spark-instrumented-optimizer/sql
Wenchen Fan b8d3da16b1 [SPARK-35874][SQL] AQE Shuffle should wait for its subqueries to finish before materializing
### What changes were proposed in this pull request?

Currently, AQE uses a very tricky way to trigger and wait for the subqueries:
1. submitting stage calls `QueryStageExec.materialize`
2. `QueryStageExec.materialize` calls `executeQuery`
3. `executeQuery` does some preparation works, which goes to `QueryStageExec.doPrepare`
4. `QueryStageExec.doPrepare` calls `prepare` of shuffle/broadcast, which triggers all the subqueries in this stage
5. `executeQuery` then calls `waitForSubqueries`, which does nothing because `QueryStageExec` itself has no subqueries
6. then we submit the shuffle/broadcast job, without waiting for subqueries
7. for `ShuffleExchangeExec.mapOutputStatisticsFuture`, it calls `child.execute`, which calls `executeQuery` and wait for subqueries in the query tree of `child`
8. The only missing case is: `ShuffleExchangeExec` itself may contain subqueries(repartition expression) and AQE doesn't wait for it.

A simple fix would be overwriting `waitForSubqueries` in `QueryStageExec`, and forward the request to shuffle/broadcast, but this PR proposes a different and probably cleaner way: we follow `execute`/`doExecute` in `SparkPlan`, and add similar APIs in the AQE version of "execute", which gets a future from shuffle/broadcast.

### Why are the changes needed?

bug fix

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

a query fails without the fix and can run now

### How was this patch tested?

new test

Closes #33058 from cloud-fan/aqe.

Authored-by: Wenchen Fan <wenchen@databricks.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
(cherry picked from commit 2df67a1a1b)
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
2021-07-09 00:21:08 +08:00
..
catalyst [SPARK-35958][CORE] Refactor SparkError.scala to SparkThrowable.java 2021-07-08 23:55:11 +08:00
core [SPARK-35874][SQL] AQE Shuffle should wait for its subqueries to finish before materializing 2021-07-09 00:21:08 +08:00
hive [SPARK-35686][SQL] Not allow using auto-generated alias when creating view 2021-07-01 12:47:38 +00:00
hive-thriftserver [SPARK-35958][CORE] Refactor SparkError.scala to SparkThrowable.java 2021-07-08 23:55:11 +08:00
create-docs.sh [SPARK-34010][SQL][DODCS] Use python3 instead of python in SQL documentation build 2021-01-05 19:48:10 +09:00
gen-sql-api-docs.py [SPARK-34747][SQL][DOCS] Add virtual operators to the built-in function document 2021-03-19 10:19:26 +09:00
gen-sql-config-docs.py [SPARK-32194][PYTHON] Use proper exception classes instead of plain Exception 2021-05-26 11:54:40 +09:00
gen-sql-functions-docs.py
mkdocs.yml
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.