dawidwys commented on a change in pull request #8006: [FLINK-11068][table] Convert the API classes of *Table to interfaces URL: https://github.com/apache/flink/pull/8006#discussion_r266773007
########## File path: flink-table/flink-table-api-java/src/main/java/org/apache/flink/table/api/Table.java ########## @@ -0,0 +1,922 @@ +/* + * 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. + */ + +package org.apache.flink.table.api; + +import org.apache.flink.annotation.PublicEvolving; +import org.apache.flink.table.expressions.Expression; +import org.apache.flink.table.functions.TableFunction; +import org.apache.flink.table.functions.TemporalTableFunction; +import org.apache.flink.table.sinks.TableSink; + +/** + * A Table is the core component of the Table API. + * Similar to how the batch and streaming APIs have DataSet and DataStream, + * the Table API is built around {@link Table}. + * + * <p>Use the methods of {@link Table} to transform data. Use {@code TableEnvironment} to convert a + * {@link Table} back to a {@code DataSet} or {@code DataStream}. + * + * <p>When using Scala a {@link Table} can also be converted using implicit conversions. + * + * <p>Java Example: + * + * <pre> + * {@code + * ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment(); + * BatchTableEnvironment tEnv = BatchTableEnvironment.create(env); + * + * DataSet<Tuple2<String, Integer>> set = ... + * tEnv.registerTable("MyTable", set, "a, b"); + * + * Table table = tEnv.scan("MyTable").select(...); + * ... + * Table table2 = ... + * DataSet<MyType> set2 = tEnv.toDataSet(table2, MyType.class); + * } + * </pre> + * + * <p>Scala Example: + * + * <pre> + * {@code + * val env = ExecutionEnvironment.getExecutionEnvironment + * val tEnv = BatchTableEnvironment.create(env) + * + * val set: DataSet[(String, Int)] = ... + * val table = set.toTable(tEnv, 'a, 'b) + * ... + * val table2 = ... + * val set2: DataSet[MyType] = table2.toDataSet[MyType] + * } + * </pre> + * + * <p>Operations such as {@code join}, {@code select}, {@code where} and {@code groupBy} either + * take arguments in a Scala DSL or as an expression String. Please refer to the documentation for + * the expression syntax. + * + */ +@PublicEvolving +public interface Table { + + /** + * Returns the schema of this table. + */ + TableSchema getSchema(); + + /** + * Prints the schema of this table to the console in a tree format. + */ + void printSchema(); + + /** + * Performs a selection operation. Similar to an SQL SELECT statement. The field expressions + * can contain complex expressions and aggregations. + * + * <p>Example: + * + * <pre> + * {@code + * tab.select("key, value.avg + ' The average' as average") + * } + * </pre> + */ + Table select(String fields); + + /** + * Performs a selection operation. Similar to an SQL SELECT statement. The field expressions + * can contain complex expressions and aggregations. + * + * <p>Example: + * + * <pre> + * {@code + * tab.select('key, 'value.avg + " The average" as 'average) + * } + * </pre> + */ + Table select(Expression... fields); + + /** + * Creates {@link TemporalTableFunction} backed up by this table as a history table. + * Temporal Tables represent a concept of a table that changes over time and for which + * Flink keeps track of those changes. {@link TemporalTableFunction} provides a way how to + * access those data. + * + * <p>For more information please check Flink's documentation on Temporal Tables. + * + * <p>Currently {@link TemporalTableFunction}s are only supported in streaming. + * + * @param timeAttribute Must points to a time attribute. Provides a way to compare which + * records are a newer or older version. + * @param primaryKey Defines the primary key. With primary key it is possible to update + * a row or to delete it. + * @return {@link TemporalTableFunction} which is an instance of {@link TableFunction}. + * It takes one single argument, the {@code timeAttribute}, for which it returns + * matching version of the {@link Table}, from which {@link TemporalTableFunction} + * was