diff options
Diffstat (limited to 'src/backend/commands/tablecmds.c')
| -rw-r--r-- | src/backend/commands/tablecmds.c | 27 |
1 files changed, 19 insertions, 8 deletions
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index 87a2fb4856d..a7eac55f252 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.125 2004/08/13 04:50:28 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.126 2004/08/15 23:44:46 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -5479,18 +5479,29 @@ copy_relation_data(Relation rel, SMgrRelation dst) } /* - * Now write the page. If not using WAL, say isTemp = true, to - * suppress duplicate fsync. If we are using WAL, it surely isn't a - * temp rel, so !use_wal is a sufficient condition. + * Now write the page. We say isTemp = true even if it's not a + * temp rel, because there's no need for smgr to schedule an fsync + * for this write; we'll do it ourselves below. */ - smgrwrite(dst, blkno, buf, !use_wal); + smgrwrite(dst, blkno, buf, true); } /* - * If we weren't using WAL, and the rel isn't temp, we must fsync it - * down to disk before it's safe to commit the transaction. + * If the rel isn't temp, we must fsync it down to disk before it's + * safe to commit the transaction. (For a temp rel we don't care + * since the rel will be uninteresting after a crash anyway.) + * + * It's obvious that we must do this when not WAL-logging the copy. + * It's less obvious that we have to do it even if we did WAL-log the + * copied pages. The reason is that since we're copying outside + * shared buffers, a CHECKPOINT occurring during the copy has no way + * to flush the previously written data to disk (indeed it won't know + * the new rel 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 (!use_wal && !rel->rd_istemp) + if (!rel->rd_istemp) smgrimmedsync(dst); } |