From 85efd1a04175951a97b087908121403e4cf4ef7a Mon Sep 17 00:00:00 2001 From: Alvaro Herrera Date: Mon, 19 Nov 2018 11:16:28 -0300 Subject: Disallow COPY FREEZE on partitioned tables This didn't actually work: COPY would fail to flush the right files, and instead would try to flush a non-existing file, causing the whole transaction to fail. Cope by raising an error as soon as the command is sent instead, to avoid a nasty later surprise. Of course, it would be much better to make it work, but we don't have a patch for that yet, and we don't know if we'll want to backpatch one when we do. Reported-by: Tomas Vondra Author: David Rowley Reviewed-by: Amit Langote, Steve Singer, Tomas Vondra --- src/backend/commands/copy.c | 29 +++++++++++++++++++++++++++-- 1 file changed, 27 insertions(+), 2 deletions(-) (limited to 'src/backend/commands/copy.c') diff --git a/src/backend/commands/copy.c b/src/backend/commands/copy.c index 05e05b8fb58..d8aa0c92164 100644 --- a/src/backend/commands/copy.c +++ b/src/backend/commands/copy.c @@ -2382,11 +2382,20 @@ CopyFrom(CopyState cstate) * go into pages containing tuples from any other transactions --- but this * must be the case if we have a new table or new relfilenode, so we need * no additional work to enforce that. + * + * We currently don't support this optimization if the COPY target is a + * partitioned table as we currently only lazily initialize partition + * information when routing the first tuple to the partition. We cannot + * know at this stage if we can perform this optimization. It should be + * possible to improve on this, but it does mean maintaining heap insert + * option flags per partition and setting them when we first open the + * partition. *---------- */ /* createSubid is creation check, newRelfilenodeSubid is truncation check */ - if (cstate->rel->rd_createSubid != InvalidSubTransactionId || - cstate->rel->rd_newRelfilenodeSubid != InvalidSubTransactionId) + if (cstate->rel->rd_rel->relkind != RELKIND_PARTITIONED_TABLE && + (cstate->rel->rd_createSubid != InvalidSubTransactionId || + cstate->rel->rd_newRelfilenodeSubid != InvalidSubTransactionId)) { hi_options |= HEAP_INSERT_SKIP_FSM; if (!XLogIsNeeded()) @@ -2406,6 +2415,22 @@ CopyFrom(CopyState cstate) */ if (cstate->freeze) { + /* + * We currently disallow COPY FREEZE on partitioned tables. The + * reason for this is that we've simply not yet opened the partitions + * to determine if the optimization can be applied to them. We could + * go and open them all here, but doing so may be quite a costly + * overhead for small copies. In any case, we may just end up routing + * tuples to a small number of partitions. It seems better just to + * raise an ERROR for partitioned tables. + */ + if (cstate->rel->rd_rel->relkind == RELKIND_PARTITIONED_TABLE) + { + ereport(ERROR, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("cannot perform FREEZE on a partitioned table"))); + } + /* * Tolerate one registration for the benefit of FirstXactSnapshot. * Scan-bearing queries generally create at least two registrations, -- cgit v1.2.3