ODIn/spark-instrumented-optimizer
1
0
Fork 0
Code Issues Pull requests Projects Releases Wiki Activity
spark-instrumented-optimizer/sql
History
Tejas Patil 095862a3cf [SPARK-17271][SQL] Planner adds un-necessary Sort even if child ordering is semantically same as required ordering 
## What changes were proposed in this pull request?

Jira : https://issues.apache.org/jira/browse/SPARK-17271

Planner is adding un-needed SORT operation due to bug in the way comparison for `SortOrder` is done at https://github.com/apache/spark/blob/master/sql/core/src/main/scala/org/apache/spark/sql/execution/exchange/EnsureRequirements.scala#L253
`SortOrder` needs to be compared semantically because `Expression` within two `SortOrder` can be "semantically equal" but not literally equal objects.

eg. In case of `sql("SELECT * FROM table1 a JOIN table2 b ON a.col1=b.col1")`

Expression in required SortOrder:
```
      AttributeReference(
        name = "col1",
        dataType = LongType,
        nullable = false
      ) (exprId = exprId,
        qualifier = Some("a")
      )
```

Expression in child SortOrder:
```
      AttributeReference(
        name = "col1",
        dataType = LongType,
        nullable = false
      ) (exprId = exprId)
```

Notice that the output column has a qualifier but the child attribute does not but the inherent expression is the same and hence in this case we can say that the child satisfies the required sort order.

This PR includes following changes:
- Added a `semanticEquals` method to `SortOrder` so that it can compare underlying child expressions semantically (and not using default Object.equals)
- Fixed `EnsureRequirements` to use semantic comparison of SortOrder

## How was this patch tested?

- Added a test case to `PlannerSuite`. Ran rest tests in `PlannerSuite`

Author: Tejas Patil <tejasp@fb.com>

Closes #14841 from tejasapatil/SPARK-17271_sort_order_equals_bug.
2016-08-28 19:14:58 +02:00
..
catalyst [SPARK-17271][SQL] Planner adds un-necessary Sort even if child ordering is semantically same as required ordering 2016-08-28 19:14:58 +02:00
core [SPARK-17271][SQL] Planner adds un-necessary Sort even if child ordering is semantically same as required ordering 2016-08-28 19:14:58 +02:00
hive [SPARK-17246][SQL] Add BigDecimal literal 2016-08-26 13:29:22 -07:00
hive-thriftserver [SPARK-17190][SQL] Removal of HiveSharedState 2016-08-25 12:50:03 +08:00
README.md [SPARK-16557][SQL] Remove stale doc in sql/README.md 2016-07-14 19:24:42 -07:00

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 an extension of SQLContext called HiveContext that allows users to write queries using a subset of HiveQL and access data from a Hive Metastore using Hive SerDes. There are also wrappers that allows 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.