[CALCITE-7471] Alias is not auto generated for MATCH_RECOGNIZE

[snuyanzin]

Jira Link

CALCITE-7471

in case of toggled identifierExpansion and missed alias for table there should be generated one.
However in case of MATCH_RECOGNIZE it is missed (the PR is going to fix it)
example of query

SELECT *
FROM emp
MATCH_RECOGNIZE (
  MEASURES
     FINAL COUNT(A.deptno) AS deptno
  PATTERN (A B)
  DEFINE
    A AS A.empno = 123
)

unparsed query (there is EXPR$0 in SELECT however it is not defined anywhere)

SELECT `EXPR$0`.`DEPTNO`
FROM `CATALOG`.`SALES`.`EMP` AS `EMP` MATCH_RECOGNIZE(
MEASURES FINAL COUNT(`A`.`DEPTNO`) AS `DEPTNO`
PATTERN (`A` `B`)
DEFINE `A` AS PREV(`A`.`EMPNO`, 0) = 123)

[snuyanzin]

it is initialized at

calcite/core/src/main/java/org/apache/calcite/sql/validate/SqlValidatorImpl.java

Lines 2539 to 2540 in 37448dc

	// Add an alias if necessary.
	SqlNode newNode = node;

and

calcite/core/src/main/java/org/apache/calcite/sql/validate/SqlValidatorImpl.java

Lines 2568 to 2574 in 37448dc

	alias = SqlValidatorUtil.alias(node, nextGeneratedId++);
	if (config.identifierExpansion()) {
	// Since we're expanding identifiers, we should make the
	// aliases explicit too, otherwise the expanded query
	// will not be consistent if we convert back to SQL, e.g.
	// "select EXPR$1.EXPR$2 from values (1)".
	newNode = SqlValidatorUtil.addAlias(node, alias);

so need to reuse it

[caicancai]

Thank you for your detailed explanation.

[caicancai]

LGTM

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

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