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Commitefd6cad

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committed
Tweak heap_update/delete so that we do not hold the buffer context lock
on the old tuple's page while we are doing TOAST pushups.
1 parent0b5d194 commitefd6cad

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2 files changed

+74
-51
lines changed

2 files changed

+74
-51
lines changed

‎src/backend/access/heap/heapam.c

Lines changed: 68 additions & 47 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/access/heap/heapam.c,v 1.107 2001/01/12 21:53:54 tgl Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/access/heap/heapam.c,v 1.108 2001/01/15 05:29:19 tgl Exp $
1212
*
1313
*
1414
* INTERFACE ROUTINES
@@ -1534,18 +1534,20 @@ heap_delete(Relation relation, ItemPointer tid, ItemPointer ctid)
15341534
}
15351535
END_CRIT_SECTION();
15361536

1537+
LockBuffer(buffer,BUFFER_LOCK_UNLOCK);
1538+
15371539
#ifdefTUPLE_TOASTER_ACTIVE
15381540
/* ----------
15391541
* If the relation has toastable attributes, we need to delete
1540-
* no longer needed items there too.
1542+
* no longer needed items there too. We have to do this before
1543+
* WriteBuffer because we need to look at the contents of the tuple,
1544+
* but it's OK to release the context lock on the buffer first.
15411545
* ----------
15421546
*/
15431547
if (HeapTupleHasExtended(&tp))
15441548
heap_tuple_toast_attrs(relation,NULL,&(tp));
15451549
#endif
15461550

1547-
LockBuffer(buffer,BUFFER_LOCK_UNLOCK);
1548-
15491551
/*
15501552
* Mark tuple for invalidation from system caches at next command boundary.
15511553
* We have to do this before WriteBuffer because we need to look at the
@@ -1568,7 +1570,10 @@ heap_update(Relation relation, ItemPointer otid, HeapTuple newtup,
15681570
ItemIdlp;
15691571
HeapTupleDataoldtup;
15701572
PageHeaderdp;
1571-
Bufferbuffer,newbuf;
1573+
Bufferbuffer,
1574+
newbuf;
1575+
boolneed_toast,
1576+
already_marked;
15721577
intresult;
15731578

15741579
/* increment access statistics */
@@ -1645,77 +1650,92 @@ heap_update(Relation relation, ItemPointer otid, HeapTuple newtup,
16451650
returnresult;
16461651
}
16471652

1648-
/*XXX order problems if not atomic assignment ??? */
1653+
/*Fill in OID and transaction status data for newtup */
16491654
newtup->t_data->t_oid=oldtup.t_data->t_oid;
16501655
TransactionIdStore(GetCurrentTransactionId(),&(newtup->t_data->t_xmin));
16511656
newtup->t_data->t_cmin=GetCurrentCommandId();
16521657
StoreInvalidTransactionId(&(newtup->t_data->t_xmax));
16531658
newtup->t_data->t_infomask &= ~(HEAP_XACT_MASK);
16541659
newtup->t_data->t_infomask |= (HEAP_XMAX_INVALID |HEAP_UPDATED);
16551660

1656-
#ifdefTUPLE_TOASTER_ACTIVE
1657-
/* ----------
1658-
* If this relation is enabled for toasting, let the toaster
1659-
* delete any no-longer-needed entries and create new ones to
1660-
* make the new tuple fit again. Also, if there are already-
1661-
* toasted values from some other relation, the toaster must
1662-
* fix them.
1663-
* ----------
1661+
/*
1662+
* If the toaster needs to be activated, OR if the new tuple will not
1663+
* fit on the same page as the old, then we need to release the context
1664+
* lock (but not the pin!) on the old tuple's buffer while we are off
1665+
* doing TOAST and/or table-file-extension work. We must mark the old
1666+
* tuple to show that it's already being updated, else other processes
1667+
* may try to update it themselves. To avoid second XLOG log record,
1668+
* we use xact mgr hook to unlock old tuple without reading log if xact
1669+
* will abort before update is logged. In the event of crash prio logging,
1670+
* TQUAL routines will see HEAP_XMAX_UNLOGGED flag...
1671+
*
1672+
* NOTE: this trick is useless currently but saved for future
1673+
* when we'll implement UNDO and will re-use transaction IDs
1674+
* after postmaster startup.
1675+
*
1676+
* We need to invoke the toaster if there are already any toasted values
1677+
* present, or if the new tuple is over-threshold.
16641678
*/
1665-
if (HeapTupleHasExtended(&oldtup)||
1666-
HeapTupleHasExtended(newtup)||
1667-
(MAXALIGN(newtup->t_len)>TOAST_TUPLE_THRESHOLD))
1668-
heap_tuple_toast_attrs(relation,newtup,&oldtup);
1669-
#endif
1679+
need_toast= (HeapTupleHasExtended(&oldtup)||
1680+
HeapTupleHasExtended(newtup)||
1681+
(MAXALIGN(newtup->t_len)>TOAST_TUPLE_THRESHOLD));
16701682

