e1a172c201
## What changes were proposed in this pull request? Adds method `summary` that allows user to specify which statistics and percentiles to calculate. By default it include the existing statistics from `describe` and quartiles (25th, 50th, and 75th percentiles) similar to Pandas. Also changes the implementation of `describe` to delegate to `summary`. ## How was this patch tested? additional unit test Author: Andrew Ray <ray.andrew@gmail.com> Closes #18307 from aray/SPARK-21100. |
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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.