% top %} diff --git a/docs/dev/table/sqlClient.md b/docs/dev/table/sqlClient.md index 24af6557dc6..d2d5cde6453 100644 --- a/docs/dev/table/sqlClient.md +++ b/docs/dev/table/sqlClient.md @@ -163,11 +163,6 @@ Every environment file is a regular [YAML file](http://yaml.org/). An example of tables: - name: MyTableName type: source - schema: - - name: MyField1 - type: INT - - name: MyField2 - type: VARCHAR connector: type: filesystem path: "/path/to/something.csv" @@ -180,6 +175,11 @@ tables: type: VARCHAR line-delimiter: "\n" comment-prefix: "#" + schema: + - name: MyField1 + type: INT + - name: MyField2 + type: VARCHAR # Execution properties allow for changing the behavior of a table program. @@ -222,50 +222,32 @@ Queries that are executed in a batch environment, can only be retrieved using th The SQL Client does not require to setup a Java project using Maven or SBT. Instead, you can pass the dependencies as regular JAR files that get submitted to the cluster. You can either specify each JAR file separately (using `--jar`) or define entire library directories (using `--library`). For connectors to external systems (such as Apache Kafka) and corresponding data formats (such as JSON), Flink provides **ready-to-use JAR bundles**. These JAR files are suffixed with `sql-jar` and can be downloaded for each release from the Maven central repository. -{% if site.is_stable %} - -#### Connectors - -| Name | Version | Download | -| :---------------- | :------------ | :--------------------- | -| Filesystem | | Built-in | -| Apache Kafka | 0.9 | [Download](http://central.maven.org/maven2/org/apache/flink/flink-connector-kafka-0.9{{site.scala_version_suffix}}/{{site.version}}/flink-connector-kafka-0.9{{site.scala_version_suffix}}-{{site.version}}-sql-jar.jar) | -| Apache Kafka | 0.10 | [Download](http://central.maven.org/maven2/org/apache/flink/flink-connector-kafka-0.10{{site.scala_version_suffix}}/{{site.version}}/flink-connector-kafka-0.10{{site.scala_version_suffix}}-{{site.version}}-sql-jar.jar) | -| Apache Kafka | 0.11 | [Download](http://central.maven.org/maven2/org/apache/flink/flink-connector-kafka-0.11{{site.scala_version_suffix}}/{{site.version}}/flink-connector-kafka-0.11{{site.scala_version_suffix}}-{{site.version}}-sql-jar.jar) | - -#### Formats - -| Name | Download | -| :---------------- | :--------------------- | -| CSV | Built-in | -| JSON | [Download](http://central.maven.org/maven2/org/apache/flink/flink-json/{{site.version}}/flink-json-{{site.version}}-sql-jar.jar) | -| Apache Avro | [Download](http://central.maven.org/maven2/org/apache/flink/flink-avro/{{site.version}}/flink-avro-{{site.version}}-sql-jar.jar) | - -{% endif %} - -{% top %} - -Table Sources -------------- - -Sources are defined using a set of [YAML properties](http://yaml.org/). Similar to a SQL `CREATE TABLE` statement you define the name of the table, the final schema of the table, connector, and a data format if necessary. Additionally, you have to specify its type (source, sink, or both). - -{% highlight yaml %} -name: MyTable # required: string representing the table name -type: source # required: currently only 'source' is supported -schema: ... # required: final table schema -connector: ... # required: connector configuration -format: ... # optional: format that depends on the connector -{% endhighlight %} - -<span class="label label-danger">Attention</span> Not every combination of connector and format is supported. Internally, your YAML file is translated into a set of string-based properties by which the SQL Client tries to resolve a matching table source. If a table source can be resolved also depends on the JAR files available in the classpath. +The full list of offered SQL JARs and documentation about how to use them can be found on the [connection to external systems page](connect.html). -The following example shows an environment file that defines a table source reading JSON data from Apache Kafka. All properties are explained in the following subsections. +The following example shows an environment file that defines a table source reading JSON data from Apache Kafka. {% highlight yaml %} tables: - name: TaxiRides type: source + update-mode: append + connector: + property-version: 1 + type: kafka + version: 0.11 + topic: TaxiRides + startup-mode: earliest-offset + properties: + - key: zookeeper.connect + value: localhost:2181 + - key: bootstrap.servers + value: localhost:9092 + - key: group.id + value: testGroup + format: + property-version: 1 + type: json + schema: "ROW(rideId LONG, lon FLOAT, lat