548b7db345
### What changes were proposed in this pull request? `HashRelation` has two separate code paths for unique key look up and non-unique key look up E.g. in its subclass [`UnsafeHashedRelation`](https://github.com/apache/spark/blob/master/sql/core/src/main/scala/org/apache/spark/sql/execution/joins/HashedRelation.scala#L144-L177), unique key look up is more efficient as it does not have e.g. extra `Iterator[UnsafeRow].hasNext()/next()` overhead per row. `BroadcastHashJoinExec` has handled unique key vs non-unique key separately in [code-gen path](https://github.com/apache/spark/blob/master/sql/core/src/main/scala/org/apache/spark/sql/execution/joins/BroadcastHashJoinExec.scala#L289-L321). But the non-codegen path for broadcast hash join and shuffled hash join do not separate it yet, so adding the support here. ### Why are the changes needed? Shuffled hash join and non-codegen broadcast hash join still rely on this code path for execution. So this PR will help save CPU for executing this two type of join. Adding codegen for shuffled hash join would be a different topic and I will add it in https://issues.apache.org/jira/browse/SPARK-32421 . Ran the same query as [`JoinBenchmark`](https://github.com/apache/spark/blob/master/sql/core/src/test/scala/org/apache/spark/sql/execution/benchmark/JoinBenchmark.scala#L153-L167), with enabling and disabling this feature. Verified 20% wall clock time improvement (switch control and test group order as well to verify the improvement to not be the noise). ``` Running benchmark: shuffle hash join Running case: shuffle hash join unique key SHJ off Stopped after 5 iterations, 4039 ms Running case: shuffle hash join unique key SHJ on Stopped after 5 iterations, 2898 ms Java HotSpot(TM) 64-Bit Server VM 1.8.0_181-b13 on Mac OS X 10.15.4 Intel(R) Core(TM) i9-9980HK CPU 2.40GHz shuffle hash join: Best Time(ms) Avg Time(ms) Stdev(ms) Rate(M/s) Per Row(ns) Relative ------------------------------------------------------------------------------------------------------------------------ shuffle hash join unique key SHJ off 707 808 81 5.9 168.6 1.0X shuffle hash join unique key SHJ on 547 580 50 7.7 130.4 1.3X ``` ``` Running benchmark: shuffle hash join Running case: shuffle hash join unique key SHJ on Stopped after 5 iterations, 3333 ms Running case: shuffle hash join unique key SHJ off Stopped after 5 iterations, 4268 ms Java HotSpot(TM) 64-Bit Server VM 1.8.0_181-b13 on Mac OS X 10.15.4 Intel(R) Core(TM) i9-9980HK CPU 2.40GHz shuffle hash join: Best Time(ms) Avg Time(ms) Stdev(ms) Rate(M/s) Per Row(ns) Relative ------------------------------------------------------------------------------------------------------------------------ shuffle hash join unique key SHJ on 565 667 60 7.4 134.8 1.0X shuffle hash join unique key SHJ off 774 854 85 5.4 184.4 0.7X ``` ### Does this PR introduce _any_ user-facing change? No. ### How was this patch tested? * Added test in `OuterJoinSuite` to cover left outer and right outer join. * Added test in `ExistenceJoinSuite` to cover left semi join, and existence join. * [Existing `joinSuite` already covered inner join.](https://github.com/apache/spark/blob/master/sql/core/src/test/scala/org/apache/spark/sql/JoinSuite.scala#L182) * [Existing `ExistenceJoinSuite` already covered left anti join, and existence join.](https://github.com/apache/spark/blob/master/sql/core/src/test/scala/org/apache/spark/sql/execution/joins/ExistenceJoinSuite.scala#L228) Closes #29216 from c21/unique-key. Authored-by: Cheng Su <chengsu@fb.com> Signed-off-by: Wenchen Fan <wenchen@databricks.com> |
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| .. | ||
| catalyst | ||
| core | ||
| hive | ||
| hive-thriftserver | ||
| create-docs.sh | ||
| gen-sql-api-docs.py | ||
| gen-sql-config-docs.py | ||
| gen-sql-functions-docs.py | ||
| mkdocs.yml | ||
| 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.