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Wenchen Fan 9f6b3e65cc [SPARK-21238][SQL] allow nested SQL execution 
## What changes were proposed in this pull request?

This is kind of another follow-up for https://github.com/apache/spark/pull/18064 .

In #18064 , we wrap every SQL command with SQL execution, which makes nested SQL execution very likely to happen. #18419 trid to improve it a little bit, by introduing `SQLExecition.ignoreNestedExecutionId`. However, this is not friendly to data source developers, they may need to update their code to use this `ignoreNestedExecutionId` API.

This PR proposes a new solution, to just allow nested execution. The downside is that, we may have multiple executions for one query. We can improve this by updating the data organization in SQLListener, to have 1-n mapping from query to execution, instead of 1-1 mapping. This can be done in a follow-up.

## How was this patch tested?

existing tests.

Author: Wenchen Fan <wenchen@databricks.com>

Closes #18450 from cloud-fan/execution-id.
2017-06-29 14:37:42 +08:00
..
catalyst [SPARK-21237][SQL] Invalidate stats once table data is changed 2017-06-29 11:32:29 +08:00
core [SPARK-21238][SQL] allow nested SQL execution 2017-06-29 14:37:42 +08:00
hive [SPARK-21237][SQL] Invalidate stats once table data is changed 2017-06-29 11:32:29 +08:00
hive-thriftserver [SPARK-20345][SQL] Fix STS error handling logic on HiveSQLException 2017-06-12 14:05:03 -07:00
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.