diff options
Diffstat (limited to 'src/backend/optimizer/util/pathnode.c')
| -rw-r--r-- | src/backend/optimizer/util/pathnode.c | 19 |
1 files changed, 18 insertions, 1 deletions
diff --git a/src/backend/optimizer/util/pathnode.c b/src/backend/optimizer/util/pathnode.c index b248b038e03..9ce5f95e3b1 100644 --- a/src/backend/optimizer/util/pathnode.c +++ b/src/backend/optimizer/util/pathnode.c @@ -2632,7 +2632,23 @@ create_projection_path(PlannerInfo *root, PathTarget *target) { ProjectionPath *pathnode = makeNode(ProjectionPath); - PathTarget *oldtarget = subpath->pathtarget; + PathTarget *oldtarget; + + /* + * We mustn't put a ProjectionPath directly above another; it's useless + * and will confuse create_projection_plan. Rather than making sure all + * callers handle that, let's implement it here, by stripping off any + * ProjectionPath in what we're given. Given this rule, there won't be + * more than one. + */ + if (IsA(subpath, ProjectionPath)) + { + ProjectionPath *subpp = (ProjectionPath *) subpath; + + Assert(subpp->path.parent == rel); + subpath = subpp->subpath; + Assert(!IsA(subpath, ProjectionPath)); + } pathnode->path.pathtype = T_Result; pathnode->path.parent = rel; @@ -2658,6 +2674,7 @@ create_projection_path(PlannerInfo *root, * Note: in the latter case, create_projection_plan has to recheck our * conclusion; see comments therein. */ + oldtarget = subpath->pathtarget; if (is_projection_capable_path(subpath) || equal(oldtarget->exprs, target->exprs)) { |