diff --git a/src/backend/executor/execPartition.c b/src/backend/executor/execPartition.c index bb14dcbe6f..9a9f93771a 100644 --- a/src/backend/executor/execPartition.c +++ b/src/backend/executor/execPartition.c @@ -1942,37 +1942,31 @@ CreatePartitionPruneState(PlanState *planstate, PartitionPruneInfo *pruneinfo) /* * Initialize the subplan_map and subpart_map. * - * Because we request detached partitions to be included, and - * detaching waits for old transactions, it is safe to assume that - * no partitions have disappeared since this query was planned. + * The set of partitions that exist now might not be the same that + * existed when the plan was made. The normal case is that it is; + * optimize for that case with a quick comparison, and just copy + * the subplan_map and make subpart_map point to the one in + * PruneInfo. * - * However, new partitions may have been added. + * For the case where they aren't identical, we could have more + * partitions on either side; or even exactly the same number of + * them on both but the set of OIDs doesn't match fully. Handle + * this by creating new subplan_map and subpart_map arrays that + * corresponds to the ones in the PruneInfo where the new + * partition descriptor's OIDs match. Any that don't match can be + * set to -1, as if they were pruned. Both arrays must be in + * numerical OID order. */ - Assert(partdesc->nparts >= pinfo->nparts); pprune->nparts = partdesc->nparts; pprune->subplan_map = palloc(sizeof(int) * partdesc->nparts); - if (partdesc->nparts == pinfo->nparts) + + if (partdesc->nparts == pinfo->nparts && + memcmp(partdesc->oids, pinfo->relid_map, + sizeof(int) * partdesc->nparts) == 0) { - /* - * There are no new partitions, so this is simple. We can - * simply point to the subpart_map from the plan, but we must - * copy the subplan_map since we may change it later. - */ pprune->subpart_map = pinfo->subpart_map; memcpy(pprune->subplan_map, pinfo->subplan_map, sizeof(int) * pinfo->nparts); - - /* - * Double-check that the list of unpruned relations has not - * changed. (Pruned partitions are not in relid_map[].) - */ -#ifdef USE_ASSERT_CHECKING - for (int k = 0; k < pinfo->nparts; k++) - { - Assert(partdesc->oids[k] == pinfo->relid_map[k] || - pinfo->subplan_map[k] == -1); - } -#endif } else { @@ -1980,22 +1974,18 @@ CreatePartitionPruneState(PlanState *planstate, PartitionPruneInfo *pruneinfo) int pp_idx; /* - * Some new partitions have appeared since plan time, and - * those are reflected in our PartitionDesc but were not - * present in the one used to construct subplan_map and - * subpart_map. So we must construct new and longer arrays - * where the partitions that were originally present map to - * the same sub-structures, and any added partitions map to - * -1, as if the new partitions had been pruned. + * When the partition arrays are not identical, there could be + * some new ones but it's also possible that one was removed; + * we cope with both situations by walking the arrays and + * discarding those that don't match. * - * Note: pinfo->relid_map[] may contain InvalidOid entries for - * partitions pruned by the planner. We cannot tell exactly - * which of the partdesc entries these correspond to, but we - * don't have to; just skip over them. The non-pruned - * relid_map entries, however, had better be a subset of the - * partdesc entries and in the same order. + * If the number of partitions on both sides match, it's still + * possible that one partition has been detached and another + * attached. Cope with that by creating a map that skips any + * mismatches. */ pprune->subpart_map = palloc(sizeof(int) * partdesc->nparts); + for (pp_idx = 0; pp_idx < partdesc->nparts; pp_idx++) { /* Skip any InvalidOid relid_map entries */ @@ -2003,6 +1993,7 @@ CreatePartitionPruneState(PlanState *planstate, PartitionPruneInfo *pruneinfo) !OidIsValid(pinfo->relid_map[pd_idx])) pd_idx++; + recheck: if (pd_idx < pinfo->nparts && pinfo->relid_map[pd_idx] == partdesc->oids[pp_idx]) { @@ -2012,24 +2003,41 @@ CreatePartitionPruneState(PlanState *planstate, PartitionPruneInfo *pruneinfo) pprune->subpart_map[pp_idx] = pinfo->subpart_map[pd_idx]; pd_idx++; + continue; } - else - { - /* this partdesc entry is not in the plan */ - pprune->subplan_map[pp_idx] = -1; - pprune->subpart_map[pp_idx] = -1; - } - } - /* - * It might seem that we need to skip any trailing InvalidOid - * entries in pinfo->relid_map before checking that we scanned - * all of the relid_map. But we will have skipped them above, - * because they must correspond to some partdesc->oids - * entries; we just couldn't tell which. - */ - if (pd_idx != pinfo->nparts) - elog(ERROR, "could not match partition child tables to plan elements"); + /* + * There isn't an exact match in the corresponding + * positions of both arrays. Peek ahead in + * pinfo->relid_map to see if we have a match for the + * current partition in partdesc. Normally if a match + * exists it's just one element ahead, and it means the + * planner saw one extra partition that we no longer see + * now (its concurrent detach finished just in between); + * so we skip that one by updating pd_idx to the new + * location and jumping above. We can then continue to + * match the rest of the elements after skipping the OID + * with no match; no future matches are tried for the + * element that was skipped, because we know the arrays to + * be in the same order. + * + * If we don't see a match anywhere in the rest of the + * pinfo->relid_map array, that means we see an element + * now that the planner didn't see, so mark that one as + * pruned and move on. + */ + for (int pd_idx2 = pd_idx + 1; pd_idx2 < pinfo->nparts; pd_idx2++) + { + if (pinfo->relid_map[pd_idx2] == partdesc->oids[pp_idx]) + { + pd_idx = pd_idx2; + goto recheck; + } + } + + pprune->subpart_map[pp_idx] = -1; + pprune->subplan_map[pp_idx] = -1; + } } /* present_parts is also subject to later modification */ -- 2.39.2