GitHub user dongjoon-hyun opened a pull request:
https://github.com/apache/spark/pull/12312
[SPARK-14545][SQL] Improve `LikeSimplification` by adding `a%b` rule
## What changes were proposed in this pull request?
Current `LikeSimplification` handles the following four rules.
- 'a%' => expr.StartsWith("a")
- '%b' => expr.EndsWith("b")
- '%a%' => expr.Contains("a")
- 'a' => EqualTo("a")
This PR adds the following rule.
- 'a%b' => expr.Length() > 2 && expr.StartsWith("a") && expr.EndsWith("b")
Here, 2 is statically calculated from "a".size + "b".size.
**Before**
```
scala> sql("select a from (select explode(array('abc','adc')) a) T where a
like 'a%c'").explain()
== Physical Plan ==
WholeStageCodegen
: +- Filter a#5 LIKE a%c
: +- INPUT
+- Generate explode([abc,adc]), false, false, [a#5]
+- Scan OneRowRelation[]
```
**After**
```
scala> sql("select a from (select explode(array('abc','adc')) a) T where a
like 'a%c'").explain()
== Physical Plan ==
WholeStageCodegen
: +- Filter ((length(a#5) >= 2) && (StartsWith(a#5, a) && EndsWith(a#5,
c)))
: +- INPUT
+- Generate explode([abc,adc]), false, false, [a#5]
+- Scan OneRowRelation[]
```
## How was this patch tested?
Pass the Jenkins tests (including new testcase).
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/dongjoon-hyun/spark SPARK-14545
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/12312.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #12312
----
commit 8d496f63dd3e760a6c165738152afe44a5203fda
Author: Dongjoon Hyun <dongj...@apache.org>
Date: 2016-04-12T00:01:19Z
[SPARK-14545][SQL] Improve `LikeSimplification` by adding `a%b` rule
----
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