diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/access/brin/brin.c | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/src/backend/access/brin/brin.c b/src/backend/access/brin/brin.c index 5e662a4d4ee..dfa34f49a4f 100644 --- a/src/backend/access/brin/brin.c +++ b/src/backend/access/brin/brin.c @@ -1040,16 +1040,22 @@ brinbuildCallbackParallel(Relation index, thisblock = ItemPointerGetBlockNumber(tid); /* - * If we're in a block that belongs to a future range, summarize what + * If we're in a block that belongs to a different range, summarize what * we've got and start afresh. Note the scan might have skipped many * pages, if they were devoid of live tuples; we do not create emptry BRIN * ranges here - the leader is responsible for filling them in. + * + * Unlike serial builds, parallel index builds allow synchronized seqscans + * (because that's what parallel scans do). This means the block may wrap + * around to the beginning of the relation, so the condition needs to + * check for both future and past ranges. */ - if (thisblock > state->bs_currRangeStart + state->bs_pagesPerRange - 1) + if ((thisblock < state->bs_currRangeStart) || + (thisblock > state->bs_currRangeStart + state->bs_pagesPerRange - 1)) { BRIN_elog((DEBUG2, - "brinbuildCallback: completed a range: %u--%u", + "brinbuildCallbackParallel: completed a range: %u--%u", state->bs_currRangeStart, state->bs_currRangeStart + state->bs_pagesPerRange)); @@ -1201,7 +1207,9 @@ brinbuild(Relation heap, Relation index, IndexInfo *indexInfo) { /* * Now scan the relation. No syncscan allowed here because we want - * the heap blocks in physical order. + * the heap blocks in physical order (we want to produce the ranges + * starting from block 0, and the callback also relies on this to not + * generate summary for the same range twice). */ reltuples = table_index_build_scan(heap, index, indexInfo, false, true, brinbuildCallback, (void *) state, NULL); |