FLOAT, rideTime TIMESTAMP)" schema: - name: rideId type: LONG @@ -285,351 +267,11 @@ tables: - name: procTime type: TIMESTAMP proctime: true - connector: - property-version: 1 - type: kafka - version: 0.11 - topic: TaxiRides - startup-mode: earliest-offset - properties: - - key: zookeeper.connect - value: localhost:2181 - - key: bootstrap.servers - value: localhost:9092 - - key: group.id - value: testGroup - format: - property-version: 1 - type: json - schema: "ROW(rideId LONG, lon FLOAT, lat FLOAT, rideTime TIMESTAMP)" {% endhighlight %} -The resulting schema of the `TaxiRide` table contains most of the fields of the JSON schema. Furthermore, it adds a rowtime attribute `rowTime` and processing-time attribute `procTime`. Both `connector` and `format` allow to define a property version (which is currently version `1`) for future backwards compatibility. - -{% top %} - -### Schema Properties - -The schema allows for describing the final appearance of a table. It specifies the final name, final type, and the origin of a field. The origin of a field might be important if the name of the field should differ from the input format. For instance, a field `name&field` should reference `nameField` from an Avro format. - -{% highlight yaml %} -schema: - - name: MyField1 - type: ... - - name: MyField2 - type: ... - - name: MyField3 - type: ... -{% endhighlight %} - -For *each field*, the following properties can be used: - -{% highlight yaml %} -name: ... # required: final name of the field -type: ... # required: final type of the field represented as a type string -proctime: ... # optional: boolean flag whether this field should be a processing-time attribute -rowtime: ... # optional: wether this field should be a event-time attribute -from: ... # optional: original field in the input that is referenced/aliased by this field -{% endhighlight %} - -#### Type Strings - -The following type strings are supported for being defined in an environment file: - -{% highlight yaml %} -VARCHAR -BOOLEAN -TINYINT -SMALLINT -INT -BIGINT -FLOAT -DOUBLE -DECIMAL -DATE -TIME -TIMESTAMP -ROW(fieldtype, ...) # unnamed row; e.g. ROW(VARCHAR, INT) that is mapped to Flink's RowTypeInfo - # with indexed fields names f0, f1, ... -ROW(fieldname fieldtype, ...) # named row; e.g., ROW(myField VARCHAR, myOtherField INT) that - # is mapped to Flink's RowTypeInfo -POJO(class) # e.g., POJO(org.mycompany.MyPojoClass) that is mapped to Flink's PojoTypeInfo -ANY(class) # e.g., ANY(org.mycompany.MyClass) that is mapped to Flink's GenericTypeInfo -ANY(class, serialized) # used for type information that is not supported by Flink's Table & SQL API -{% endhighlight %} - -#### Rowtime Properties - -In order to control the event-time behavior for table sources, the SQL Client provides predefined timestamp extractors and watermark strategies. For more information about time handling in Flink and especially event-time, we recommend the general [event-time section](streaming.html#time-attributes). - -The following timestamp extractors are supported: - -{% highlight yaml %} -# Converts an existing BIGINT or TIMESTAMP field in the input into the rowtime attribute. -rowtime: - timestamps: - type: from-field - from: ... # required: original field name in the input - -# Converts the assigned timestamps from a DataStream API record into the rowtime attribute -# and thus preserves the assigned timestamps from the source. -rowtime: - timestamps: - type: from-source -{% endhighlight %} - -The following watermark strategies are supported: - -{% highlight yaml %} -# Sets a watermark strategy for ascending rowtime attributes. Emits a watermark of the maximum -# observed timestamp so far minus 1. Rows that have a timestamp equal to the max timestamp -# are not late. -rowtime: - watermarks: - type: periodic-ascending - -# Sets a built-in watermark strategy for rowtime attributes which are out-of-order by a bounded time interval. -# Emits watermarks which are the maximum observed timestamp minus the specified delay. -rowtime: - watermarks: - type: periodic-bounded - delay: ... # required: delay in milliseconds - -# Sets a built-in watermark strategy which indicates the watermarks should be preserved from the -# underlying DataStream API and thus preserves the assigned watermarks from the source. -rowtime: - watermarks: - type: from-source -{% endhighlight %} - -{% top %} - -### Connector Properties - -Flink provides a set of connectors that can be defined in the environment file. - -<span class="label label-danger">Attention</span> Currently, connectors