From c4c51541e22bf7f2da8ecf6986271687b0d7a90e Mon Sep 17 00:00:00 2001 From: Robert Haas Date: Mon, 27 Mar 2017 12:50:51 -0400 Subject: [PATCH] Still more code review for single-page hash vacuuming. Most seriously, fix use of incorrect block ID, per a report from Jeff Janes that it causes a crash and a diagnosis from Amit Kapila. Improve consistency between the hash and btree versions of this code by adding back a PANIC that btree has, and by registering data in the xlog record in the same way, per complaints from Jeff Janes and Amit Kapila. Tidy up some minor cosmetic points, per complaints from Amit Kapila. Patch by Ashutosh Sharma, reviewed by Amit Kapila, and tested by Jeff Janes. Discussion: http://postgr.es/m/CAMkU=1w-9Qe=Ff1o6bSaXpNO9wqpo7_9GL8_CVhw4BoVVHasqg@mail.gmail.com --- src/backend/access/hash/hash_xlog.c | 30 +++++++++++--------------- src/backend/access/hash/hashinsert.c | 17 ++++++++------- src/backend/access/rmgrdesc/hashdesc.c | 2 +- src/include/access/hash_xlog.h | 6 ++++-- 4 files changed, 27 insertions(+), 28 deletions(-) diff --git a/src/backend/access/hash/hash_xlog.c b/src/backend/access/hash/hash_xlog.c index de7522ea01..d9ac42c394 100644 --- a/src/backend/access/hash/hash_xlog.c +++ b/src/backend/access/hash/hash_xlog.c @@ -957,8 +957,6 @@ hash_xlog_vacuum_get_latestRemovedXid(XLogReaderState *record) OffsetNumber hoffnum; TransactionId latestRemovedXid = InvalidTransactionId; int i; - char *ptr; - Size len; xlrec = (xl_hash_vacuum_one_page *) XLogRecGetData(record); @@ -976,13 +974,21 @@ hash_xlog_vacuum_get_latestRemovedXid(XLogReaderState *record) if (CountDBBackends(InvalidOid) == 0) return latestRemovedXid; + /* + * Check if WAL replay has reached a consistent database state. If not, + * we must PANIC. See the definition of btree_xlog_delete_get_latestRemovedXid + * for more details. + */ + if (!reachedConsistency) + elog(PANIC, "hash_xlog_vacuum_get_latestRemovedXid: cannot operate with inconsistent data"); + /* * Get index page. If the DB is consistent, this should not fail, nor * should any of the heap page fetches below. If one does, we return * InvalidTransactionId to cancel all HS transactions. That's probably * overkill, but it's safe, and certainly better than panicking here. */ - XLogRecGetBlockTag(record, 1, &rnode, NULL, &blkno); + XLogRecGetBlockTag(record, 0, &rnode, NULL, &blkno); ibuffer = XLogReadBufferExtended(rnode, MAIN_FORKNUM, blkno, RBM_NORMAL); if (!BufferIsValid(ibuffer)) @@ -994,9 +1000,7 @@ hash_xlog_vacuum_get_latestRemovedXid(XLogReaderState *record) * Loop through the deleted index items to obtain the TransactionId from * the heap items they point to. */ - ptr = XLogRecGetBlockData(record, 1, &len); - - unused = (OffsetNumber *) ptr; + unused = (OffsetNumber *) ((char *) xlrec + SizeOfHashVacuumOnePage); for (i = 0; i < xlrec->ntuples; i++) { @@ -1121,23 +1125,15 @@ hash_xlog_vacuum_one_page(XLogReaderState *record) if (action == BLK_NEEDS_REDO) { - char *ptr; - Size len; - - ptr = XLogRecGetBlockData(record, 0, &len); - page = (Page) BufferGetPage(buffer); - if (len > 0) + if (XLogRecGetDataLen(record) > SizeOfHashVacuumOnePage) { OffsetNumber *unused; - OffsetNumber *unend; - unused = (OffsetNumber *) ptr; - unend = (OffsetNumber *) ((char *) ptr + len); + unused = (OffsetNumber *) ((char *) xldata + SizeOfHashVacuumOnePage); - if ((unend - unused) > 0) - PageIndexMultiDelete(page, unused, unend - unused); + PageIndexMultiDelete(page, unused, xldata->ntuples); } /* diff --git a/src/backend/access/hash/hashinsert.c b/src/backend/access/hash/hashinsert.c index 8640e85a5c..8699b5bc30 100644 --- a/src/backend/access/hash/hashinsert.c +++ b/src/backend/access/hash/hashinsert.c @@ -344,7 +344,6 @@ _hash_vacuum_one_page(Relation rel, Buffer metabuf, Buffer buf, Page page = BufferGetPage(buf); HashPageOpaque pageopaque; HashMetaPage metap; - double tuples_removed = 0; /* Scan each tuple in page to see if it is marked as LP_DEAD */ maxoff = PageGetMaxOffsetNumber(page); @@ -355,10 +354,7 @@ _hash_vacuum_one_page(Relation rel, Buffer metabuf, Buffer buf, ItemId itemId = PageGetItemId(page, offnum); if (ItemIdIsDead(itemId)) - { deletable[ndeletable++] = offnum; - tuples_removed += 1; - } } if (ndeletable > 0) @@ -386,7 +382,7 @@ _hash_vacuum_one_page(Relation rel, Buffer metabuf, Buffer buf, pageopaque->hasho_flag &= ~LH_PAGE_HAS_DEAD_TUPLES; metap = HashPageGetMeta(BufferGetPage(metabuf)); - metap->hashm_ntuples -= tuples_removed; + metap->hashm_ntuples -= ndeletable; MarkBufferDirty(buf); MarkBufferDirty(metabuf); @@ -398,13 +394,18 @@ _hash_vacuum_one_page(Relation rel, Buffer metabuf, Buffer buf, XLogRecPtr recptr; xlrec.hnode = hnode; - xlrec.ntuples = tuples_removed; + xlrec.ntuples = ndeletable; XLogBeginInsert(); + XLogRegisterBuffer(0, buf, REGBUF_STANDARD); XLogRegisterData((char *) &xlrec, SizeOfHashVacuumOnePage); - XLogRegisterBuffer(0, buf, REGBUF_STANDARD); - XLogRegisterBufData(0, (char *) deletable, + /* + * We need the target-offsets array whether or not we store the whole + * buffer, to allow us to find the latestRemovedXid on a standby + * server. + */ + XLogRegisterData((char *) deletable, ndeletable * sizeof(OffsetNumber)); XLogRegisterBuffer(1, metabuf, REGBUF_STANDARD); diff --git a/src/backend/access/rmgrdesc/hashdesc.c b/src/backend/access/rmgrdesc/hashdesc.c index 5f5f4a0255..35d86dc893 100644 --- a/src/backend/access/rmgrdesc/hashdesc.c +++ b/src/backend/access/rmgrdesc/hashdesc.c @@ -113,7 +113,7 @@ hash_desc(StringInfo buf, XLogReaderState *record) { xl_hash_vacuum_one_page *xlrec = (xl_hash_vacuum_one_page *) rec; - appendStringInfo(buf, "ntuples %g", + appendStringInfo(buf, "ntuples %d", xlrec->ntuples); break; } diff --git a/src/include/access/hash_xlog.h b/src/include/access/hash_xlog.h index 2e64cfa3ea..644da2eaf2 100644 --- a/src/include/access/hash_xlog.h +++ b/src/include/access/hash_xlog.h @@ -265,11 +265,13 @@ typedef struct xl_hash_init_bitmap_page typedef struct xl_hash_vacuum_one_page { RelFileNode hnode; - double ntuples; + int ntuples; + + /* TARGET OFFSET NUMBERS FOLLOW AT THE END */ } xl_hash_vacuum_one_page; #define SizeOfHashVacuumOnePage \ - (offsetof(xl_hash_vacuum_one_page, ntuples) + sizeof(double)) + (offsetof(xl_hash_vacuum_one_page, ntuples) + sizeof(int)) extern void hash_redo(XLogReaderState *record); extern void hash_desc(StringInfo buf, XLogReaderState *record);