created. + */ + TemporalTableFunction createTemporalTableFunction(String timeAttribute, String primaryKey); + + /** + * Creates {@link TemporalTableFunction} backed up by this table as a history table. + * Temporal Tables represent a concept of a table that changes over time and for which + * Flink keeps track of those changes. {@link TemporalTableFunction} provides a way how to + * access those data. + * + * <p>For more information please check Flink's documentation on Temporal Tables. + * + * <p>Currently {@link TemporalTableFunction}s are only supported in streaming. + * + * @param timeAttribute Must points to a time indicator. Provides a way to compare which + * records are a newer or older version. + * @param primaryKey Defines the primary key. With primary key it is possible to update + * a row or to delete it. + * @return {@link TemporalTableFunction} which is an instance of {@link TableFunction}. + * It takes one single argument, the {@code timeAttribute}, for which it returns + * matching version of the {@link Table}, from which {@link TemporalTableFunction} + * was created. + */ + TemporalTableFunction createTemporalTableFunction(Expression timeAttribute, Expression primaryKey); + + /** + * Renames the fields of the expression result. Use this to disambiguate fields before + * joining to operations. + * + * <p>Example: + * + * <pre> + * {@code + * tab.as("a, b") + * } + * </pre> + */ + Table as(String fields); + + /** + * Renames the fields of the expression result. Use this to disambiguate fields before + * joining to operations. + * + * <p>Example: + * + * <pre> + * {@code + * tab.as('a, 'b) + * } + * </pre> + */ + Table as(Expression... fields); + + /** + * Filters out elements that don't pass the filter predicate. Similar to a SQL WHERE + * clause. + * + * <p>Example: + * + * <pre> + * {@code + * tab.filter("name = 'Fred'") + * } + * </pre> + */ + Table filter(String predicate); + + /** + * Filters out elements that don't pass the filter predicate. Similar to a SQL WHERE + * clause. + * + * <p>Example: + * + * <pre> + * {@code + * tab.filter('name === "Fred") + * } + * </pre> + */ + Table filter(Expression predicate); + + /** + * Filters out elements that don't pass the filter predicate. Similar to a SQL WHERE + * clause. + * + * <p>Example: + * + * <pre> + * {@code + * tab.where("name = 'Fred'") + * } + * </pre> + */ + Table where(String predicate); + + /** + * Filters out elements that don't pass the filter predicate. Similar to a SQL WHERE + * clause. + * + * <p>Example: + * + * <pre> + * {@code + * tab.where('name === "Fred") + * } + * </pre> + */ + Table where(Expression predicate); + + /** + * Groups the elements on some grouping keys. Use this before a selection with aggregations + * to perform the aggregation on a per-group basis. Similar to a SQL GROUP BY statement. + * + * <p>Example: + * + * <pre> + * {@code + * tab.groupBy("key").select("key, value.avg") + * } + * </pre> + */ + GroupedTable groupBy(String fields); + + /** + * Groups the elements on some grouping keys. Use this before a selection with aggregations + * to perform the aggregation on a per-group basis. Similar to a SQL GROUP BY statement. + * + * <p>Example: + * + * <pre> + * {@code + * tab.groupBy('key).select('key, 'value.avg) + * } + * </pre> + */ + GroupedTable groupBy(Expression... fields); + + /** + * Removes duplicate values and returns only distinct (different) values. + * + * <p>Example: + * + * <pre> + * {@code + * tab.select("key, value").distinct() + * } + * </pre> + */ + Table distinct(); + + /** + * Joins two {@link Table}s. Similar to an SQL join. The fields of the two joined + * operations must not overlap, use {@code as} to rename fields if necessary. You can use + * where and select clauses after a join to further specify the behaviour of the join. + * + * <p>Note: Both tables must be bound to the same {@code TableEnvironment} . + * + * <p>Example: + * + * <pre> + * {@code + * left.join(right).where('a === 'b && 'c > 3).select('a, 'b, 'd) + * } + * </pre> + */ + Table join(Table