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Preserve subquery input expressions in EXPLAIN queries #500

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Merged
nicktobey merged 2 commits into from
Oct 7, 2026
Merged

Preserve subquery input expressions in EXPLAIN queries #500

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3621ee3
Implement WalkableNode for the Explain node.
nicktobey Oct 7, 2026
2ae389b
Add test for input expression in explain.
nicktobey Oct 7, 2026
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6 changes: 6 additions & 0 deletions go/vt/sqlparser/ast.go
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Original file line number Diff line number Diff line change
Expand Up @@ -4144,6 +4144,8 @@ type Explain struct {
Analyze bool
}

var _ WalkableSQLNode = &Explain{}

// Format formats the node.
func (node *Explain) Format(buf *TrackedBuffer) {
analyzeOpt := ""
Expand All @@ -4161,6 +4163,10 @@ func (node *Explain) Format(buf *TrackedBuffer) {
buf.Myprintf("explain %s%s%s%v", analyzeOpt, formatOpt, planOpt, node.Statement)
}

func (node *Explain) walkSubtree(visit Visit) error {
return Walk(visit, node.Statement)
}

const (
CreateTriggerStr = "create trigger"
CreateProcedureStr = "create procedure"
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16 changes: 16 additions & 0 deletions go/vt/sqlparser/ast_test.go
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Expand Up @@ -142,6 +142,22 @@ func TestInsertOnDupWhereFormatAndWalk(t *testing.T) {
require.True(t, visitedPredicate)
}

func TestInputExpressionInExplain(t *testing.T) {
stmt, err := Parse("explain select (select 1)")
require.NoError(t, err)
var inputExpression string
require.NoError(t, Walk(func(node SQLNode) (bool, error) {
if ae, ok := node.(*AliasedExpr); ok {
if _, ok := ae.Expr.(*Subquery); ok {
inputExpression = ae.InputExpression
return false, nil
}
}
return true, nil
}, stmt))
require.Equal(t, inputExpression, "(select 1)")
}

func TestRemoveHints(t *testing.T) {
for _, query := range []string{
"select * from t use index (i)",
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