spark-instrumented-optimizer/sql/core
Prakhar Jain f5e3302840 [SPARK-33399][SQL] Normalize output partitioning and sortorder with respect to aliases to avoid unneeded exchange/sort nodes
### What changes were proposed in this pull request?
This pull request tries to remove unneeded exchanges/sorts by normalizing the output partitioning and sortorder information correctly with respect to aliases.

Example: consider this join of three tables:

     |SELECT t2id, t3.id as t3id
     |FROM (
     |    SELECT t1.id as t1id, t2.id as t2id
     |    FROM t1, t2
     |    WHERE t1.id = t2.id
     |) t12, t3
     |WHERE t1id = t3.id

The plan for this looks like:

      *(9) Project [t2id#1034L, id#1004L AS t3id#1035L]
      +- *(9) SortMergeJoin [t1id#1033L], [id#1004L], Inner
         :- *(6) Sort [t1id#1033L ASC NULLS FIRST], false, 0
         :  +- Exchange hashpartitioning(t1id#1033L, 5), true, [id=#1343]   <------------------------------
         :     +- *(5) Project [id#996L AS t1id#1033L, id#1000L AS t2id#1034L]
         :        +- *(5) SortMergeJoin [id#996L], [id#1000L], Inner
         :           :- *(2) Sort [id#996L ASC NULLS FIRST], false, 0
         :           :  +- Exchange hashpartitioning(id#996L, 5), true, [id=#1329]
         :           :     +- *(1) Range (0, 10, step=1, splits=2)
         :           +- *(4) Sort [id#1000L ASC NULLS FIRST], false, 0
         :              +- Exchange hashpartitioning(id#1000L, 5), true, [id=#1335]
         :                 +- *(3) Range (0, 20, step=1, splits=2)
         +- *(8) Sort [id#1004L ASC NULLS FIRST], false, 0
            +- Exchange hashpartitioning(id#1004L, 5), true, [id=#1349]
               +- *(7) Range (0, 30, step=1, splits=2)

In this plan, the marked exchange could have been avoided as the data is already partitioned on "t1.id". This happens because AliasAwareOutputPartitioning class handles aliases only related to HashPartitioning. This change normalizes all output partitioning based on aliasing happening in Project.

### Why are the changes needed?
To remove unneeded exchanges.

### Does this PR introduce _any_ user-facing change?
No

### How was this patch tested?
New UT added.

On TPCDS 1000 scale, this change improves the performance of query 95 from 330 seconds to 170 seconds by removing the extra Exchange.

Closes #30300 from prakharjain09/SPARK-33399-outputpartitioning.

Authored-by: Prakhar Jain <prakharjain09@gmail.com>
Signed-off-by: Takeshi Yamamuro <yamamuro@apache.org>
2020-11-17 10:35:43 +09:00
..
benchmarks [SPARK-33455][SQL][TEST] Add SubExprEliminationBenchmark for benchmarking subexpression elimination 2020-11-14 19:02:36 -08:00
src [SPARK-33399][SQL] Normalize output partitioning and sortorder with respect to aliases to avoid unneeded exchange/sort nodes 2020-11-17 10:35:43 +09:00
pom.xml [SPARK-33107][BUILD][FOLLOW-UP] Remove com.twitter:parquet-hadoop-bundle:1.6.0 and orc.classifier 2020-10-11 21:54:56 -07:00