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[SPARK-20366][SQL] Fix recursive join reordering: inside joins are not reordered

wangzhenhua authored 7 years ago

## What changes were proposed in this pull request?

If a plan has multi-level successive joins, e.g.:
```
         Join
         /   \
     Union   t5
      /   \
    Join  t4
    /   \
  Join  t3
  /  \
 t1   t2
```
Currently we fail to reorder the inside joins, i.e. t1, t2, t3.

In join reorder, we use `OrderedJoin` to indicate a join has been ordered, such that when transforming down the plan, these joins don't need to be rerodered again.

But there's a problem in the definition of `OrderedJoin`:
The real join node is a parameter, but not a child. This breaks the transform procedure because `mapChildren` applies transform function on parameters which should be children.

In this patch, we change `OrderedJoin` to a class having the same structure as a join node.

## How was this patch tested?

Add a corresponding test case.

Author: wangzhenhua <wangzhenhua@huawei.com>

Closes #17668 from wzhfy/recursiveReorder.

321b4f03

321b4f03 7 years ago

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Apache Spark

Spark is a fast and general cluster computing system for Big Data. It provides high-level APIs in Scala, Java, Python, and R, and an optimized engine that supports general computation graphs for data analysis. It also supports a rich set of higher-level tools including Spark SQL for SQL and DataFrames, MLlib for machine learning, GraphX for graph processing, and Spark Streaming for stream processing.

http://spark.apache.org/

Online Documentation

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Building Spark

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You can build Spark using more than one thread by using the -T option with Maven, see "Parallel builds in Maven 3". More detailed documentation is available from the project site, at "Building Spark".

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Interactive Scala Shell

The easiest way to start using Spark is through the Scala shell:

./bin/spark-shell

Try the following command, which should return 1000:

scala> sc.parallelize(1 to 1000).count()

Interactive Python Shell

Alternatively, if you prefer Python, you can use the Python shell:

./bin/pyspark

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>>> sc.parallelize(range(1000)).count()

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./bin/run-example SparkPi

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MASTER=spark://host:7077 ./bin/run-example SparkPi

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