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Yuming Wang 7be8d8a164 [SPARK-35185][SQL] Improve Distinct statistics estimation 
### What changes were proposed in this pull request?

This PR improves `Distinct` statistics estimation by rewrite it to `Aggregate`.

### Why are the changes needed?

1. The current implementation will lack column statistics.
2. Some rules before the `ReplaceDistinctWithAggregate` may use it. For example: https://github.com/apache/spark/pull/31113/files#diff-11264d807efa58054cca2d220aae8fba644ee0f0f2a4722c46d52828394846efR1808

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

No.

### How was this patch tested?

Unit test.

Closes #32291 from wangyum/SPARK-35185.

Authored-by: Yuming Wang <yumwang@ebay.com>
Signed-off-by: Yuming Wang <yumwang@ebay.com>
2021-06-18 21:48:44 +08:00
..
catalyst [SPARK-35185][SQL] Improve Distinct statistics estimation 2021-06-18 21:48:44 +08:00
core [SPARK-35608][SQL] Support AQE optimizer side transformUpWithPruning 2021-06-18 20:31:11 +08:00
hive [SPARK-35798][SQL] Fix SparkPlan.sqlContext usage 2021-06-17 13:49:38 +00:00
hive-thriftserver [SPARK-35680][SQL] Add fields to YearMonthIntervalType 2021-06-15 23:08:12 +03:00
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.