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Kent Yao b9cae37750 [SPARK-29774][SQL] Date and Timestamp type +/- null should be null as Postgres 
# What changes were proposed in this pull request?
Add an analyzer rule to convert unresolved `Add`, `Subtract`, etc. to `TimeAdd`, `DateAdd`, etc. according to the following policy:
```scala
 /**
   * For [[Add]]:
   * 1. if both side are interval, stays the same;
   * 2. else if one side is interval, turns it to [[TimeAdd]];
   * 3. else if one side is date, turns it to [[DateAdd]] ;
   * 4. else stays the same.
   *
   * For [[Subtract]]:
   * 1. if both side are interval, stays the same;
   * 2. else if the right side is an interval, turns it to [[TimeSub]];
   * 3. else if one side is timestamp, turns it to [[SubtractTimestamps]];
   * 4. else if the right side is date, turns it to [[DateDiff]]/[[SubtractDates]];
   * 5. else if the left side is date, turns it to [[DateSub]];
   * 6. else turns it to stays the same.
   *
   * For [[Multiply]]:
   * 1. If one side is interval, turns it to [[MultiplyInterval]];
   * 2. otherwise, stays the same.
   *
   * For [[Divide]]:
   * 1. If the left side is interval, turns it to [[DivideInterval]];
   * 2. otherwise, stays the same.
   */
```
Besides, we change datetime functions from implicit cast types to strict ones, all available type coercions happen in `DateTimeOperations` coercion rule.
### Why are the changes needed?

Feature Parity between PostgreSQL and Spark, and make the null semantic consistent with Spark.

### Does this PR introduce any user-facing change?

1. date_add/date_sub functions only accept int/tinynit/smallint as the second arg, double/string etc, are forbidden like hive, which produce weird results.

### How was this patch tested?

add ut

Closes #26412 from yaooqinn/SPARK-29774.

Authored-by: Kent Yao <yaooqinn@hotmail.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
2019-12-05 22:03:44 +08:00
..
catalyst [SPARK-29774][SQL] Date and Timestamp type +/- null should be null as Postgres 2019-12-05 22:03:44 +08:00
core [SPARK-29774][SQL] Date and Timestamp type +/- null should be null as Postgres 2019-12-05 22:03:44 +08:00
hive [SPARK-29425][SQL] The ownership of a database should be respected 2019-12-05 16:14:27 +08:00
hive-thriftserver [SPARK-28461][SQL] Pad Decimal numbers with trailing zeros to the scale of the column 2019-12-02 09:02:39 +09:00
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-27328][SQL] Add 'deprecated' in ExpressionDescription for extended usage and SQL doc 2019-04-09 13:49:42 +08:00
mkdocs.yml [SPARK-21485][SQL][DOCS] Spark SQL documentation generation for built-in functions 2017-07-26 09:38:51 -07:00
README.md [SPARK-28980][CORE][SQL][STREAMING][MLLIB] Remove most items deprecated in Spark 2.2.0 or earlier, for Spark 3 2019-09-09 10:19:40 -05:00

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.