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HyukjinKwon 9618806f44 [SPARK-30847][SQL] Take productPrefix into account in MurmurHash3.productHash 
### What changes were proposed in this pull request?

This PR proposes to port Scala's bugfix https://github.com/scala/scala/pull/7693 (Scala 2.13) to address https://github.com/scala/bug/issues/10495 issue.

In short, it is possible for different product instances having the same children to have the same hash. See:

```scala
scala> spark.range(1).selectExpr("id - 1").queryExecution.analyzed.semanticHash()
res0: Int = -565572825

scala> spark.range(1).selectExpr("id + 1").queryExecution.analyzed.semanticHash()
res1: Int = -565572825
```

### Why are the changes needed?

It was found during the review of https://github.com/apache/spark/pull/27565. We should better produce different hash for different objects.

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

No, it's not identified. Possibly performance related issue.

### How was this patch tested?

Manually tested, and unittest was added.

Closes #27601 from HyukjinKwon/SPARK-30847.

Authored-by: HyukjinKwon <gurwls223@apache.org>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
2020-02-18 14:28:44 +08:00
..
catalyst [SPARK-30847][SQL] Take productPrefix into account in MurmurHash3.productHash 2020-02-18 14:28:44 +08:00
core [SPARK-30814][SQL] ALTER TABLE ... ADD COLUMN position should be able to reference columns being added 2020-02-18 13:01:45 +08:00
hive [SPARK-30808][SQL] Enable Java 8 time API in Thrift server 2020-02-18 02:15:44 +08:00
hive-thriftserver [SPARK-30808][SQL] Enable Java 8 time API in Thrift server 2020-02-18 02:15:44 +08:00
create-docs.sh [SPARK-30510][SQL][DOCS] Publicly document Spark SQL configuration options 2020-02-09 19:20:47 +09:00
gen-sql-api-docs.py [SPARK-30510][SQL][DOCS] Publicly document Spark SQL configuration options 2020-02-09 19:20:47 +09:00
gen-sql-config-docs.py [SPARK-30510][SQL][DOCS] Publicly document Spark SQL configuration options 2020-02-09 19:20:47 +09:00
mkdocs.yml [SPARK-30832][DOCS] SQL function doc headers should link to anchors 2020-02-17 19:19:28 -06:00
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.