+ * Custom scan nodes can be leaf nodes or inner nodes and therfore need special treatment.
The special treatment applies to inner nodes. The above should be better phrased to clarify.
Cheers
On Mon, Jan 18, 2021 at 2:43 AM David Geier <david@swarm64.com> wrote:
Hi hackers,
While working with cursors that reference plans with CustomScanStates nodes, I encountered a segfault which originates from search_plan_tree(). The query plan is the result of a simple SELECT statement into which I inject a Custom Scan node at the root to do some post-processing before returning rows. This plan is referenced by a second plan with a Tid Scan which originates from a query of the form DELETE FROM foo WHERE CURRENT OF my_cursor;
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.