Backport 19003

[andyedison]

This PR backports fix for vitessio#18987

upstream PR vitessio#19003

Description

Related Issue(s)

Checklist

• "Backport to:" labels have been added if this change should be back-ported
• Tests were added or are not required
• Documentation was added or is not required

Deployment Notes

[Copilot]

Pull request overview

This PR backports a fix from upstream PR vitessio#19003 that addresses issue vitessio#18987, which relates to proper handling of semantic information when copying expressions in the Vitess query planner, particularly affecting derived tables and subqueries.

• Fixed CopySemanticInfo to validate map keys before copying and to differentiate behavior based on whether the target is a column name
• Improved correlated subquery detection to only check for dependencies on outer tables
• Added comprehensive test coverage for semantic information copying behavior

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
go/vt/vtgate/semantics/semantic_table.go	Enhanced CopySemanticInfo method to add validation checks and conditional copying logic based on target expression type
go/vt/vtgate/semantics/semantic_table_test.go	Added two comprehensive test functions to verify correct behavior when copying semantic information to both ColName and non-ColName expressions
go/vt/vtgate/planbuilder/operators/subquery_builder.go	Fixed correlated subquery detection logic to properly filter dependencies by outerID; added unused createSubqueryFromPath function
go/vt/vtgate/planbuilder/testdata/select_cases.json	Updated test expectations with new window function test cases and minor changes to existing test output

Comments suppressed due to low confidence (1)

go/vt/vtgate/planbuilder/operators/subquery_builder.go:231

• The function createSubqueryFromPath appears to be a duplicate of createSubquery with nearly identical implementation. The only difference is how originalSq is obtained (line 206 uses sqlparser.GetNodeFromPath(original, path) vs line 166 uses cloneASTAndSemState(ctx, subq)). However, this function doesn't appear to be called anywhere in the codebase, suggesting it may be dead code that was accidentally included in this backport.

func createSubqueryFromPath(
	ctx *plancontext.PlanningContext,
	original sqlparser.Expr,
	subq *sqlparser.Subquery,
	path sqlparser.ASTPath,
	outerID semantics.TableSet,
	parent sqlparser.Expr,
	argName string,
	filterType opcode.PulloutOpcode,
	isArg bool,
) *SubQuery {
	topLevel := ctx.SemTable.EqualsExpr(original, parent)
	original = cloneASTAndSemState(ctx, original)
	originalSq := sqlparser.GetNodeFromPath(original, path).(*sqlparser.Subquery)
	subqID := findTablesContained(ctx, originalSq.Select)
	totalID := subqID.Merge(outerID)
	sqc := &SubQueryBuilder{totalID: totalID, subqID: subqID, outerID: outerID}

	predicates, joinCols := sqc.inspectStatement(ctx, subq.Select)

	subqDependencies := ctx.SemTable.RecursiveDeps(subq)
	correlated := subqDependencies.KeepOnly(outerID).NotEmpty()

	opInner := translateQueryToOp(ctx, subq.Select)

	opInner = sqc.getRootOperator(opInner, nil)
	return &SubQuery{
		FilterType:       filterType,
		Subquery:         opInner,
		Predicates:       predicates,
		Original:         original,
		ArgName:          argName,
		originalSubquery: originalSq,
		IsArgument:       isArg,
		TopLevel:         topLevel,
		JoinColumns:      joinCols,
		correlated:       correlated,
	}
}

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