right); + + /** + * Joins two {@link Table}s. Similar to an SQL join. The fields of the two joined + * operations must not overlap, use {@code as} to rename fields if necessary. + * + * <p>Note: Both tables must be bound to the same {@code TableEnvironment} . + * + * <p>Example: + * + * <pre> + * {@code + * left.join(right, "a = b") + * } + * </pre> + */ + Table join(Table right, String joinPredicate); + + /** + * Joins two {@link Table}s. Similar to an SQL join. The fields of the two joined + * operations must not overlap, use {@code as} to rename fields if necessary. + * + * <p>Note: Both tables must be bound to the same {@code TableEnvironment} . + * + * <p>Example: + * + * <pre> + * {@code + * left.join(right, 'a === 'b).select('a, 'b, 'd) + * } + * </pre> + */ + Table join(Table right, Expression joinPredicate); + + /** + * Joins two {@link Table}s. Similar to an SQL left outer join. The fields of the two joined + * operations must not overlap, use {@code as} to rename fields if necessary. + * + * <p>Note: Both tables must be bound to the same {@code TableEnvironment} and its + * {@code TableConfig} must have null check enabled (default). + * + * <p>Example: + * + * <pre> + * {@code + * left.leftOuterJoin(right).select('a, 'b, 'd) + * } + * </pre> + */ + Table leftOuterJoin(Table right); + + /** + * Joins two {@link Table}s. Similar to an SQL left outer join. The fields of the two joined + * operations must not overlap, use {@code as} to rename fields if necessary. + * + * <p>Note: Both tables must be bound to the same {@code TableEnvironment} and its + * {@code TableConfig} must have null check enabled (default). + * + * <p>Example: + * + * <pre> + * {@code + * left.leftOuterJoin(right, "a = b").select("a, b, d") + * } + * </pre> + */ + Table leftOuterJoin(Table right, String joinPredicate); + + /** + * Joins two {@link Table}s. Similar to an SQL left outer join. The fields of the two joined + * operations must not overlap, use {@code as} to rename fields if necessary. + * + * <p>Note: Both tables must be bound to the same {@code TableEnvironment} and its + * {@code TableConfig} must have null check enabled (default). + * + * <p>Example: + * + * <pre> + * {@code + * left.leftOuterJoin(right, 'a === 'b).select('a, 'b, 'd) + * } + * </pre> + */ + Table leftOuterJoin(Table right, Expression joinPredicate); + + /** + * Joins two {@link Table}s. Similar to an SQL right outer join. The fields of the two joined + * operations must not overlap, use {@code as} to rename fields if necessary. + * + * <p>Note: Both tables must be bound to the same {@code TableEnvironment} and its + * {@code TableConfig} must have null check enabled (default). + * + * <p>Example: + * + * <pre> + * {@code + * left.rightOuterJoin(right, "a = b").select('a, 'b, 'd) + * } + * </pre> + */ + Table rightOuterJoin(Table right, String joinPredicate); + + /** + * Joins two {@link Table}s. Similar to an SQL right outer join. The fields of the two joined + * operations must not overlap, use {@code as} to rename fields if necessary. + * + * <p>Note: Both tables must be bound to the same {@code TableEnvironment} and its + * {@code TableConfig} must have null check enabled (default). + * + * <p>Example: + * + * <pre> + * {@code + * left.rightOuterJoin(right, 'a === 'b).select('a, 'b, 'd) + * } + * </pre> + */ + Table rightOuterJoin(Table right, Expression joinPredicate); + + /** + * Joins two {@link Table}s. Similar to an SQL full outer join. The fields of the two joined + * operations must not overlap, use {@code as} to rename fields if necessary. + * + * <p>Note: Both tables must be bound to the same {@code TableEnvironment} and its + * {@code TableConfig} must have null check enabled (default). + * + * <p>Example: + * + * <pre> + * {@code + * left.fullOuterJoin(right, "a = b").select('a, 'b, 'd) + * } + * </pre> + */ + Table fullOuterJoin(Table right, String joinPredicate); + + /** + * Joins two {@link Table}s. Similar to an SQL full outer join. The fields of the two joined + * operations must not overlap, use {@code as} to rename fields if necessary. + * + * <p>Note: Both tables must be bound to the same {@code TableEnvironment} and its + * {@code TableConfig} must have null check enabled (default). + * + * <p>Example: + * + * <pre> + * {@code + * left.fullOuterJoin(right, 'a === 'b).select('a, 'b, 'd) + * } + * </pre> + */ + Table fullOuterJoin(Table right, Expression joinPredicate); + + /** + * Joins this {@link Table} with an user-defined {@link TableFunction}. This join is similar to + * a SQL inner join with ON TRUE predicate but works with a table function. Each row of the + * table is joined with all rows produced by the table function. + * + * <p>Example: + * + * <pre> + * {@code + * class MySplitUDTF extends TableFunction<String> { + * public void eval(String str) { + * str.split("#").forEach(this::collect); + * } + * } + * + * TableFunction<String> split = new MySplitUDTF(); + * tableEnv.registerFunction("split", split); + * table.joinLateral("split(c) as (s)").select("a, b, c, s"); + * } + * </pre> + */ + Table joinLateral(String tableFunctionCall); + + /** + * Joins this {@link Table} with an user-defined {@link TableFunction}. This join is similar to + * a SQL inner join with ON TRUE predicate but works with a table function. Each row of the + * table is joined with all rows produced by the table function. + * + * <p>Example: + * + * <pre> + * {@code + * class MySplitUDTF extends TableFunction[String] { + * def eval(str: String): Unit = { + * str.split("#").foreach(collect) + * } + * } + * + * val split = new MySplitUDTF() + * table.joinLateral(split('c) as ('s)).select('a, 'b, 'c, 's) + * } + * </pre> + */ + Table joinLateral(Expression tableFunctionCall); + + /** + * Joins this {@link Table} with an user-defined {@link TableFunction}. This join is similar to + * a SQL inner join with ON TRUE predicate but works with a table function. Each row of the + * table is joined with all rows produced by the table function. + * + * <p>Example: + * + * <pre> + * {@code + * class MySplitUDTF extends TableFunction<String> { + * public void eval(String str) { + * str.split("#").forEach(this::collect); + * } + * } + * + * TableFunction<String> split = new MySplitUDTF(); + * tableEnv.registerFunction("split", split); + * table.joinLateral("split(c) as (s)", "a = s").select("a, b, c, s"); + * } + * </pre> + */ + Table joinLateral(String tableFunctionCall, String joinPredicate); + + /** + * Joins this {@link Table} with an user-defined {@link TableFunction}. This join is similar to + * a SQL inner join with ON TRUE predicate but works with a table function. Each row of the + * table is joined with all rows produced by the table function. + * + * <p>Example: + * + * <pre> + * {@code + * class MySplitUDTF extends TableFunction[String] { + * def eval(str: String): Unit = { + * str.split("#").foreach(collect) + * } + * } + * + * val split = new MySplitUDTF() + * table.joinLateral(split('c) as ('s), 'a === 's).select('a, 'b, 'c, 's) + * } + * </pre> + */ + Table joinLateral(Expression tableFunctionCall, Expression joinPredicate); + + /** + * Joins this {@link Table} with an user-defined {@link TableFunction}. This join is similar to + * a SQL left outer join with ON TRUE predicate but works with a table function. Each row of + * the table is joined with all rows produced by the table function. If the table function does + * not produce any row, the outer row is padded with nulls. + * + * <p>Example: + * + * <pre> + * {@code + * class MySplitUDTF extends TableFunction<String> { + * public void eval(String str) { + * str.split("#").forEach(this::collect); + * } + * } + * + * TableFunction<String> split = new MySplitUDTF(); + * tableEnv.registerFunction("split", split); + * table.leftOuterJoinLateral("split(c) as (s)").select("a, b, c, s"); + * } + * </pre> + */ + Table leftOuterJoinLateral(String tableFunctionCall); + + /** + * Joins this {@link Table} with an user-defined {@link TableFunction}. This join is similar to + * a SQL left outer join with ON TRUE predicate but works with a table