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Marco Gaido 891032da6f [SPARK-25691][SQL] Use semantic equality in AliasViewChild in order to compare attributes 
## What changes were proposed in this pull request?

When we compare attributes, in general, we should always refer to semantic equality, as the default `equal` method can return false when there are "cosmetic" differences between them, but still they are the same thing; at least we have to consider them so when analyzing/optimizing queries.

The PR focuses on the usage and comparison of the `output` of a `LogicalPlan`, which is a `Seq[Attribute]` in `AliasViewChild`. In this case, using equality implicitly fails to check the semantic equality. This results in the operator failing to stabilize.

## How was this patch tested?

running the tests with the patch provided by maryannxue in https://github.com/apache/spark/pull/22060

Closes #22713 from mgaido91/SPARK-25691.

Authored-by: Marco Gaido <marcogaido91@gmail.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
2018-10-31 09:18:53 +08:00
..
catalyst [SPARK-25691][SQL] Use semantic equality in AliasViewChild in order to compare attributes 2018-10-31 09:18:53 +08:00
core [SPARK-25848][SQL][TEST] Refactor CSVBenchmarks to use main method 2018-10-30 09:18:55 -07:00
hive [SPARK-25864][SQL][TEST] Make main args accessible for BenchmarkBase's subclass 2018-10-29 20:00:31 +08:00
hive-thriftserver [SPARK-25735][CORE][MINOR] Improve start-thriftserver.sh: print clean usage and exit with code 1 2018-10-17 09:56:17 -05:00
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.