Merge pull request cockroachdb#48290 from rytaft/backport20.1-48225

release-20.1: opt: fix star expansion of un-labeled tuples

pkg/sql/logictest/testdata/logic_test/srfs

@@ -1087,8 +1087,8 @@ query II colnames
 SELECT (unnest(ARRAY[(1,2),(3,4)])).*
 ----
 ?column?  ?column?
-1         1
-3         3
+1         2
+3         4
 
 query T colnames
 SELECT * FROM unnest(ARRAY[(1,2),(3,4)])

pkg/sql/opt/optbuilder/testdata/project

@@ -229,3 +229,17 @@ project
  │    └── columns: k:1!null v:2
  └── projections
       └── ((v:2, v:2, v:2) AS a, b, c) [as=x:3]
+
+# Regression test for #48179. Star expansion of un-labeled tuple must project
+# all columns from the tuple.
+build
+SELECT (b).* FROM (VALUES (((1, 2)))) as a(b)
+----
+project
+ ├── columns: "?column?":2 "?column?":3
+ ├── values
+ │    ├── columns: column1:1
+ │    └── ((1, 2),)
+ └── projections
+      ├── (column1:1).@1 [as="?column?":2]
+      └── (column1:1).@2 [as="?column?":3]

pkg/sql/opt/optbuilder/util.go

@@ -81,29 +81,32 @@ func (b *Builder) expandStar(
 		tTuple, isTuple := texpr.(*tree.Tuple)
 
 		aliases = typ.TupleLabels()
-		for i := len(aliases); i < len(typ.TupleContents()); i++ {
-			// Add aliases for all the non-named columns in the tuple.
-			aliases = append(aliases, "?column?")
-		}
 		exprs = make([]tree.TypedExpr, len(typ.TupleContents()))
 		for i := range typ.TupleContents() {
 			if isTuple {
 				// De-tuplify: ((a,b,c)).* -> a, b, c
 				exprs[i] = tTuple.Exprs[i].(tree.TypedExpr)
 			} else {
 				// Can't de-tuplify:
-				// either (Expr).* -> (Expr).a, (Expr).b, (Expr).c if there are enough labels,
-				// or (Expr).* -> (Expr).@1, (Expr).@2, (Expr).@3 if labels are missing.
+				// either (Expr).* -> (Expr).a, (Expr).b, (Expr).c if there are enough
+				// labels, or (Expr).* -> (Expr).@1, (Expr).@2, (Expr).@3 if labels are
+				// missing.
 				//
 				// We keep the labels if available so that the column name
 				// generation still produces column label "x" for, e.g. (E).x.
 				colName := ""
-				if i < len(typ.TupleContents()) {
+				if i < len(aliases) {
 					colName = aliases[i]
 				}
+				// NewTypedColumnAccessExpr expects colName to be empty if the tuple
+				// should be accessed by index.
 				exprs[i] = tree.NewTypedColumnAccessExpr(texpr, colName, i)
 			}
 		}
+		for i := len(aliases); i < len(typ.TupleContents()); i++ {
+			// Add aliases for all the non-named columns in the tuple.
+			aliases = append(aliases, "?column?")
+		}
 
 	case *tree.AllColumnsSelector:
 		src, srcMeta, err := t.Resolve(b.ctx, inScope)