AngersZhuuuu commented on a change in pull request #31010: URL: https://github.com/apache/spark/pull/31010#discussion_r606317946
########## File path: docs/sql-ref-syntax-qry-select-transform.md ########## @@ -0,0 +1,297 @@ +--- +layout: global +title: TRANSFORM +displayTitle: TRANSFORM +license: | + 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 + +The `TRANSFORM` clause is used to specifies a Hive-style transform (SELECT TRANSFORM/MAP/REDUCE) +query specification to transform the input by forking and running the specified script. Users can Review comment: Done ########## File path: docs/sql-ref-syntax-qry-select-transform.md ########## @@ -0,0 +1,297 @@ +--- +layout: global +title: TRANSFORM +displayTitle: TRANSFORM +license: | + 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 + +The `TRANSFORM` clause is used to specifies a Hive-style transform (SELECT TRANSFORM/MAP/REDUCE) +query specification to transform the input by forking and running the specified script. Users can +plug in their own custom mappers and reducers in the data stream by using features natively supported +in the Spark/Hive language. e.g. in order to run a custom mapper script `map_script` and a custom Review comment: Updated ########## File path: docs/sql-ref-syntax-qry-select-transform.md ########## @@ -0,0 +1,297 @@ +--- +layout: global +title: TRANSFORM +displayTitle: TRANSFORM +license: | + 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 + +The `TRANSFORM` clause is used to specifies a Hive-style transform (SELECT TRANSFORM/MAP/REDUCE) +query specification to transform the input by forking and running the specified script. Users can +plug in their own custom mappers and reducers in the data stream by using features natively supported +in the Spark/Hive language. e.g. in order to run a custom mapper script `map_script` and a custom +reducer script `reduce_script` the user can issue the following command which uses the TRANSFORM +clause to embed the mapper and the reducer scripts. + +Currently, Spark's script transform support two mode: + + 1. Without Hive: It means spark run Spark SQL without Hive support, in this mode, spark can use default + `ROW FORMAT DELIMITED` by treating data as STRING. + 2. WIth Hive: It means spark run Spark SQL with Hive support, in this mode, when spark use default format, + it will be treated as Hive default fomat. And spark can use Hive supported SerDe to process data. + +In both modes with default format, columns will be transformed to STRING and delimited by tabs before feeding +to the user script, Similarly, all `NULL` values will be converted to the literal string `\N` in order to +differentiate `NULL` values from empty strings. The standard output of the user script will be treated as +TAB-separated STRING columns, any cell containing only `\N` will be re-interpreted as a `NULL`, and then the +resulting STRING column will be cast to the data type specified in the table declaration in the usual way. +User scripts can output debug information to standard error which will be shown on the task detail page on hadoop. +These defaults can be overridden with `ROW FORMAT DELIMITED`. + +### Syntax + +```sql +rowFormat + : ROW FORMAT SERDE serde_class [ WITH SERDEPROPERTIES serde_props ] + | ROW FORMAT DELIMITED + [ FIELDS TERMINATED BY fields_terminated_char [ ESCAPED BY escapedBy ] ] + [ COLLECTION ITEMS TERMINATED BY collectionItemsTerminatedBy ] + [ MAP KEYS TERMINATED BY keysTerminatedBy ] + [ LINES TERMINATED BY linesSeparatedBy ] + [ NULL DEFINED AS nullDefinedAs ] + +inRowFormat=rowFormat +outRowFormat=rowFormat +namedExpressionSeq = named_expression [ , ... ] + +transformClause: Review comment: Done ########## File path: docs/sql-ref-syntax-qry-select-transform.md ########## @@ -0,0 +1,297 @@ +--- +layout: global +title: TRANSFORM +displayTitle: TRANSFORM +license: | + 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 + +The `TRANSFORM` clause is used to specifies a Hive-style transform (SELECT TRANSFORM/MAP/REDUCE) +query specification to transform the input by forking and running the specified script. Users can +plug in their own custom mappers and reducers in the data stream by using features natively supported +in the Spark/Hive language. e.g. in order to run a custom mapper script `map_script` and a custom +reducer script `reduce_script` the user can issue the following command which uses the TRANSFORM +clause to embed the mapper and the reducer scripts. + +Currently, Spark's script transform support two mode: + + 1. Without Hive: It means spark run Spark SQL without Hive support, in this mode, spark can use default + `ROW FORMAT DELIMITED` by treating data as STRING. + 2. WIth Hive: It means spark run Spark SQL with Hive support, in this mode, when spark use default format, + it will be treated as Hive default fomat. And spark can use Hive supported SerDe to process data. + +In both modes with default format, columns will be transformed to STRING and delimited by tabs before feeding +to the user script, Similarly, all `NULL` values will be converted to the literal string `\N` in order to +differentiate `NULL` values from empty strings. The standard output of the user script will be treated as +TAB-separated STRING columns, any cell containing only `\N` will be re-interpreted as a `NULL`, and then the +resulting STRING column will be cast to the data type specified in the table declaration in the usual way. +User scripts can output debug information to standard error which will be shown on the task detail page on hadoop. +These defaults can be overridden with `ROW FORMAT DELIMITED`. + +### Syntax + +```sql +rowFormat + : ROW FORMAT SERDE serde_class [ WITH SERDEPROPERTIES serde_props ] + | ROW FORMAT DELIMITED + [ FIELDS TERMINATED BY fields_terminated_char [ ESCAPED BY escapedBy ] ] + [ COLLECTION ITEMS TERMINATED BY collectionItemsTerminatedBy ] + [ MAP KEYS TERMINATED BY keysTerminatedBy ] + [ LINES TERMINATED BY linesSeparatedBy ] + [ NULL DEFINED AS nullDefinedAs ] + +inRowFormat=rowFormat +outRowFormat=rowFormat +namedExpressionSeq = named_expression [ , ... ] + +transformClause: + SELECT [ TRANSFORM ( namedExpressionSeq ) | MAP namedExpressionSeq | REDUCE namedExpressionSeq ] Review comment: Done -- This is an automated message from the Apache Git Service. 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