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Wenchen Fan 8656af98c0 [SPARK-26861][SQL] deprecate typed sum/count/average 
## What changes were proposed in this pull request?

These builtin typed aggregate functions are not very useful:
1. users can just call the untyped ones and turn the resulting dataframe to a dataset. It has better performance.
2. the typed aggregate functions have subtle different behaviors regarding empty input.

I think we should get rid of these builtin typed agg functions and suggest users to use the untyped ones.

However, these functions are still useful as a demo of the `Aggregator` API, so I copied them to the example module.

## How was this patch tested?

N/A

Closes #23763 from cloud-fan/example.

Authored-by: Wenchen Fan <wenchen@databricks.com>
Signed-off-by: gatorsmile <gatorsmile@gmail.com>
2019-02-14 16:54:39 -08:00
..
catalyst [SPARK-26798][SQL] HandleNullInputsForUDF should trust nullability 2019-02-14 00:22:11 +09:00
core [SPARK-26861][SQL] deprecate typed sum/count/average 2019-02-14 16:54:39 -08:00
hive [SPARK-26794][SQL] SparkSession enableHiveSupport does not point to hive but in-memory while the SparkContext exists 2019-02-14 15:07:22 +08:00
hive-thriftserver [SPARK-26817][CORE] Use System.nanoTime to measure time intervals 2019-02-13 13:12:16 -06:00
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-21485][FOLLOWUP][SQL][DOCS] Describes examples and arguments separately, and note/since in SQL built-in function documentation 2017-08-05 10:10:56 -07:00
mkdocs.yml [SPARK-21485][SQL][DOCS] Spark SQL documentation generation for built-in functions 2017-07-26 09:38:51 -07:00
README.md [MINOR][DOC] Fix some typos and grammar issues 2018-04-06 13:37:08 +08:00

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 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.