On Wed, Nov 16, 2016 at 11:45 AM, Robert Haas <robertmh...@gmail.com> wrote: > The header comment for heap_create_init_fork() says this: > > /* > * Set up an init fork for an unlogged table so that it can be correctly > * reinitialized on restart. Since we're going to do an immediate sync, we > * only need to xlog this if archiving or streaming is enabled. And the > * immediate sync is required, because otherwise there's no guarantee that > * this will hit the disk before the next checkpoint moves the redo pointer. > */ > > Your patch causes the code not to match the comment any more. And the > comment explains why at the time I wrote this code I thought it was OK > to have the XLogIsNeeded() test in there, so it clearly needs > updating.
Indeed I missed this comment block. Please let me suggest the following instead: /* * Set up an init fork for an unlogged table so that it can be correctly - * reinitialized on restart. Since we're going to do an immediate sync, we - * only need to xlog this if archiving or streaming is enabled. And the - * immediate sync is required, because otherwise there's no guarantee that - * this will hit the disk before the next checkpoint moves the redo pointer. + * reinitialized on restart. An immediate sync is required even if the + * page has been logged, because the write did not go through + * shared_buffers and therefore a concurrent checkpoint may have moved + * the redo pointer past our xlog record. */ -- Michael
diff --git a/contrib/bloom/blinsert.c b/contrib/bloom/blinsert.c index 0946aa2..c9c7049 100644 --- a/contrib/bloom/blinsert.c +++ b/contrib/bloom/blinsert.c @@ -164,13 +164,12 @@ blbuildempty(Relation index) metapage = (Page) palloc(BLCKSZ); BloomFillMetapage(index, metapage); - /* Write the page. If archiving/streaming, XLOG it. */ + /* Write the page and log it. */ PageSetChecksumInplace(metapage, BLOOM_METAPAGE_BLKNO); smgrwrite(index->rd_smgr, INIT_FORKNUM, BLOOM_METAPAGE_BLKNO, (char *) metapage, true); - if (XLogIsNeeded()) - log_newpage(&index->rd_smgr->smgr_rnode.node, INIT_FORKNUM, - BLOOM_METAPAGE_BLKNO, metapage, false); + log_newpage(&index->rd_smgr->smgr_rnode.node, INIT_FORKNUM, + BLOOM_METAPAGE_BLKNO, metapage, false); /* * An immediate sync is required even if we xlog'd the page, because the diff --git a/src/backend/access/nbtree/nbtree.c b/src/backend/access/nbtree/nbtree.c index 128744c..624aa84 100644 --- a/src/backend/access/nbtree/nbtree.c +++ b/src/backend/access/nbtree/nbtree.c @@ -242,13 +242,12 @@ btbuildempty(Relation index) metapage = (Page) palloc(BLCKSZ); _bt_initmetapage(metapage, P_NONE, 0); - /* Write the page. If archiving/streaming, XLOG it. */ + /* Write the page and log it */ PageSetChecksumInplace(metapage, BTREE_METAPAGE); smgrwrite(index->rd_smgr, INIT_FORKNUM, BTREE_METAPAGE, (char *) metapage, true); - if (XLogIsNeeded()) - log_newpage(&index->rd_smgr->smgr_rnode.node, INIT_FORKNUM, - BTREE_METAPAGE, metapage, false); + log_newpage(&index->rd_smgr->smgr_rnode.node, INIT_FORKNUM, + BTREE_METAPAGE, metapage, false); /* * An immediate sync is required even if we xlog'd the page, because the diff --git a/src/backend/access/spgist/spginsert.c b/src/backend/access/spgist/spginsert.c index 01c8d21..8ac3b00 100644 --- a/src/backend/access/spgist/spginsert.c +++ b/src/backend/access/spgist/spginsert.c @@ -161,13 +161,12 @@ spgbuildempty(Relation index) page = (Page) palloc(BLCKSZ); SpGistInitMetapage(page); - /* Write the page. If archiving/streaming, XLOG it. */ + /* Write the page and log it. */ PageSetChecksumInplace(page, SPGIST_METAPAGE_BLKNO); smgrwrite(index->rd_smgr, INIT_FORKNUM, SPGIST_METAPAGE_BLKNO, (char *) page, true); - if (XLogIsNeeded()) - log_newpage(&index->rd_smgr->smgr_rnode.node, INIT_FORKNUM, - SPGIST_METAPAGE_BLKNO, page, false); + log_newpage(&index->rd_smgr->smgr_rnode.node, INIT_FORKNUM, + SPGIST_METAPAGE_BLKNO, page, false); /* Likewise for the root page. */ SpGistInitPage(page, SPGIST_LEAF); @@ -175,9 +174,8 @@ spgbuildempty(Relation index) PageSetChecksumInplace(page, SPGIST_ROOT_BLKNO); smgrwrite(index->rd_smgr, INIT_FORKNUM, SPGIST_ROOT_BLKNO, (char *) page, true); - if (XLogIsNeeded()) - log_newpage(&index->rd_smgr->smgr_rnode.node, INIT_FORKNUM, - SPGIST_ROOT_BLKNO, page, true); + log_newpage(&index->rd_smgr->smgr_rnode.node, INIT_FORKNUM, + SPGIST_ROOT_BLKNO, page, true); /* Likewise for the null-tuples root page. */ SpGistInitPage(page, SPGIST_LEAF | SPGIST_NULLS); @@ -185,9 +183,8 @@ spgbuildempty(Relation index) PageSetChecksumInplace(page, SPGIST_NULL_BLKNO); smgrwrite(index->rd_smgr, INIT_FORKNUM, SPGIST_NULL_BLKNO, (char *) page, true); - if (XLogIsNeeded()) - log_newpage(&index->rd_smgr->smgr_rnode.node, INIT_FORKNUM, - SPGIST_NULL_BLKNO, page, true); + log_newpage(&index->rd_smgr->smgr_rnode.node, INIT_FORKNUM, + SPGIST_NULL_BLKNO, page, true); /* * An immediate sync is required even if we xlog'd the pages, because the diff --git a/src/backend/catalog/heap.c b/src/backend/catalog/heap.c index 0cf7b9e..6cd7ce5 100644 --- a/src/backend/catalog/heap.c +++ b/src/backend/catalog/heap.c @@ -1370,18 +1370,17 @@ heap_create_with_catalog(const char *relname, /* * Set up an init fork for an unlogged table so that it can be correctly - * reinitialized on restart. Since we're going to do an immediate sync, we - * only need to xlog this if archiving or streaming is enabled. And the - * immediate sync is required, because otherwise there's no guarantee that - * this will hit the disk before the next checkpoint moves the redo pointer. + * reinitialized on restart. An immediate sync is required even if the + * page has been logged, because the write did not go through + * shared_buffers and therefore a concurrent checkpoint may have moved + * the redo pointer past our xlog record. */ void heap_create_init_fork(Relation rel) { RelationOpenSmgr(rel); smgrcreate(rel->rd_smgr, INIT_FORKNUM, false); - if (XLogIsNeeded()) - log_smgrcreate(&rel->rd_smgr->smgr_rnode.node, INIT_FORKNUM); + log_smgrcreate(&rel->rd_smgr->smgr_rnode.node, INIT_FORKNUM); smgrimmedsync(rel->rd_smgr, INIT_FORKNUM); }
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