diff options
Diffstat (limited to 'src/backend/access/nbtree/nbtsort.c')
| -rw-r--r-- | src/backend/access/nbtree/nbtsort.c | 41 |
1 files changed, 9 insertions, 32 deletions
diff --git a/src/backend/access/nbtree/nbtsort.c b/src/backend/access/nbtree/nbtsort.c index 4a85865fc50..29a6f5ade61 100644 --- a/src/backend/access/nbtree/nbtsort.c +++ b/src/backend/access/nbtree/nbtsort.c @@ -31,18 +31,6 @@ * them. They will need to be re-read into shared buffers on first use after * the build finishes. * - * Since the index will never be used unless it is completely built, - * from a crash-recovery point of view there is no need to WAL-log the - * steps of the build. After completing the index build, we can just sync - * the whole file to disk using smgrimmedsync() before exiting this module. - * This can be seen to be sufficient for crash recovery by considering that - * it's effectively equivalent to what would happen if a CHECKPOINT occurred - * just after the index build. However, it is clearly not sufficient if the - * DBA is using the WAL log for PITR or replication purposes, since another - * machine would not be able to reconstruct the index from WAL. Therefore, - * we log the completed index pages to WAL if and only if WAL archiving is - * active. - * * This code isn't concerned about the FSM at all. The caller is responsible * for initializing that. * @@ -572,12 +560,7 @@ _bt_leafbuild(BTSpool *btspool, BTSpool *btspool2) wstate.inskey = _bt_mkscankey(wstate.index, NULL); /* _bt_mkscankey() won't set allequalimage without metapage */ wstate.inskey->allequalimage = _bt_allequalimage(wstate.index, true); - - /* - * We need to log index creation in WAL iff WAL archiving/streaming is - * enabled UNLESS the index isn't WAL-logged anyway. - */ - wstate.btws_use_wal = XLogIsNeeded() && RelationNeedsWAL(wstate.index); + wstate.btws_use_wal = RelationNeedsWAL(wstate.index); /* reserve the metapage */ wstate.btws_pages_alloced = BTREE_METAPAGE + 1; @@ -1429,21 +1412,15 @@ _bt_load(BTWriteState *wstate, BTSpool *btspool, BTSpool *btspool2) _bt_uppershutdown(wstate, state); /* - * If the index is WAL-logged, we must fsync it down to disk before it's - * safe to commit the transaction. (For a non-WAL-logged index we don't - * care since the index will be uninteresting after a crash anyway.) - * - * It's obvious that we must do this when not WAL-logging the build. It's - * less obvious that we have to do it even if we did WAL-log the index - * pages. The reason is that since we're building outside shared buffers, - * a CHECKPOINT occurring during the build has no way to flush the - * previously written data to disk (indeed it won't know the index even - * exists). A crash later on would replay WAL from the checkpoint, - * therefore it wouldn't replay our earlier WAL entries. If we do not - * fsync those pages here, they might still not be on disk when the crash - * occurs. + * When we WAL-logged index pages, we must nonetheless fsync index files. + * Since we're building outside shared buffers, a CHECKPOINT occurring + * during the build has no way to flush the previously written data to + * disk (indeed it won't know the index even exists). A crash later on + * would replay WAL from the checkpoint, therefore it wouldn't replay our + * earlier WAL entries. If we do not fsync those pages here, they might + * still not be on disk when the crash occurs. */ - if (RelationNeedsWAL(wstate->index)) + if (wstate->btws_use_wal) { RelationOpenSmgr(wstate->index); smgrimmedsync(wstate->index->rd_smgr, MAIN_FORKNUM); |