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Kousuke Saruta 880bbd6aaa [SPARK-35876][SQL] ArraysZip should retain field names to avoid being re-written by analyzer/optimizer 
### What changes were proposed in this pull request?

This PR fixes an issue that field names of structs generated by `arrays_zip` function could be unexpectedly re-written by analyzer/optimizer.
Here is an example.
```
val df = sc.parallelize(Seq((Array(1, 2), Array(3, 4)))).toDF("a1", "b1").selectExpr("arrays_zip(a1, b1) as zipped")
df.printSchema
root
 |-- zipped: array (nullable = true)
 |    |-- element: struct (containsNull = false)
 |    |    |-- a1: integer (nullable = true)                                      // OK. a1 is expected name
 |    |    |-- b1: integer (nullable = true)                                      // OK. b1 is expected name

df.explain
== Physical Plan ==
*(1) Project [arrays_zip(_1#3, _2#4) AS zipped#12]               // Not OK. field names are re-written as _1 and _2 respectively

df.write.parquet("/tmp/test.parquet")
val df2 = spark.read.parquet("/tmp/test.parquet")

df2.printSchema
root
 |-- zipped: array (nullable = true)
 |    |-- element: struct (containsNull = true)
 |    |    |-- _1: integer (nullable = true)                                      // Not OK. a1 is expected but got _1
 |    |    |-- _2: integer (nullable = true)                                      // Not OK. b1 is expected but got _2
```

This issue happens when aliases are eliminated by `AliasHelper.replaceAliasButKeepName` or `AliasHelper.trimNonTopLevelAliases` called via analyzer/optimizer
b89cd8d75a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala (L883)
b89cd8d75a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala (L3759)
I investigated functions which can be affected this issue but I found only `arrays_zip` so far.

To fix this issue, this PR changes the definition of `ArraysZip` to retain field names to avoid being re-written by analyzer/optimizer.

### Why are the changes needed?

This is apparently a bug.

### Does this PR introduce _any_ user-facing change?

No. After this change, the field names are no longer re-written but it should be expected behavior for users.

### How was this patch tested?

New tests.

Closes #33106 from sarutak/arrays-zip-retain-names.

Authored-by: Kousuke Saruta <sarutak@oss.nttdata.com>
Signed-off-by: Hyukjin Kwon <gurwls223@apache.org>
2021-06-29 12:28:41 +09:00
..
catalyst [SPARK-35876][SQL] ArraysZip should retain field names to avoid being re-written by analyzer/optimizer 2021-06-29 12:28:41 +09:00
core [SPARK-35876][SQL] ArraysZip should retain field names to avoid being re-written by analyzer/optimizer 2021-06-29 12:28:41 +09:00
hive [SPARK-35747][CORE] Avoid printing full Exception stack trace, if Hbase/Kafka/Hive services are not running in a secure cluster 2021-06-23 23:12:02 -07:00
hive-thriftserver [SPARK-35838][BUILD][TESTS] Ensure all modules can be maven test independently in Scala 2.13 2021-06-22 06:31:24 -07:00
create-docs.sh [SPARK-34010][SQL][DODCS] Use python3 instead of python in SQL documentation build 2021-01-05 19:48:10 +09:00
gen-sql-api-docs.py [SPARK-34747][SQL][DOCS] Add virtual operators to the built-in function document 2021-03-19 10:19:26 +09:00
gen-sql-config-docs.py [SPARK-32194][PYTHON] Use proper exception classes instead of plain Exception 2021-05-26 11:54:40 +09:00
gen-sql-functions-docs.py [SPARK-31562][SQL] Update ExpressionDescription for substring, current_date, and current_timestamp 2020-04-26 11:46:52 -07:00
mkdocs.yml [SPARK-30731] Update deprecated Mkdocs option 2020-02-19 17:28:58 +09:00
README.md [SPARK-30510][SQL][DOCS] Publicly document Spark SQL configuration options 2020-02-09 19:20:47 +09:00

README.md

Spark SQL

This module provides support for executing relational queries expressed in either SQL or the DataFrame/Dataset API.

Spark SQL is broken up into four subprojects:

  • Catalyst (sql/catalyst) - An implementation-agnostic framework for manipulating trees of relational operators and expressions.
  • Execution (sql/core) - A query planner / execution engine for translating Catalyst's logical query plans into Spark RDDs. This component also includes a new public interface, SQLContext, that allows users to execute SQL or LINQ statements against existing RDDs and Parquet files.
  • Hive Support (sql/hive) - Includes extensions that allow users to write queries using a subset of HiveQL and access data from a Hive Metastore using Hive SerDes. There are also wrappers that allow users to run queries that include Hive UDFs, UDAFs, and UDTFs.
  • HiveServer and CLI support (sql/hive-thriftserver) - Includes support for the SQL CLI (bin/spark-sql) and a HiveServer2 (for JDBC/ODBC) compatible server.

Running ./sql/create-docs.sh generates SQL documentation for built-in functions under sql/site, and SQL configuration documentation that gets included as part of configuration.md in the main docs directory.