[Enhancement] add unionToValues optimizer rule (backport #42915)

[mergify]

Why I'm doing:

For performing a UNION ALL with N SELECT constants, currently, N SELECT constants Fragments and one UNION ALL Fragment are generated. However, some user queries include UNION ALLs with several hundred or even thousands of constants, thus generating a massive amount of fragments and pipeline drivers, which significantly impacts performance.

eg:

select 1 union all select 10 + 'a' union all select 3

mysql> explain logical select 1 union all select 10 + 'a' union all select 3;
+-----------------------------------------------------------------------------------------+
| Explain String                                                                          |
+-----------------------------------------------------------------------------------------+
| - Output => [9:cast]                                                                    |
|     - UNION => [9: cast]                                                                |
|             Estimates: {row: 3, cpu: ?, memory: ?, network: ?, cost: 0.0}               |
|         - VALUES => [3:cast]                                                            |
|                 Estimates: {row: 1, cpu: 0.00, memory: 0.00, network: 0.00, cost: 0.00} |
|                 3:cast := 1.0                                                           |
|         - VALUES => [5:expr]                                                            |
|                 Estimates: {row: 1, cpu: ?, memory: ?, network: ?, cost: 0.0}           |
|                 5:expr := 10.0 + cast('a' as double)                                    |
|         - VALUES => [8:cast]                                                            |
|                 Estimates: {row: 1, cpu: 0.00, memory: 0.00, network: 0.00, cost: 0.00} |
|                 8:cast := 3.0                                                           |
+-----------------------------------------------------------------------------------------+
12 rows in set (0.01 sec)

manually changing it to use values greatly reduces the number of fragments:

mysql> explain logical select * from (values (1), (10 + 'a'), (3));
+---------------------------------------------------------------------------+
| Explain String                                                            |
+---------------------------------------------------------------------------+
| - Output => [1:column_0]                                                  |
|     - VALUES => {1.0}, {10.0 + cast('a' as double)}, {3.0}                |
|             Estimates: {row: 3, cpu: ?, memory: ?, network: ?, cost: 0.0} |
+---------------------------------------------------------------------------+
3 rows in set (0.04 sec)

What I'm doing:

For this scenario, add an optimization rule to transform all constant UNION ALLs into a single Values operator to avoid generating a massive number of fragments.

mysql> explain logical select 1 union all select 10 + 'a' union all select 3;
+---------------------------------------------------------------------------+
| Explain String                                                            |
+---------------------------------------------------------------------------+
| - Output => [9:cast]                                                      |
|     - VALUES => {1.0}, {10.0 + cast('a' as double)}, {3.0}                |
|             Estimates: {row: 3, cpu: ?, memory: ?, network: ?, cost: 0.0} |
+---------------------------------------------------------------------------+
3 rows in set (0.02 sec)

What type of PR is this:

• BugFix
• Feature
• Enhancement
• Refactor
• UT
• Doc
• Tool

Does this PR entail a change in behavior?

• Yes, this PR will result in a change in behavior.
• No, this PR will not result in a change in behavior.

If yes, please specify the type of change:

• Interface/UI changes: syntax, type conversion, expression evaluation, display information
• Parameter changes: default values, similar parameters but with different default values
• Policy changes: use new policy to replace old one, functionality automatically enabled
• Feature removed
• Miscellaneous: upgrade & downgrade compatibility, etc.

Checklist:

• I have added test cases for my bug fix or my new feature
• This pr needs user documentation (for new or modified features or behaviors)
• I have added documentation for my new feature or new function
• This is a backport pr

[mergify]

Cherry-pick of 52290a0 has failed:

On branch mergify/bp/branch-3.2/pr-42915
Your branch is up to date with 'origin/branch-3.2'.

You are currently cherry-picking commit 52290a02c7.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   fe/fe-core/src/main/java/com/starrocks/sql/optimizer/operator/logical/LogicalValuesOperator.java
	new file:   fe/fe-core/src/main/java/com/starrocks/sql/optimizer/rule/transformation/UnionToValuesRule.java
	modified:   fe/fe-core/src/test/java/com/starrocks/sql/plan/SelectConstTest.java
	modified:   fe/fe-core/src/test/java/com/starrocks/sql/plan/SetTest.java

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   fe/fe-core/src/main/java/com/starrocks/sql/optimizer/Optimizer.java
	both modified:   fe/fe-core/src/main/java/com/starrocks/sql/optimizer/rule/RuleType.java

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[mergify]

@mergify[bot]: Backport conflict, please reslove the conflict and resubmit the pr

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud