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Kent Yao cdd8e51742 [SPARK-33419][SQL] Unexpected behavior when using SET commands before a query in SparkSession.sql 
### What changes were proposed in this pull request?

SparkSession.sql converts a string value to a DataFrame, and the string value should be one single SQL statement ending up w/ or w/o one or more semicolons. e.g.

```sql
scala> spark.sql(" select 2").show
+---+
|  2|
+---+
|  2|
+---+
scala> spark.sql(" select 2;").show
+---+
|  2|
+---+
|  2|
+---+

scala> spark.sql(" select 2;;;;").show
+---+
|  2|
+---+
|  2|
+---+
```
If we put 2 or more statements in, it fails in the parser as expected, e.g.

```sql
scala> spark.sql(" select 2; select 1;").show
org.apache.spark.sql.catalyst.parser.ParseException:
extraneous input 'select' expecting {<EOF>, ';'}(line 1, pos 11)

== SQL ==
 select 2; select 1;
-----------^^^

  at org.apache.spark.sql.catalyst.parser.ParseException.withCommand(ParseDriver.scala:263)
  at org.apache.spark.sql.catalyst.parser.AbstractSqlParser.parse(ParseDriver.scala:130)
  at org.apache.spark.sql.execution.SparkSqlParser.parse(SparkSqlParser.scala:51)
  at org.apache.spark.sql.catalyst.parser.AbstractSqlParser.parsePlan(ParseDriver.scala:81)
  at org.apache.spark.sql.SparkSession.$anonfun$sql$2(SparkSession.scala:610)
  at org.apache.spark.sql.catalyst.QueryPlanningTracker.measurePhase(QueryPlanningTracker.scala:111)
  at org.apache.spark.sql.SparkSession.$anonfun$sql$1(SparkSession.scala:610)
  at org.apache.spark.sql.SparkSession.withActive(SparkSession.scala:769)
  at org.apache.spark.sql.SparkSession.sql(SparkSession.scala:607)
  ... 47 elided
```

As a very generic user scenario, users may want to change some settings before they execute
the queries. They may pass a string value like `set spark.sql.abc=2; select 1;` into this API, which creates a confusing gap between the actual effect and the user's expectations.

The user may want the query to be executed with spark.sql.abc=2, but Spark actually treats the whole part of `2; select 1;` as the value of the property 'spark.sql.abc',
e.g.

```
scala> spark.sql("set spark.sql.abc=2; select 1;").show
+-------------+------------+
|          key|       value|
+-------------+------------+
|spark.sql.abc|2; select 1;|
+-------------+------------+
```

What's more, the SET symbol could digest everything behind it, which makes it unstable from version to version, e.g.

