wangyum opened a new pull request, #37519:
URL: https://github.com/apache/spark/pull/37519
### What changes were proposed in this pull request?
This PR moves `EliminateSorts` before `LimitPushDown`.
### Why are the changes needed?
Eliminate more sorts to improve query performance. For example:
```sql
SELECT *
FROM (SELECT *
FROM testdata
ORDER BY key) t1
CROSS JOIN (SELECT *
FROM testdata2
ORDER BY a) t2
LIMIT 2
```
Before this PR:
```
== Optimized Logical Plan ==
GlobalLimit 2
+- LocalLimit 2
+- Join Cross
:- LocalLimit 2
: +- Sort [key#13 ASC NULLS FIRST], true
: +- SerializeFromObject [TestData]
: +- ExternalRDD [obj#12]
+- LocalLimit 2
+- Sort [a#23 ASC NULLS FIRST], true
+- SerializeFromObject [TestData2]
+- ExternalRDD [obj#22]
```
After this PR:
```
== Optimized Logical Plan ==
GlobalLimit 2
+- LocalLimit 2
+- Join Cross
:- LocalLimit 2
: +- SerializeFromObject [TestData]
: +- ExternalRDD [obj#12]
+- LocalLimit 2
+- SerializeFromObject [TestData2]
+- ExternalRDD [obj#22]
```
### Does this PR introduce _any_ user-facing change?
No.
### How was this patch tested?
Unit test.
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