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Wenchen Fan 3c8b3609a1 [SPARK-30620][SQL] avoid unnecessary serialization in AggregateExpression 
### What changes were proposed in this pull request?

Expressions are very likely to be serialized and sent to executors, we should avoid unnecessary serialization overhead as much as we can.

This PR fixes `AggregateExpression`.

### Why are the changes needed?

small improvement

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

no

### How was this patch tested?

existing tests

Closes #27342 from cloud-fan/fix.

Authored-by: Wenchen Fan <wenchen@databricks.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
2020-01-24 01:15:57 +08:00
..
catalyst [SPARK-30620][SQL] avoid unnecessary serialization in AggregateExpression 2020-01-24 01:15:57 +08:00
core [SPARK-30188][SQL][TESTS][FOLLOW-UP] Remove sorted in asserts of comparing two strings 2020-01-23 23:01:25 +08:00
hive [SPARK-30535][SQL] Revert "[] Migrate ALTER TABLE commands to the new framework 2020-01-22 22:43:46 -08:00
hive-thriftserver [SPARK-30252][SQL] Disallow negative scale of Decimal 2020-01-21 21:09:48 +08:00
create-docs.sh [MINOR][DOCS] Minor doc fixes related with doc build and uses script dir in SQL doc gen script 2017-08-26 13:56:24 +09:00
gen-sql-markdown.py [SPARK-27328][SQL] Add 'deprecated' in ExpressionDescription for extended usage and SQL doc 2019-04-09 13:49:42 +08:00
mkdocs.yml [SPARK-21485][SQL][DOCS] Spark SQL documentation generation for built-in functions 2017-07-26 09:38:51 -07:00
README.md [SPARK-28980][CORE][SQL][STREAMING][MLLIB] Remove most items deprecated in Spark 2.2.0 or earlier, for Spark 3 2019-09-09 10:19:40 -05:00

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.