function. Each row of + * the table is joined with all rows produced by the table function. If the table function does + * not produce any row, the outer row is padded with nulls. + * + * <p>Example: + * + * <pre> + * {@code + * class MySplitUDTF extends TableFunction[String] { + * def eval(str: String): Unit = { + * str.split("#").foreach(collect) + * } + * } + * + * val split = new MySplitUDTF() + * table.leftOuterJoinLateral(split('c) as ('s)).select('a, 'b, 'c, 's) + * } + * </pre> + */ + Table leftOuterJoinLateral(Expression tableFunctionCall); + + /** + * Joins this {@link Table} with an user-defined {@link TableFunction}. This join is similar to + * a SQL left outer join with ON TRUE predicate but works with a table function. Each row of + * the table is joined with all rows produced by the table function. If the table function does + * not produce any row, the outer row is padded with nulls. + * + * <p>Example: + * + * <pre> + * {@code + * class MySplitUDTF extends TableFunction<String> { + * public void eval(String str) { + * str.split("#").forEach(this::collect); + * } + * } + * + * TableFunction<String> split = new MySplitUDTF(); + * tableEnv.registerFunction("split", split); + * table.leftOuterJoinLateral("split(c) as (s)", "a = s").select("a, b, c, s"); + * } + * </pre> + */ + Table leftOuterJoinLateral(String tableFunctionCall, String joinPredicate); + + /** + * Joins this {@link Table} with an user-defined {@link TableFunction}. This join is similar to + * a SQL left outer join with ON TRUE predicate but works with a table function. Each row of + * the table is joined with all rows produced by the table function. If the table function does + * not produce any row, the outer row is padded with nulls. + * + * <p>Example: + * + * <pre> + * {@code + * class MySplitUDTF extends TableFunction[String] { + * def eval(str: String): Unit = { + * str.split("#").foreach(collect) + * } + * } + * + * val split = new MySplitUDTF() + * table.leftOuterJoinLateral(split('c) as ('s), 'a === 's).select('a, 'b, 'c, 's) + * } + * </pre> + */ + Table leftOuterJoinLateral(Expression tableFunctionCall, Expression joinPredicate); + + /** + * Minus of two {@link Table}s with duplicate records removed. + * Similar to a SQL EXCEPT clause. Minus returns records from the left table that do not + * exist in the right table. Duplicate records in the left table are returned + * exactly once, i.e., duplicates are removed. Both tables must have identical field types. + * + * <p>Note: Both tables must be bound to the same {@code TableEnvironment}. + * + * <p>Example: + * + * <pre> + * {@code + * left.minus(right) + * } + * </pre> + */ + Table minus(Table right); + + /** + * Minus of two {@link Table}s. Similar to an SQL EXCEPT ALL. + * Similar to a SQL EXCEPT ALL clause. MinusAll returns the records that do not exist in + * the right table. A record that is present n times in the left table and m times + * in the right table is returned (n - m) times, i.e., as many duplicates as are present + * in the right table are removed. Both tables must have identical field types. + * + * <p>Note: Both tables must be bound to the same {@code TableEnvironment}. + * + * <p>Example: + * + * <pre> + * {@code + * left.minusAll(right) + * } + * </pre> + */ + Table minusAll(Table right); + + /** + * Unions two {@link Table}s with duplicate records removed. + * Similar to an SQL UNION. The fields of the two union operations must fully overlap. + * + * <p>Note: Both tables must be bound to the same {@code TableEnvironment}. + * + * <p>Example: + * + * <pre> + * {@code + * left.union(right) + * } + * </pre> + */ + Table union(Table right); + + /** + * Unions two {@link Table}s. Similar to an SQL UNION ALL. The fields of the two union + * operations must fully overlap. + * + * <p>Note: Both tables must be bound to the same {@code TableEnvironment}. + * + * <p>Example: + * + * <pre> + * {@code + * left.unionAll(right) + * } + * </pre> + */ + Table unionAll(Table right); + + /** + * Intersects two {@link Table}s with