[CALCITE-3182] Trim unused fields for plan of materialized-view before matching.

[jinxing64]

What changes were proposed in this pull request?

In current code, before matching query with materialized-view, unused fields of query is trimmed but materialized-view is not. Thus below simple SQL fails to be matched though query and materialized-
view are exactly the same:

@Test public void testMaterializationAfterTrimingOfUnusedFields() {
  String sql =
    "select \"y\".\"deptno\", \"y\".\"name\", \"x\".\"sum_salary\"\n" +
    "from\n" +
    " (select \"deptno\", sum(\"salary\") \"sum_salary\" from \"emps\" group by \"deptno\") \"x\"\n" +
    " join\n" +
    " \"depts\" \"y\"\n" +
    " on \"x\".\"deptno\"=\"y\".\"deptno\"\n";
    checkMaterialize(sql, sql);
}

Checking CalciteMaterializer https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/prepare/CalciteMaterializer.java#L83 , I think the code intends to do the trimming, but didn't call the method.
Since unused fields of query is trimmed anyway https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/prepare/CalcitePrepareImpl.java#L995 , thus I think there's no necessity to keep the materialized-view un-trimmed

How was this patch tested?

Added new test.

[jinxing64]

@DonnyZone
Thanks a lot for pointing me to https://issues.apache.org/jira/browse/CALCITE-3113 . As the comment I left in CALCITE-3113, my idea is that row-type checking in https://github.com/apache/calcite/blob/master/core/src/main/java/org/apache/calcite/plan/SubstitutionVisitor.java#L498 is too strict, I think we might just need to assure that the final result from SubstitutionVisitor should have same row-type as before. That's enough.
How do you think ?

[jinxing64]

As CALCITE-3113 is already resolved by
0a87daf
I will continue working on this PR.
@rubenada @DonnyZone
I updated this PR and tests passed. Please take another look when you have time

[rubenada]

LGTM

[jinxing64]

@rubenada
THX for approving !

[DonnyZone]

+1

[jinxing64]

THX @DonnyZone

[rubenada]

@jinxing64 could you please update the commit message and add your "name in parentheses at the end of the message" (as described in the contributing guidelines)

[jinxing64]

@rubenada
THX ~ I updated the commit message and sent a email to dev-subscribe@calcite.apache.org for mailing list subscription

[jinxing64]

@rubenada
THX for merging !