## 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).
Author: Dongjoon Hyun <dongjoon@apache.org>
Closes#12312 from dongjoon-hyun/SPARK-14545.
d7e124edfe