#### 3.1
```sql
scala> spark.sql("set;").show
org.apache.spark.sql.catalyst.parser.ParseException:
Expected format is 'SET', 'SET key', or 'SET key=value'. If you want to include special characters in key, please use quotes, e.g., SET `ke y`=value.(line 1, pos 0)

== SQL ==
set;
^^^

  at org.apache.spark.sql.execution.SparkSqlAstBuilder.$anonfun$visitSetConfiguration$1(SparkSqlParser.scala:83)
  at org.apache.spark.sql.catalyst.parser.ParserUtils$.withOrigin(ParserUtils.scala:113)
  at org.apache.spark.sql.execution.SparkSqlAstBuilder.visitSetConfiguration(SparkSqlParser.scala:72)
  at org.apache.spark.sql.execution.SparkSqlAstBuilder.visitSetConfiguration(SparkSqlParser.scala:58)
  at org.apache.spark.sql.catalyst.parser.SqlBaseParser$SetConfigurationContext.accept(SqlBaseParser.java:2161)
  at org.antlr.v4.runtime.tree.AbstractParseTreeVisitor.visit(AbstractParseTreeVisitor.java:18)
  at org.apache.spark.sql.catalyst.parser.AstBuilder.$anonfun$visitSingleStatement$1(AstBuilder.scala:77)
  at org.apache.spark.sql.catalyst.parser.ParserUtils$.withOrigin(ParserUtils.scala:113)
  at org.apache.spark.sql.catalyst.parser.AstBuilder.visitSingleStatement(AstBuilder.scala:77)
  at org.apache.spark.sql.catalyst.parser.AbstractSqlParser.$anonfun$parsePlan$1(ParseDriver.scala:82)
  at org.apache.spark.sql.catalyst.parser.AbstractSqlParser.parse(ParseDriver.scala:113)
  at org.apache.spark.sql.execution.SparkSqlParser.parse(SparkSqlParser.scala:51)
  at org.apache.spark.sql.catalyst.parser.AbstractSqlParser.parsePlan(ParseDriver.scala:81)
  at org.apache.spark.sql.SparkSession.$anonfun$sql$2(SparkSession.scala:610)
  at org.apache.spark.sql.catalyst.QueryPlanningTracker.measurePhase(QueryPlanningTracker.scala:111)
  at org.apache.spark.sql.SparkSession.$anonfun$sql$1(SparkSession.scala:610)
  at org.apache.spark.sql.SparkSession.withActive(SparkSession.scala:769)
  at org.apache.spark.sql.SparkSession.sql(SparkSession.scala:607)
  ... 47 elided

scala> spark.sql("set a;").show
org.apache.spark.sql.catalyst.parser.ParseException:
Expected format is 'SET', 'SET key', or 'SET key=value'. If you want to include special characters in key, please use quotes, e.g., SET `ke y`=value.(line 1, pos 0)

== SQL ==
set a;
^^^

  at org.apache.spark.sql.execution.SparkSqlAstBuilder.$anonfun$visitSetConfiguration$1(SparkSqlParser.scala:83)
  at org.apache.spark.sql.catalyst.parser.ParserUtils$.withOrigin(ParserUtils.scala:113)
  at org.apache.spark.sql.execution.SparkSqlAstBuilder.visitSetConfiguration(SparkSqlParser.scala:72)
  at org.apache.spark.sql.execution.SparkSqlAstBuilder.visitSetConfiguration(SparkSqlParser.scala:58)
  at org.apache.spark.sql.catalyst.parser.SqlBaseParser$SetConfigurationContext.accept(SqlBaseParser.java:2161)
  at org.antlr.v4.runtime.tree.AbstractParseTreeVisitor.visit(AbstractParseTreeVisitor.java:18)
  at org.apache.spark.sql.catalyst.parser.AstBuilder.$anonfun$visitSingleStatement$1(AstBuilder.scala:77)
  at org.apache.spark.sql.catalyst.parser.ParserUtils$.withOrigin(ParserUtils.scala:113)
  at org.apache.spark.sql.catalyst.parser.AstBuilder.visitSingleStatement(AstBuilder.scala:77)
  at org.apache.spark.sql.catalyst.parser.AbstractSqlParser.$anonfun$parsePlan$1(ParseDriver.scala:82)
  at org.apache.spark.sql.catalyst.parser.AbstractSqlParser.parse(ParseDriver.scala:113)
  at org.apache.spark.sql.execution.SparkSqlParser.parse(SparkSqlParser.scala:51)
  at org.apache.spark.sql.catalyst.parser.AbstractSqlParser.parsePlan(ParseDriver.scala:81)
  at org.apache.spark.sql.SparkSession.$anonfun$sql$2(SparkSession.scala:610)
  at org.apache.spark.sql.catalyst.QueryPlanningTracker.measurePhase(QueryPlanningTracker.scala:111)
  at org.apache.spark.sql.SparkSession.$anonfun$sql$1(SparkSession.scala:610)
  at org.apache.spark.sql.SparkSession.withActive(SparkSession.scala:769)
  at org.apache.spark.sql.SparkSession.sql(SparkSession.scala:607)
  ... 47 elided
```

#### 2.4

```sql
scala> spark.sql("set;").show
+---+-----------+
|key|      value|
+---+-----------+
|  ;|<undefined>|
+---+-----------+

scala> spark.sql("set a;").show
+---+-----------+
|key|      value|
+---+-----------+
| a;|<undefined>|
+---+-----------+
```

In this PR,
1.  make `set spark.sql.abc=2; select 1;` in `SparkSession.sql` fail directly, user should call `.sql` for each statement separately.
2. make the semicolon as the separator of statements, and if users want to use it as part of the property value, shall use quotes too.

### Why are the changes needed?

1. disambiguation for  `SparkSession.sql`
2. make semicolon work same both w/ `SET` and other statements

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

yes,
the semicolon works as a separator of statements now, it will be trimmed if it is at the end of the statement and fail the statement if it is in the middle. you need to use quotes if you want it to be part of the property value

### How was this patch tested?

new tests

Closes #30332 from yaooqinn/SPARK-33419.

Authored-by: Kent Yao <yaooqinn@hotmail.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
2020-11-13 06:58:16 +00:00
..
catalyst [SPARK-33419][SQL] Unexpected behavior when using SET commands before a query in SparkSession.sql 2020-11-13 06:58:16 +00:00
core [SPARK-33419][SQL] Unexpected behavior when using SET commands before a query in SparkSession.sql 2020-11-13 06:58:16 +00:00
hive [SPARK-33426][SQL][TESTS] Unify Hive SHOW TABLES tests 2020-11-13 05:15:13 +00:00
hive-thriftserver [SPARK-33352][CORE][SQL][SS][MLLIB][AVRO][K8S] Fix procedure-like declaration compilation warnings in Scala 2.13 2020-11-08 12:51:48 -06:00
create-docs.sh [SPARK-31550][SQL][DOCS] Set nondeterministic configurations with general meanings in sql configuration doc 2020-04-27 17:08:52 +09:00
gen-sql-api-docs.py [SPARK-31474][SQL][FOLLOWUP] Replace _FUNC_ placeholder with functionname in the note field of expression info 2020-04-23 13:33:04 +09:00
gen-sql-config-docs.py [SPARK-31550][SQL][DOCS] Set nondeterministic configurations with general meanings in sql configuration doc 2020-04-27 17:08:52 +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.