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Dilip Biswal 65a4bc143a [SPARK-21274][SQL] Implement INTERSECT ALL clause 
## What changes were proposed in this pull request?
Implements INTERSECT ALL clause through query rewrites using existing operators in Spark.  Please refer to [Link](https://drive.google.com/open?id=1nyW0T0b_ajUduQoPgZLAsyHK8s3_dko3ulQuxaLpUXE) for the design.

Input Query
``` SQL
SELECT c1 FROM ut1 INTERSECT ALL SELECT c1 FROM ut2
```
Rewritten Query
```SQL
   SELECT c1
    FROM (
         SELECT replicate_row(min_count, c1)
         FROM (
              SELECT c1,
                     IF (vcol1_cnt > vcol2_cnt, vcol2_cnt, vcol1_cnt) AS min_count
              FROM (
                   SELECT   c1, count(vcol1) as vcol1_cnt, count(vcol2) as vcol2_cnt
                   FROM (
                        SELECT c1, true as vcol1, null as vcol2 FROM ut1
                        UNION ALL
                        SELECT c1, null as vcol1, true as vcol2 FROM ut2
                        ) AS union_all
                   GROUP BY c1
                   HAVING vcol1_cnt >= 1 AND vcol2_cnt >= 1
                  )
              )
          )
```

## How was this patch tested?
Added test cases in SQLQueryTestSuite, DataFrameSuite, SetOperationSuite

Author: Dilip Biswal <dbiswal@us.ibm.com>

Closes #21886 from dilipbiswal/dkb_intersect_all_final.
2018-07-29 22:11:01 -07:00
..
catalyst [SPARK-21274][SQL] Implement INTERSECT ALL clause 2018-07-29 22:11:01 -07:00
core [SPARK-21274][SQL] Implement INTERSECT ALL clause 2018-07-29 22:11:01 -07:00
hive [SPARK-24865] Remove AnalysisBarrier 2018-07-27 14:29:05 +08:00
hive-thriftserver [SPARK-24829][STS] In Spark Thrift Server, CAST AS FLOAT inconsistent with spark-shell or spark-sql 2018-07-27 13:27:17 +08:00
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.