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Ali Afroozeh 0a6043f683 [SPARK-32755][SQL] Maintain the order of expressions in AttributeSet and ExpressionSet 
### What changes were proposed in this pull request?
This PR changes `AttributeSet` and `ExpressionSet` to maintain the insertion order of the elements. More specifically, we:
- change the underlying data structure of `AttributeSet` from `HashSet` to `LinkedHashSet` to maintain the insertion order.
- `ExpressionSet` already uses a list to keep track of the expressions, however, since it is extending Scala's immutable.Set class, operations such as map and flatMap are delegated to the immutable.Set itself. This means that the result of these operations is not an instance of ExpressionSet anymore, rather it's a implementation picked up by the parent class. We also remove this inheritance from `immutable.Set `and implement the needed methods directly. ExpressionSet has a very specific semantics and it does not make sense to extend `immutable.Set` anyway.
- change the `PlanStabilitySuite` to not sort the attributes, to be able to catch changes in the order of expressions in different runs.

### Why are the changes needed?
Expressions identity is based on the `ExprId` which is an auto-incremented number. This means that the same query can yield a query plan with different expression ids in different runs. `AttributeSet` and `ExpressionSet` internally use a `HashSet` as the underlying data structure, and therefore cannot guarantee the a fixed order of operations in different runs. This can be problematic in cases we like to check for plan changes in different runs.

### Does this PR introduce _any_ user-facing change?
No

### How was this patch tested?
Passes `PlanStabilitySuite` after regenerating the golden files.

Closes #29598 from dbaliafroozeh/FixOrderOfExpressions.

Authored-by: Ali Afroozeh <ali.afroozeh@databricks.com>
Signed-off-by: herman <herman@databricks.com>
2020-09-03 13:56:03 +02:00
..
catalyst [SPARK-32755][SQL] Maintain the order of expressions in AttributeSet and ExpressionSet 2020-09-03 13:56:03 +02:00
core [SPARK-32755][SQL] Maintain the order of expressions in AttributeSet and ExpressionSet 2020-09-03 13:56:03 +02:00
hive [SPARK-32400][SQL][TEST][FOLLOWUP][TEST-MAVEN] Fix resource loading error in HiveScripTransformationSuite 2020-09-02 18:27:29 +09:00
hive-thriftserver [SPARK-32772][SQL] Reduce log messages for spark-sql CLI 2020-09-02 13:31:06 -07:00
create-docs.sh [SPARK-31550][SQL][DOCS] Set nondeterministic configurations with general meanings in sql configuration doc 2020-04-27 17:08:52 +09:00
gen-sql-api-docs.py [SPARK-31474][SQL][FOLLOWUP] Replace _FUNC_ placeholder with functionname in the note field of expression info 2020-04-23 13:33:04 +09:00
gen-sql-config-docs.py [SPARK-31550][SQL][DOCS] Set nondeterministic configurations with general meanings in sql configuration doc 2020-04-27 17:08:52 +09:00
gen-sql-functions-docs.py [SPARK-31562][SQL] Update ExpressionDescription for substring, current_date, and current_timestamp 2020-04-26 11:46:52 -07:00
mkdocs.yml [SPARK-30731] Update deprecated Mkdocs option 2020-02-19 17:28:58 +09:00
README.md [SPARK-30510][SQL][DOCS] Publicly document Spark SQL configuration options 2020-02-09 19:20:47 +09:00

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 extensions that allow 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, and SQL configuration documentation that gets included as part of configuration.md in the main docs directory.