diff --git a/pkg/sql/opt/norm/join_funcs.go b/pkg/sql/opt/norm/join_funcs.go
index aa70eb101503..7bdd1f9f8f4e 100644
--- a/pkg/sql/opt/norm/join_funcs.go
+++ b/pkg/sql/opt/norm/join_funcs.go
@@ -553,7 +553,13 @@ func (c *CustomFuncs) ExtractJoinEquality(
 	)
 
 	// Project away the synthesized columns.
-	return c.f.ConstructProject(join, memo.EmptyProjectionsExpr, leftCols.Union(rightCols))
+	outputCols := leftCols
+	if joinOp != opt.SemiJoinOp && joinOp != opt.AntiJoinOp {
+		// Semi/Anti join only produce the left side columns. All other join types
+		// produce columns from both sides.
+		outputCols = leftCols.Union(rightCols)
+	}
+	return c.f.ConstructProject(join, memo.EmptyProjectionsExpr, outputCols)
 }
 
 // CommuteJoinFlags returns a join private for the commuted join (where the left