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Still more code review for single-page hash vacuuming.

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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
This commit is contained in:
Robert Haas 2017-03-27 12:50:51 -04:00
parent 1b02be21f2
commit c4c51541e2
4 changed files with 27 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

30
src/backend/access/hash/hash_xlog.c
View File

@ -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);
}
/*

17
src/backend/access/hash/hashinsert.c
View File

@ -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);

2
src/backend/access/rmgrdesc/hashdesc.c
View File

@ -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;
}

6
src/include/access/hash_xlog.h
View File

@ -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);