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Table-valued Functions (TVF)
Table-valued Functions (TVF)
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.

Description

A table-valued function (TVF) is a function that returns a relation or a set of rows. There are two types of TVFs in Spark SQL:

  1. a TVF that can be specified in a FROM clause, e.g. range;
  2. a TVF that can be specified in SELECT/LATERAL VIEW clauses, e.g. explode.

Supported Table-valued Functions

TVFs that can be specified in a FROM clause:

Function Argument Type(s) Description
range ( end ) Long Creates a table with a single LongType column named id,
containing rows in a range from 0 to end (exclusive) with step value 1.
range ( start, end ) Long, Long Creates a table with a single LongType column named id,
containing rows in a range from start to end (exclusive) with step value 1.
range ( start, end, step ) Long, Long, Long Creates a table with a single LongType column named id,
containing rows in a range from start to end (exclusive) with step value.
range ( start, end, step, numPartitions ) Long, Long, Long, Int Creates a table with a single LongType column named id,
containing rows in a range from start to end (exclusive) with step value, with partition number numPartitions specified.
explode ( expr ) Array/Map Separates the elements of array expr into multiple rows, or the elements of map expr into multiple rows and columns. Unless specified otherwise, uses the default column name col for elements of the array or key and value for the elements of the map.
explode_outer
( expr )		 Array/Map Separates the elements of array expr into multiple rows, or the elements of map expr into multiple rows and columns. Unless specified otherwise, uses the default column name col for elements of the array or key and value for the elements of the map.
inline ( expr ) Expression Explodes an array of structs into a table. Uses column names col1, col2, etc. by default unless specified otherwise.
inline_outer
( expr )		 Expression Explodes an array of structs into a table. Uses column names col1, col2, etc. by default unless specified otherwise.
posexplode
( expr )		 Array/Map Separates the elements of array expr into multiple rows with positions, or the elements of map expr into multiple rows and columns with positions. Unless specified otherwise, uses the column name pos for position, col for elements of the array or key and value for elements of the map.
posexplode_outer ( expr ) Array/Map Separates the elements of array expr into multiple rows with positions, or the elements of map expr into multiple rows and columns with positions. Unless specified otherwise, uses the column name pos for position, col for elements of the array or key and value for elements of the map.
stack ( n, expr1, ..., exprk ) Seq[Expression] Separates expr1, ..., exprk into n rows. Uses column names col0, col1, etc. by default unless specified otherwise.
json_tuple
( jsonStr, p1, p2, ..., pn )		 Seq[Expression] Returns a tuple like the function get_json_object, but it takes multiple names. All the input parameters and output column types are string.
parse_url
( url, partToExtract[, key] )		 Seq[Expression] Extracts a part from a URL.

TVFs that can be specified in SELECT/LATERAL VIEW clauses:

Function Argument Type(s) Description
explode ( expr ) Array/Map Separates the elements of array expr into multiple rows, or the elements of map expr into multiple rows and columns. Unless specified otherwise, uses the default column name col for elements of the array or key and value for the elements of the map.
explode_outer
( expr )		 Array/Map Separates the elements of array expr into multiple rows, or the elements of map expr into multiple rows and columns. Unless specified otherwise, uses the default column name col for elements of the array or key and value for the elements of the map.
inline ( expr ) Expression Explodes an array of structs into a table. Uses column names col1, col2, etc. by default unless specified otherwise.
inline_outer
( expr )		 Expression Explodes an array of structs into a table. Uses column names col1, col2, etc. by default unless specified otherwise.
posexplode
( expr )		 Array/Map Separates the elements of array expr into multiple rows with positions, or the elements of map expr into multiple rows and columns with positions. Unless specified otherwise, uses the column name pos for position, col for elements of the array or key and value for elements of the map.
posexplode_outer ( expr ) Array/Map Separates the elements of array expr into multiple rows with positions, or the elements of map expr into multiple rows and columns with positions. Unless specified otherwise, uses the column name pos for position, col for elements of the array or key and value for elements of the map.
stack ( n, expr1, ..., exprk ) Seq[Expression] Separates expr1, ..., exprk into n rows. Uses column names col0, col1, etc. by default unless specified otherwise.
json_tuple
( jsonStr, p1, p2, ..., pn )		 Seq[Expression] Returns a tuple like the function get_json_object, but it takes multiple names. All the input parameters and output column types are string.
parse_url
( url, partToExtract[, key] )		 Seq[Expression] Extracts a part from a URL.

Examples

-- range call with end
SELECT * FROM range(6 + cos(3));
+---+
| id|
+---+
|  0|
|  1|
|  2|
|  3|
|  4|
+---+

-- range call with start and end
SELECT * FROM range(5, 10);
+---+
| id|
+---+
|  5|
|  6|
|  7|
|  8|
|  9|
+---+

-- range call with numPartitions
SELECT * FROM range(0, 10, 2, 200);
+---+
| id|
+---+
|  0|
|  2|
|  4|
|  6|
|  8|
+---+

-- range call with a table alias
SELECT * FROM range(5, 8) AS test;
+---+
| id|
+---+
|  5|
|  6|
|  7|
+---+

SELECT * FROM explode(array(10, 20));
+---+
|col|
+---+
| 10|
| 20|
+---+

SELECT * FROM inline(array(struct(1, 'a'), struct(2, 'b')));
+----+----+
|col1|col2|
+----+----+
|   1|   a|
|   2|   b|
+----+----+

SELECT * FROM posexplode(array(10,20));
+---+---+
|pos|col|
+---+---+
|  0| 10|
|  1| 20|
+---+---+

SELECT * FROM stack(2, 1, 2, 3);
+----+----+
|col0|col1|
+----+----+
|   1|   2|
|   3|null|
+----+----+

SELECT * FROM json_tuple('{"a":1, "b":2}', 'a', 'b');
+---+---+
| c0| c1|
+---+---+
|  1|  2|
+---+---+

SELECT parse_url('http://spark.apache.org/path?query=1', 'HOST');
+-----------------------------------------------------+
|parse_url(http://spark.apache.org/path?query=1, HOST)|
+-----------------------------------------------------+
|                                     spark.apache.org|
+-----------------------------------------------------+

-- Use explode with LATERAL join
CREATE TABLE test (c1 INT);
INSERT INTO test VALUES (1);
INSERT INTO test VALUES (2);
SELECT * FROM test, LATERAL explode (ARRAY(3,4)) AS c2;
+--+--+
|c1|c2|
+--+--+
| 1| 3|
| 1| 4|
| 2| 3|
| 2| 4|
+--+--+

Related Statements