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Wenchen Fan 3d7f201f2a [SPARK-20229][SQL] add semanticHash to QueryPlan 
## What changes were proposed in this pull request?

Like `Expression`, `QueryPlan` should also have a `semanticHash` method, then we can put plans to a hash map and look it up fast. This PR refactors `QueryPlan` to follow `Expression` and put all the normalization logic in `QueryPlan.canonicalized`, so that it's very natural to implement `semanticHash`.

follow-up: improve `CacheManager` to leverage this `semanticHash` and speed up plan lookup, instead of iterating all cached plans.

## How was this patch tested?

existing tests. Note that we don't need to test the `semanticHash` method, once the existing tests prove `sameResult` is correct, we are good.

Author: Wenchen Fan <wenchen@databricks.com>

Closes #17541 from cloud-fan/plan-semantic.
2017-04-10 13:36:08 +08:00
..
catalyst [SPARK-20229][SQL] add semanticHash to QueryPlan 2017-04-10 13:36:08 +08:00
core [SPARK-20229][SQL] add semanticHash to QueryPlan 2017-04-10 13:36:08 +08:00
hive [SPARK-20229][SQL] add semanticHash to QueryPlan 2017-04-10 13:36:08 +08:00
hive-thriftserver [SPARK-20173][SQL][HIVE-THRIFTSERVER] Throw NullPointerException when HiveThriftServer2 is shutdown 2017-04-02 15:39:51 +01:00
README.md [SPARK-16557][SQL] Remove stale doc in sql/README.md 2016-07-14 19:24:42 -07:00

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 allows 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.