can only be used as table sources not sinks. - -#### Filesystem Connector - -The filesystem connector allows for reading from a local or distributed filesystem. A filesystem can be defined as: - -{% highlight yaml %} -connector: - type: filesystem - path: "file:///path/to/whatever" # required -{% endhighlight %} - -Currently, only files with CSV format can be read from a filesystem. The filesystem connector is included in Flink and does not require an additional JAR file. - -#### Kafka Connector - -The Kafka connector allows for reading from a Apache Kafka topic. It can be defined as follows: - -{% highlight yaml %} -connector: - type: kafka - version: 0.11 # required: valid connector versions are "0.8", "0.9", "0.10", and "0.11" - topic: ... # required: topic name from which the table is read - startup-mode: ... # optional: valid modes are "earliest-offset", "latest-offset", - # "group-offsets", or "specific-offsets" - specific-offsets: # optional: used in case of startup mode with specific offsets - - partition: 0 - offset: 42 - - partition: 1 - offset: 300 - properties: # optional: connector specific properties - - key: zookeeper.connect - value: localhost:2181 - - key: bootstrap.servers - value: localhost:9092 - - key: group.id - value: testGroup -{% endhighlight %} - -Make sure to download the [Kafka SQL JAR](sqlClient.html#dependencies) file and pass it to the SQL Client. - -{% top %} - -### Format Properties - -Flink provides a set of formats that can be defined in the environment file. - -#### CSV Format - -The CSV format allows to read comma-separated rows. Currently, this is only supported for the filesystem connector. - -{% highlight yaml %} -format: - type: csv - fields: # required: format fields - - name: field1 - type: VARCHAR - - name: field2 - type: TIMESTAMP - field-delimiter: "," # optional: string delimiter "," by default - line-delimiter: "\n" # optional: string delimiter "\n" by default - quote-character: '"' # optional: single character for string values, empty by default - comment-prefix: '#' # optional: string to indicate comments, empty by default - ignore-first-line: false # optional: boolean flag to ignore the first line, by default it is not skipped - ignore-parse-errors: true # optional: skip records with parse error instead to fail by default -{% endhighlight %} - -The CSV format is included in Flink and does not require an additional JAR file. - -#### JSON Format - -The JSON format allows to read and write JSON data that corresponds to a given format schema. The format schema can be defined either as a Flink [type string](sqlClient.html#type-strings), as a JSON schema, or derived from the desired table schema. A type string enables a more SQL-like definition and mapping to the corresponding SQL data types. The JSON schema allows for more complex and nested structures. - -If the format schema is equal to the table schema, the schema can also be automatically derived. This allows for defining schema information only once. The names, types, and field order of the format are determined by the table's schema. Time attributes are ignored. A `from` definition in the table schema is interpreted as a field renaming in the format. - -{% highlight yaml %} -format: - type: json - fail-on-missing-field: true # optional: flag whether to fail if a field is missing or not - - # required: define the schema either by using a type string which parses numbers to corresponding types - schema: "ROW(lon FLOAT, rideTime TIMESTAMP)" - - # or by using a JSON schema which parses to DECIMAL and TIMESTAMP - json-schema: > - { - type: 'object', - properties: { - lon: { - type: 'number' - }, - rideTime: { - type: 'string', - format: 'date-time' - } - } - } - - # or use the tables schema - derive-schema: true -{% endhighlight %} - -The following table shows the mapping of JSON schema types to Flink SQL types: - -| JSON schema | Flink SQL | -| :-------------------------------- | :---------------------- | -| `object` | `ROW` | -| `boolean` | `BOOLEAN` | -| `array` | `ARRAY[_]` | -| `number` | `DECIMAL` | -| `integer` | `DECIMAL` | -| `string` | `VARCHAR` | -| `string` with `format: date-time` | `TIMESTAMP` | -| `string` with `format: date` | `DATE` | -| `string` with `format: time` | `TIME` | -| `string` with `encoding: base64` | `ARRAY[TINYINT]` | -| `null` | `NULL` (unsupported yet)| - - -Currently, Flink supports only a subset of the [JSON schema specification](http://json-schema.org/) `draft-07`. Union types (as well as `allOf`, `anyOf`, `not`) are not supported yet. `oneOf` and