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Maxim Gekk 31c4fab3fb [SPARK-26081][SQL] Prevent empty files for empty partitions in Text datasources 
## What changes were proposed in this pull request?

In the PR, I propose to postpone creation of `OutputStream`/`Univocity`/`JacksonGenerator` till the first row should be written. This prevents creation of empty files for empty partitions. So, no need to open and to read such files back while loading data from the location.

## How was this patch tested?

Added tests for Text, JSON and CSV datasource where empty dataset is written but should not produce any files.

Closes #23052 from MaxGekk/text-empty-files.

Lead-authored-by: Maxim Gekk <max.gekk@gmail.com>
Co-authored-by: Maxim Gekk <maxim.gekk@databricks.com>
Signed-off-by: Sean Owen <sean.owen@databricks.com>
2018-11-29 10:31:31 -06:00
..
catalyst [SPARK-26211][SQL] Fix InSet for binary, and struct and array with null. 2018-11-29 22:37:02 +08:00
core [SPARK-26081][SQL] Prevent empty files for empty partitions in Text datasources 2018-11-29 10:31:31 -06:00
hive [SPARK-26134][CORE] Upgrading Hadoop to 2.7.4 to fix java.version problem 2018-11-21 23:09:57 -08:00
hive-thriftserver [SPARK-26090][CORE][SQL][ML] Resolve most miscellaneous deprecation and build warnings for Spark 3 2018-11-19 09:16:42 -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.