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Yuming Wang 9549a28149 [SPARK-24549][SQL] Support Decimal type push down to the parquet data sources 
## What changes were proposed in this pull request?

Support Decimal type push down to the parquet data sources.
The Decimal comparator used is: [`BINARY_AS_SIGNED_INTEGER_COMPARATOR`](c6764c4a08/parquet-column/src/main/java/org/apache/parquet/schema/PrimitiveComparator.java (L224-L292)).

## How was this patch tested?

unit tests and manual tests.

**manual tests**:
```scala
spark.range(10000000).selectExpr("id", "cast(id as decimal(9)) as d1", "cast(id as decimal(9, 2)) as d2", "cast(id as decimal(18)) as d3", "cast(id as decimal(18, 4)) as d4", "cast(id as decimal(38)) as d5", "cast(id as decimal(38, 18)) as d6").coalesce(1).write.option("parquet.block.size", 1048576).parquet("/tmp/spark/parquet/decimal")
val df = spark.read.parquet("/tmp/spark/parquet/decimal/")
spark.sql("set spark.sql.parquet.filterPushdown.decimal=true")
// Only read about 1 MB data
df.filter("d2 = 10000").show
// Only read about 1 MB data
df.filter("d4 = 10000").show
spark.sql("set spark.sql.parquet.filterPushdown.decimal=false")
// Read 174.3 MB data
df.filter("d2 = 10000").show
// Read 174.3 MB data
df.filter("d4 = 10000").show
```

Author: Yuming Wang <yumwang@ebay.com>

Closes #21556 from wangyum/SPARK-24549.
2018-07-16 15:44:51 +08:00
..
catalyst [SPARK-24549][SQL] Support Decimal type push down to the parquet data sources 2018-07-16 15:44:51 +08:00
core [SPARK-24549][SQL] Support Decimal type push down to the parquet data sources 2018-07-16 15:44:51 +08:00
hive [SPARK-24813][TESTS][HIVE][HOTFIX] HiveExternalCatalogVersionsSuite still flaky; fall back to Apache archive 2018-07-16 09:29:51 +08:00
hive-thriftserver [SPARK-24553][WEB-UI] http 302 fixes for href redirect 2018-06-27 15:36:59 -07:00
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.