duplicate records removed. Intersect returns records that + * exist in both tables. If a record is present in one or both tables more than once, it is + * returned just once, i.e., the resulting table has no duplicate records. Similar to an + * SQL INTERSECT. The fields of the two intersect operations must fully overlap. + * + * <p>Note: Both tables must be bound to the same {@code TableEnvironment}. + * + * <p>Example: + * + * <pre> + * {@code + * left.intersect(right) + * } + * </pre> + */ + Table intersect(Table right); + + /** + * Intersects two {@link Table}s. IntersectAll returns records that exist in both tables. + * If a record is present in both tables more than once, it is returned as many times as it + * is present in both tables, i.e., the resulting table might have duplicate records. Similar + * to an SQL INTERSECT ALL. The fields of the two intersect operations must fully overlap. + * + * <p>Note: Both tables must be bound to the same {@code TableEnvironment}. + * + * <p>Example: + * + * <pre> + * {@code + * left.intersectAll(right) + * } + * </pre> + */ + Table intersectAll(Table right); + + /** + * Sorts the given {@link Table}. Similar to SQL ORDER BY. + * The resulting Table is sorted globally sorted across all parallel partitions. + * + * <p>Example: + * + * <pre> + * {@code + * tab.orderBy("name.desc") + * } + * </pre> + */ + Table orderBy(String fields); + + /** + * Sorts the given {@link Table}. Similar to SQL ORDER BY. + * The resulting Table is globally sorted across all parallel partitions. + * + * <p>Example: + * + * <pre> + * {@code + * tab.orderBy('name.desc) + * } + * </pre> + */ + Table orderBy(Expression... fields); + + /** + * Limits a sorted result from an offset position. + * Similar to a SQL OFFSET clause. Offset is technically part of the Order By operator and + * thus must be preceded by it. + * + * {@link Table#offset(Integer offset)} can be combined with a subsequent + * {@link Table#fetch(Integer fetch)} call to return n rows after skipping the first o rows. + * + * <pre> + * {@code + * // skips the first 3 rows and returns all following rows. + * tab.orderBy('name.desc).offset(3) + * // skips the first 10 rows and returns the next 5 rows. + * tab.orderBy('name.desc).offset(10).fetch(5) + * } + * </pre> + * + * @param offset number of records to skip + */ + Table offset(Integer offset); + + /** + * Limits a sorted result to the first n rows. + * Similar to a SQL FETCH clause. Fetch is technically part of the Order By operator and + * thus must be preceded by it. + * + * {@link Table#fetch(Integer fetch)} can be combined with a preceding + * {@link Table#offset(Integer offset)} call to return n rows after skipping the first o rows. + * + * <pre> + * {@code + * // returns the first 3 records. + * tab.orderBy('name.desc).fetch(3) + * // skips the first 10 rows and returns the next 5 rows. + * tab.orderBy('name.desc).offset(10).fetch(5) + * } + * </pre> + * + * @param fetch the number of records to return. Fetch must be >= 0. + */ + Table fetch(Integer fetch); + + /** + * Writes the {@link Table} to a {@link TableSink}. A {@link TableSink} defines an external + * storage location. + * + * <p>A batch {@link Table} can only be written to a + * {@code org.apache.flink.table.sinks.BatchTableSink}, a streaming {@link Table} requires a + * {@code org.apache.flink.table.sinks.AppendStreamTableSink}, a + * {@code org.apache.flink.table.sinks.RetractStreamTableSink}, or an + * {@code org.apache.flink.table.sinks.UpsertStreamTableSink}. + * + * @param sink The {@link TableSink} to which the {@link Table} is written. + * @tparam T The data type that the {@link TableSink} expects. + * + * @deprecated Will be removed in a future release. Please register the TableSink and use + * {@link Table#insertInto(String tableName)}. + */ + @Deprecated + <T> void writeToSink(TableSink<T> sink); Review comment: Maybe let's just drop it since it's deprecated since 1.7? ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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