[SPARK-20356][SQL] Pruned InMemoryTableScanExec should have correct output partitioning and ordering

[viirya]

What changes were proposed in this pull request?

The output of InMemoryTableScanExec can be pruned and mismatch with InMemoryRelation and its child plan's output. This causes wrong output partitioning and ordering.

How was this patch tested?

Jenkins tests.

Please review http://spark.apache.org/contributing.html before opening a pull request.

[viirya]

cc @cloud-fan@hvanhovell@dilipbiswal

[SparkQA]

Test build #75927 has finished for PR 17679 at commit 17e1f9e.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #75926 has finished for PR 17679 at commit b6e42b5.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[dilipbiswal]

@viirya Thank you for a quick fix. The change looks good to me. I have a question. Before the fix, we changed the output partitioning of relation's child. But how come it was not reflected on the plan ? If it was reflected on the plan then we could quickly figure out whats wrong ? Here is the plan before this fix.

*HashAggregate(keys=[item#245], functions=[count(1)], output=[item#245, count#279L])
+- *HashAggregate(keys=[item#245], functions=[partial_count(1)], output=[item#245, count#295L])
+- InMemoryTableScan [item#245]
+- InMemoryRelation [id#237, item#245], true, 10000, StorageLevel(disk, memory, deserialized, 1 replicas)
+- *HashAggregate(keys=[id#237, item#245], functions=[], output=[id#237, item#245])
+- Exchange hashpartitioning(id#237, item#245, 200)
+- *HashAggregate(keys=[id#237, item#245], functions=[], output=[id#237, item#245])
+- *Project [id#237, group#227 AS item#245]
+- *BroadcastHashJoin [item#226], [item#236], Inner, BuildRight
:- *Project [_1#223 AS item#226, _2#224 AS group#227]
: +- *Filter isnotnull(_1#223)
: +- LocalTableScan [_1#223, _2#224]
+- BroadcastExchange HashedRelationBroadcastMode(List(input[0, string, true]))
+- *Project [_1#233 AS item#236, _2#234 AS id#237]
+- *Filter isnotnull(_1#233)
+- LocalTableScan [_1#233, _2#234]

Is there any indication on the plan that partitioning info got changed ? Just want to learn :-)

[viirya]

@dilipbiswal As outputPartitioning/Ordering is not one of arguments of query plan, it won't be shown in the string representation.

[dilipbiswal]

@viirya Ok.. thank you.

[viirya]

Btw, you can sense there might be a problem since the difference of output between InMemoryTableScan [item#245] and InMemoryRelation [id#237, item#245]...

[dilipbiswal]

@viirya Isn't that a normal thing simon due to column pruning ? Is that stuff tied to partitioning somehow ?

[viirya]

Oh, as the outputPartitioning/Ordering is strongly related to output, so when the output is changed, it quite indicates the partitioning/ordering can be wrong.

[dilipbiswal]

@viirya i see. Thanks :-)

[cloud-fan]

will we return invalid outputPartitioning? Think about a InMemoryTableScanExec that only read column a, and the outputPartitioning may be a, b, is that expected?

[viirya]

@cloud-fan I've raised similar question before in a PR. I remember I got an answer that an invalid outputPartitioning like this won't cause problem.

[viirya]

A similar example is ProjectExec which takes child.outputPartitioning as its outputPartitioning. But a projection can also change child's output like [a, b] -> [a].

[cloud-fan]

thanks, merging to master/2.2!

[viirya]

Thanks! @cloud-fan