wuchong commented on a change in pull request #12523: URL: https://github.com/apache/flink/pull/12523#discussion_r437120149
########## File path: docs/dev/table/connectors/formats/avro.md ########## @@ -0,0 +1,206 @@ +--- +title: "Avro Format" +nav-title: Avro +nav-parent_id: sql-formats +nav-pos: 3 +--- +<!-- +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. +--> + +<span class="label label-info">Format: Serialization Schema</span> +<span class="label label-info">Format: Deserialization Schema</span> + +* This will be replaced by the TOC +{:toc} + +The [Apache Avro](https://avro.apache.org/) format allows to read and write Avro data based on an Avro schema. Currently, the Avro schema is derived from table schema. + +Dependencies +------------ + +In order to setup the Avro format, the following table provide dependency information for both projects using a build automation tool (such as Maven or SBT) and SQL Client with SQL JAR bundles. + +| Maven dependency | SQL Client JAR | +| :----------------- | :----------------------| +| `flink-avro` | [Pre-bundled Hadoop](https://flink.apache.org/downloads.html#additional-components) | + +How to create a table with Avro format +---------------- + +Here is an example to create a table using Kafka connector and Avro format. + +<div class="codetabs" markdown="1"> +<div data-lang="SQL" markdown="1"> +{% highlight sql %} +CREATE TABLE user_behavior ( + user_id BIGINT, + item_id BIGINT, + category_id BIGINT, + behavior STRING, + ts TIMESTAMP(3), +) WITH ( + 'connector' = 'kafka', + 'topic' = 'user_behavior', + 'properties.bootstrap.servers' = 'localhost:9092', + 'properties.group.id' = 'testGroup', + 'format' = 'avro' +) +{% endhighlight %} +</div> +</div> + +Format Options +---------------- + +<table class="table table-bordered"> + <thead> + <tr> + <th class="text-left" style="width: 25%">Option</th> + <th class="text-center" style="width: 8%">Required</th> + <th class="text-center" style="width: 7%">Default</th> + <th class="text-center" style="width: 10%">Type</th> + <th class="text-center" style="width: 50%">Description</th> + </tr> + </thead> + <tbody> + <tr> + <td><h5>format</h5></td> + <td>required</td> + <td style="word-wrap: break-word;">(none)</td> + <td>String</td> + <td>Specify what format to use, here should be 'avro'.</td> + </tr> + </tbody> +</table> + +Data Type Mapping +---------------- + +Currently, the Avro schema is always derived from table schema, explicitly define an Avro schema is not supported yet. So here only lists the conversion from Flink type to Avro type. + +### Conversion from Flink type to Avro type + +The following table lists the conversion from the supported Flink type to Avro type. + +<table class="table table-bordered"> + <thead> + <tr> + <th class="text-left">Flink Data Type</th> + <th class="text-center">Avro type</th> + <th class="text-center">Avro logical type</th> + </tr> + </thead> + <tbody> + <tr> + <td>CHAR / VARCHAR / STRING</td> + <td>string</td> + <td></td> + </tr> + <tr> + <td>BOOLEAN</td> + <td>boolean</td> + <td></td> + </tr> + <tr> + <td>BINARY / VARBINARY</td> + <td>bytes</td> + <td></td> + </tr> + <tr> + <td>DECIMAL</td> + <td>fixed</td> + <td>decimal</td> + </tr> + <tr> + <td>TINYINT</td> + <td>int</td> + <td></td> + </tr> + <tr> + <td>SMALLINT</td> + <td>int</td> + <td></td> + </tr> + <tr> + <td>INT</td> + <td>int</td> + <td></td> + </tr> + <tr> + <td>BIGINT</td> + <td>long</td> + <td></td> + </tr> + <tr> + <td>FLOAT</td> + <td>float</td> + <td></td> + </tr> + <tr> + <td>DOUBLE</td> + <td>double</td> + <td></td> + </tr> + <tr> + <td>DATE</td> + <td>int</td> + <td>date</td> + </tr> + <tr> + <td>TIME</td> + <td>int</td> + <td>time-millis</td> + </tr> + <tr> + <td>TIMESTAMP</td> + <td>long</td> + <td>timestamp-millis</td> + </tr> + <tr> + <td>ARRAY</td> + <td>array</td> + <td></td> + </tr> + <tr> + <td>MAP<br> + (key must be string/char/varchar type)</td> + <td>map</td> + <td></td> + </tr> + <tr> + <td>MULTISET<br> + (element must be string/char/varchar type)</td> + <td>map</td> + <td></td> + </tr> + <tr> + <td>ROW</td> + <td>record</td> + <td></td> + </tr> + </tbody> +</table> + +In addition to the types listed above, Flink supports reading/writing nullable types. Flink maps nullable types to Avro `union(something, null)`, where `something` is any converted Avro type from Flink type. + Review comment: I changed this to ``` where `something` is the Avro type converted from Flink type. ``` ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: [email protected]
