It seems sstate->ss_currentRelation being null can only occur for T_ForeignScanState and T_CustomScanState.
What about the following change ?
Cheers
diff --git a/src/backend/executor/execCurrent.c b/src/backend/executor/execCurrent.c index 0852bb9cec..56e31951d1 100644 --- a/src/backend/executor/execCurrent.c +++ b/src/backend/executor/execCurrent.c @@ -325,12 +325,21 @@ search_plan_tree(PlanState *node, Oid table_oid, case T_IndexOnlyScanState: case T_BitmapHeapScanState: case T_TidScanState: + { + ScanState *sstate = (ScanState *) node; + + if (RelationGetRelid(sstate->ss_currentRelation) == table_oid) + result = sstate; + break; + } + case T_ForeignScanState: case T_CustomScanState: { ScanState *sstate = (ScanState *) node;
- if (RelationGetRelid(sstate->ss_currentRelation) == table_oid) + if (sstate->ss_currentRelation && + RelationGetRelid(sstate->ss_currentRelation) == table_oid) result = sstate; break; }
On Mon, Jan 18, 2021 at 10:46 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
David Geier <david@swarm64.com> writes: > search_plan_tree() assumes that > CustomScanState::ScanState::ss_currentRelation is never NULL. In my > understanding that only holds for CustomScanState nodes which are at the > bottom of the plan and actually read from a relation. CustomScanState > nodes which are not at the bottom don't have ss_currentRelation set. I > believe for such nodes, instead search_plan_tree() should recurse into > CustomScanState::custom_ps.
Hm. I agree that we shouldn't simply assume that ss_currentRelation isn't null. However, we cannot make search_plan_tree() descend through non-leaf CustomScan nodes, because we don't know what processing is involved there. We need to find a scan that is guaranteed to return rows that are one-to-one with the cursor output. This is why the function doesn't descend through join or aggregation nodes, and I see no argument by which we should assume we know more about what a customscan node will do than we know about those.
So I'm inclined to think a suitable fix is just
- if (RelationGetRelid(sstate->ss_currentRelation) == table_oid) + if (sstate->ss_currentRelation && + RelationGetRelid(sstate->ss_currentRelation) == table_oid) result = sstate;
