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| author | Thomas Munro <tmunro@postgresql.org> | 2020-02-05 12:21:03 +1300 |
|---|---|---|
| committer | Thomas Munro <tmunro@postgresql.org> | 2020-02-05 12:30:06 +1300 |
| commit | c4a2041a43c92c566c42c7ae8029868be317f8d9 (patch) | |
| tree | 3a4b4fe1a4f291f5a30c8645fa35d99a0e80d282 /src | |
| parent | 842a23efa92ab5ac91e013968e7575782fc1ebf1 (diff) | |
| download | postgresql-c4a2041a43c92c566c42c7ae8029868be317f8d9.tar.gz postgresql-c4a2041a43c92c566c42c7ae8029868be317f8d9.zip | |
Handle lack of DSM slots in parallel btree build, take 2.
Commit 74618e77 added a new check intended to fix a bug, but put
it in the wrong place so that parallel btree build was always
disabled. Do the check after we've actually tried to create
a DSM segment. Back-patch to 11, like the earlier commit.
Reviewed-by: Peter Geoghegan
Discussion: https://postgr.es/m/CAH2-WzmDABkJzrNnvf%2BOULK-_A_j9gkYg_Dz-H62jzNv4eKQTw%40mail.gmail.com
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/access/nbtree/nbtsort.c | 18 |
1 files changed, 10 insertions, 8 deletions
diff --git a/src/backend/access/nbtree/nbtsort.c b/src/backend/access/nbtree/nbtsort.c index bc00799b964..dab41ea298a 100644 --- a/src/backend/access/nbtree/nbtsort.c +++ b/src/backend/access/nbtree/nbtsort.c @@ -1257,14 +1257,6 @@ _bt_begin_parallel(BTBuildState *buildstate, bool isconcurrent, int request) pcxt = CreateParallelContext("postgres", "_bt_parallel_build_main", request, true); - /* If no DSM segment was available, back out (do serial build) */ - if (pcxt->seg == NULL) - { - DestroyParallelContext(pcxt); - ExitParallelMode(); - return; - } - scantuplesortstates = leaderparticipates ? request + 1 : request; /* @@ -1308,6 +1300,16 @@ _bt_begin_parallel(BTBuildState *buildstate, bool isconcurrent, int request) /* Everyone's had a chance to ask for space, so now create the DSM */ InitializeParallelDSM(pcxt); + /* If no DSM segment was available, back out (do serial build) */ + if (pcxt->seg == NULL) + { + if (IsMVCCSnapshot(snapshot)) + UnregisterSnapshot(snapshot); + DestroyParallelContext(pcxt); + ExitParallelMode(); + return; + } + /* Store shared build state, for which we reserved space */ btshared = (BTShared *) shm_toc_allocate(pcxt->toc, estbtshared); /* Initialize immutable state */ |