arrays of types are only supported for specifying nullability. - -Simple references that link to a common definition in the document are supported as shown in the more complex example below: - -{% highlight json %} -{ - "definitions": { - "address": { - "type": "object", - "properties": { - "street_address": { - "type": "string" - }, - "city": { - "type": "string" - }, - "state": { - "type": "string" - } - }, - "required": [ - "street_address", - "city", - "state" - ] - } - }, - "type": "object", - "properties": { - "billing_address": { - "$ref": "#/definitions/address" - }, - "shipping_address": { - "$ref": "#/definitions/address" - }, - "optional_address": { - "oneOf": [ - { - "type": "null" - }, - { - "$ref": "#/definitions/address" - } - ] - } - } -} -{% endhighlight %} - -Make sure to download the [JSON SQL JAR](sqlClient.html#dependencies) file and pass it to the SQL Client. - -#### Apache Avro Format - -The [Apache Avro](https://avro.apache.org/) format allows to read and write Avro data that corresponds to a given format schema. The format schema can be defined either as a fully qualified class name of an Avro specific record or as an Avro schema string. If a class name is used, the class must be available in the classpath during runtime. - -{% highlight yaml %} -format: - type: avro - - # required: define the schema either by using an Avro specific record class - record-class: "org.organization.types.User" - - # or by using an Avro schema - avro-schema: > - { - "type": "record", - "name": "test", - "fields" : [ - {"name": "a", "type": "long"}, - {"name": "b", "type": "string"} - ] - } -{% endhighlight %} +The resulting schema of the `TaxiRide` table contains most of the fields of the JSON schema. Furthermore, it adds a rowtime attribute `rowTime` and processing-time attribute `procTime`. -Avro types are mapped to the corresponding SQL data types. Union types are only supported for specifying nullability otherwise they are converted to an `ANY` type. The following table shows the mapping: - -| Avro schema | Flink SQL | -| :------------------------------------------ | :---------------------- | -| `record` | `ROW` | -| `enum` | `VARCHAR` | -| `array` | `ARRAY[_]` | -| `map` | `MAP[VARCHAR, _]` | -| `union` | non-null type or `ANY` | -| `fixed` | `ARRAY[TINYINT]` | -| `string` | `VARCHAR` | -| `bytes` | `ARRAY[TINYINT]` | -| `int` | `INT` | -| `long` | `BIGINT` | -| `float` | `FLOAT` | -| `double` | `DOUBLE` | -| `boolean` | `BOOLEAN` | -| `int` with `logicalType: date` | `DATE` | -| `int` with `logicalType: time-millis` | `TIME` | -| `int` with `logicalType: time-micros` | `INT` | -| `long` with `logicalType: timestamp-millis` | `TIMESTAMP` | -| `long` with `logicalType: timestamp-micros` | `BIGINT` | -| `bytes` with `logicalType: decimal` | `DECIMAL` | -| `fixed` with `logicalType: decimal` | `DECIMAL` | -| `null` | `NULL` (unsupported yet)| - -Avro uses [Joda-Time](http://www.joda.org/joda-time/) for representing logical date and time types in specific record classes. The Joda-Time dependency is not part of Flink's SQL JAR distribution. Therefore, make sure that Joda-Time is in your classpath together with your specific record class during runtime. Avro formats specified via a schema string do not require Joda-Time to be present. - -Make sure to download the [Apache Avro SQL JAR](sqlClient.html#dependencies) file and pass it to the SQL Client. +Both `connector` and `format` allow to define a property version (which is currently version `1`) for future backwards compatibility. {% top %} diff --git a/flink-formats/flink-json/src/main/java/org/apache/flink/table/descriptors/Json.java b/flink-formats/flink-json/src/main/java/org/apache/flink/table/descriptors/Json.java index 035f05f7cd5..026f49e611c 100644 --- a/flink-formats/flink-json/src/main/java/org/apache/flink/table/descriptors/Json.java +++ b/flink-formats/flink-json/src/main/java/org/apache/flink/table/descriptors/Json.java @@ -96,8 +96,8 @@ public Json schema(TypeInformation<Row> schemaType) { * <p>This allows for defining schema information only once. * * <p>The names, types, and field order of the format are determined by the table's - * schema. Time attributes are ignored. A "from" definition is interpreted as a field renaming - * in the format. + * schema. Time attributes are ignored if their origin is not a field. A "from" definition + * is interpreted as a field renaming in the format. */ public Json deriveSchema() { this.deriveSchema = true; ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services
