From a88482dd24aafeca555cf80aa58cf9ae39f25f9d Mon Sep 17 00:00:00 2001 From: Andres Freund Date: Wed, 10 Oct 2018 13:53:02 -0700 Subject: Fix logical decoding error when system table w/ toast is repeatedly rewritten. Repeatedly rewriting a mapped catalog table with VACUUM FULL or CLUSTER could cause logical decoding to fail with: ERROR, "could not map filenode \"%s\" to relation OID" To trigger the problem the rewritten catalog had to have live tuples with toasted columns. The problem was triggered as during catalog table rewrites the heap_insert() check that prevents logical decoding information to be emitted for system catalogs, failed to treat the new heap's toast table as a system catalog (because the new heap is not recognized as a catalog table via RelationIsLogicallyLogged()). The relmapper, in contrast to the normal catalog contents, does not contain historical information. After a single rewrite of a mapped table the new relation is known to the relmapper, but if the table is rewritten twice before logical decoding occurs, the relfilenode cannot be mapped to a relation anymore. Which then leads us to error out. This only happens for toast tables, because the main table contents aren't re-inserted with heap_insert(). The fix is simple, add a new heap_insert() flag that prevents logical decoding information from being emitted, and accept during decoding that there might not be tuple data for toast tables. Unfortunately that does not fix pre-existing logical decoding errors. Doing so would require not throwing an error when a filenode cannot be mapped to a relation during decoding, and that seems too likely to hide bugs. If it's crucial to fix decoding for an existing slot, temporarily changing the ERROR in ReorderBufferCommit() to a WARNING appears to be the best fix. Author: Andres Freund Discussion: https://postgr.es/m/20180914021046.oi7dm4ra3ot2g2kt@alap3.anarazel.de Backpatch: 9.4-, where logical decoding was introduced --- src/backend/access/heap/rewriteheap.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) (limited to 'src/backend/access/heap/rewriteheap.c') diff --git a/src/backend/access/heap/rewriteheap.c b/src/backend/access/heap/rewriteheap.c index bbb04d90e82..e700824d12d 100644 --- a/src/backend/access/heap/rewriteheap.c +++ b/src/backend/access/heap/rewriteheap.c @@ -649,10 +649,23 @@ raw_heap_insert(RewriteState state, HeapTuple tup) heaptup = tup; } else if (HeapTupleHasExternal(tup) || tup->t_len > TOAST_TUPLE_THRESHOLD) + { + int options = HEAP_INSERT_SKIP_FSM; + + if (!state->rs_use_wal) + options |= HEAP_INSERT_SKIP_WAL; + + /* + * The new relfilenode's relcache entrye doesn't have the necessary + * information to determine whether a relation should emit data for + * logical decoding. Force it to off if necessary. + */ + if (!RelationIsLogicallyLogged(state->rs_old_rel)) + options |= HEAP_INSERT_NO_LOGICAL; + heaptup = toast_insert_or_update(state->rs_new_rel, tup, NULL, - HEAP_INSERT_SKIP_FSM | - (state->rs_use_wal ? - 0 : HEAP_INSERT_SKIP_WAL)); + options); + } else heaptup = tup; -- cgit v1.2.3