ODIn/spark-instrumented-optimizer
1
0
Fork 0
Code Issues Pull requests Projects Releases Wiki Activity
spark-instrumented-optimizer/sql
History
allisonwang-db 31bb9e04ad [SPARK-36063][SQL] Optimize OneRowRelation subqueries 
### What changes were proposed in this pull request?
This PR adds optimization for scalar and lateral subqueries with OneRowRelation as leaf nodes. It inlines such subqueries before decorrelation to avoid rewriting them as left outer joins. It also introduces a flag to turn on/off this optimization: `spark.sql.optimizer.optimizeOneRowRelationSubquery` (default: True).

For example:
```sql
select (select c1) from t
```
Analyzed plan:
```
Project [scalar-subquery#17 [c1#18] AS scalarsubquery(c1)#22]
:  +- Project [outer(c1#18)]
:     +- OneRowRelation
+- LocalRelation [c1#18, c2#19]
```

Optimized plan before this PR:
```
Project [c1#18#25 AS scalarsubquery(c1)#22]
+- Join LeftOuter, (c1#24 <=> c1#18)
   :- LocalRelation [c1#18]
   +- Aggregate [c1#18], [c1#18 AS c1#18#25, c1#18 AS c1#24]
      +- LocalRelation [c1#18]
```

Optimized plan after this PR:
```
LocalRelation [scalarsubquery(c1)#22]
```

### Why are the changes needed?
To optimize query plans.

### Does this PR introduce _any_ user-facing change?
No.

### How was this patch tested?
Added new unit tests.

Closes #33284 from allisonwang-db/spark-36063-optimize-subquery-one-row-relation.

Authored-by: allisonwang-db <allison.wang@databricks.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
(cherry picked from commit de8e4be92c)
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
2021-07-22 10:48:48 +08:00
..
catalyst [SPARK-36063][SQL] Optimize OneRowRelation subqueries 2021-07-22 10:48:48 +08:00
core [SPARK-36063][SQL] Optimize OneRowRelation subqueries 2021-07-22 10:48:48 +08:00
hive [SPARK-28266][SQL] convertToLogicalRelation should not interpret path property when reading Hive tables 2021-07-21 22:40:59 +08:00
hive-thriftserver [SPARK-36179][SQL] Support TimestampNTZType in SparkGetColumnsOperation 2021-07-20 09:49:25 +09:00
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
mkdocs.yml
README.md

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.