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wangzhenhua 039ed9fe8a [SPARK-19271][SQL] Change non-cbo estimation of aggregate 
## What changes were proposed in this pull request?

Change non-cbo estimation behavior of aggregate:
- If groupExpression is empty, we can know row count (=1) and the corresponding size;
- otherwise, estimation falls back to UnaryNode's computeStats method, which should not propagate rowCount and attributeStats in Statistics because they are not estimated in that method.

## How was this patch tested?

Added test case

Author: wangzhenhua <wangzhenhua@huawei.com>

Closes #16631 from wzhfy/aggNoCbo.
2017-01-19 22:18:47 -08:00
..
catalyst [SPARK-19271][SQL] Change non-cbo estimation of aggregate 2017-01-19 22:18:47 -08:00
core [SPARK-19292][SQL] filter with partition columns should be case-insensitive on Hive tables 2017-01-19 20:09:48 -08:00
hive [SPARK-19292][SQL] filter with partition columns should be case-insensitive on Hive tables 2017-01-19 20:09:48 -08:00
hive-thriftserver [SPARK-18857][SQL] Don't use Iterator.duplicate for incrementalCollect in Thrift Server 2017-01-10 13:27:55 +00:00
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.