vitessio/vitess · error

VT09015

VT09015

Error message

VT09015

What it means

Horizon.FindCol iterates the first SELECT's column list expecting every select expression to be *sqlparser.AliasedExpr. Any other SelectExpr kind (e.g. a star expression that wasn't expanded) triggers VT09015, which signals the query contains something the planner does not support.

Source

Thrown at go/vt/vtgate/planbuilder/operators/horizon.go:165

		if ctx.SemTable.EqualsExprWithDeps(col, f(column)) {
			return offset, true
		}
	}

	return
}

func (h *Horizon) FindCol(ctx *plancontext.PlanningContext, expr sqlparser.Expr, underRoute bool) int {
	if underRoute && h.IsDerived() {
		// We don't want to use columns on this operator if it's a derived table under a route.
		// In this case, we need to add a Projection on top of this operator to make the column available
		return -1
	}

	for idx, se := range getFirstSelect(h.Query).GetColumns() {
		ae, ok := se.(*sqlparser.AliasedExpr)
		if !ok {
			panic(vterrors.VT09015())
		}
		if ctx.SemTable.EqualsExprWithDeps(ae.Expr, expr) {
			return idx
		}
	}

	return -1
}

func (h *Horizon) GetColumns(ctx *plancontext.PlanningContext) (exprs []*sqlparser.AliasedExpr) {
	for _, expr := range ctx.SemTable.SelectExprs(h.Query) {
		ae, ok := expr.(*sqlparser.AliasedExpr)
		if !ok {
			panic(vterrors.VT09015())
		}
		exprs = append(exprs, ae)
	}

View on GitHub (pinned to 01a25a7d17)

Solutions

1. Ensure star expressions are expanded (semantics 'expandStar') before horizon column matching runs
2. Rewrite the query to use explicit column lists instead of SELECT *
3. If reproducible, file a Vitess bug — VT09015 marks an unsupported query feature

Example fix

-- before
SELECT * FROM (SELECT * FROM tbl) t ORDER BY a
-- after
SELECT a FROM (SELECT a FROM tbl) t ORDER BY a

func allAliasedExprs(stmt sqlparser.TableStatement) bool {
    for _, se := range getFirstSelect(stmt).GetColumns() {
        if _, ok := se.(*sqlparser.AliasedExpr); !ok { return false }
    }
    return true
}

When it happens

Trigger: Calling FindCol (directly or via AddColumn) on a horizon whose first SELECT still contains non-AliasedExpr select items, such as unexpanded '*' or qualified star expressions.

Common situations: Planner stages running before star expansion completed; queries with SELECT * in derived tables hitting a code path that assumes expanded columns.

Related errors

• VT13001
• query not supported by vexec
• Not implemented, post_header_length!=8
• Not implemented, post_header_length==6
• VT09015

AI-assisted analysis of vitessio/vitess@01a25a7d17 (2026-09-01). Data as JSON: /api/errors/160198d7b3a29cdc. Report an issue: GitHub.