1671-
/* Find buffer for new tuple */
1672-
1673-
if ((unsigned)MAXALIGN(newtup->t_len) <=PageGetFreeSpace((Page)dp))
1674-
newbuf=buffer;
1675-
else
1683+
if (need_toast||
1684+
(unsigned)MAXALIGN(newtup->t_len)>PageGetFreeSpace((Page)dp))
16761685
{
1677-
/*
1678-
* We have to unlock old tuple buffer before extending table
1679-
* file but have to keep lock on the old tuple. To avoid second
1680-
* XLOG log record we use xact mngr hook to unlock old tuple
1681-
* without reading log if xact will abort before update is logged.
1682-
* In the event of crash prio logging, TQUAL routines will see
1683-
* HEAP_XMAX_UNLOGGED flag...
1684-
*
1685-
* NOTE: this trick is useless currently but saved for future
1686-
* when we'll implement UNDO and will re-use transaction IDs
1687-
* after postmaster startup.
1688-
*/
16891686
_locked_tuple_.node=relation->rd_node;
16901687
_locked_tuple_.tid=oldtup.t_self;
16911688
XactPushRollback(_heap_unlock_tuple, (void*)&_locked_tuple_);
16921689

1693-
TransactionIdStore(GetCurrentTransactionId(),&(oldtup.t_data->t_xmax));
1690+
TransactionIdStore(GetCurrentTransactionId(),
1691+
&(oldtup.t_data->t_xmax));
16941692
oldtup.t_data->t_cmax=GetCurrentCommandId();
16951693
oldtup.t_data->t_infomask &= ~(HEAP_XMAX_COMMITTED |
1696-
HEAP_XMAX_INVALID |HEAP_MARKED_FOR_UPDATE);
1694+
HEAP_XMAX_INVALID |
1695+
HEAP_MARKED_FOR_UPDATE);
16971696
oldtup.t_data->t_infomask |=HEAP_XMAX_UNLOGGED;
1697+
already_marked= true;
16981698
LockBuffer(buffer,BUFFER_LOCK_UNLOCK);
1699-
newbuf=RelationGetBufferForTuple(relation,newtup->t_len);
1699+
1700+
/* Let the toaster do its thing */
1701+
if (need_toast)
1702+
heap_tuple_toast_attrs(relation,newtup,&oldtup);
1703+
1704+
/* Now, do we need a new page for the tuple, or not? */
1705+
if ((unsigned)MAXALIGN(newtup->t_len) <=PageGetFreeSpace((Page)dp))
1706+
newbuf=buffer;
1707+
else
1708+
newbuf=RelationGetBufferForTuple(relation,newtup->t_len);
1709+
1710+
/* Re-acquire the lock on the old tuple's page. */
17001711
/* this seems to be deadlock free... */
17011712
LockBuffer(buffer,BUFFER_LOCK_EXCLUSIVE);
17021713
}
1714+
else
1715+
{
1716+
/* No TOAST work needed, and it'll fit on same page */
1717+
already_marked= false;
1718+
newbuf=buffer;
1719+
}
17031720

17041721
/* NO ELOG(ERROR) from here till changes are logged */
17051722
START_CRIT_SECTION();
17061723

17071724
RelationPutHeapTuple(relation,newbuf,newtup);/* insert new tuple */
1708-
if (buffer==newbuf)
1725+
1726+
if (already_marked)
17091727
{
1710-
TransactionIdStore(GetCurrentTransactionId(),&(oldtup.t_data->t_xmax));
1711-
oldtup.t_data->t_cmax=GetCurrentCommandId();
1712-
oldtup.t_data->t_infomask &= ~(HEAP_XMAX_COMMITTED |
1713-
HEAP_XMAX_INVALID |HEAP_MARKED_FOR_UPDATE);
1728+
oldtup.t_data->t_infomask &= ~HEAP_XMAX_UNLOGGED;
1729+
XactPopRollback();
17141730
}
17151731
else
17161732
{
1717-
oldtup.t_data->t_infomask &= ~HEAP_XMAX_UNLOGGED;
1718-
XactPopRollback();
1733+
TransactionIdStore(GetCurrentTransactionId(),
1734+
&(oldtup.t_data->t_xmax));
1735+
oldtup.t_data->t_cmax=GetCurrentCommandId();
1736+
oldtup.t_data->t_infomask &= ~(HEAP_XMAX_COMMITTED |
1737+
HEAP_XMAX_INVALID |
1738+
HEAP_MARKED_FOR_UPDATE);
17191739
}
17201740

17211741
/* record address of new tuple in t_ctid of old one */
@@ -1724,7 +1744,7 @@ heap_update(Relation relation, ItemPointer otid, HeapTuple newtup,
17241744
/* XLOG stuff */
17251745
{
17261746
XLogRecPtrrecptr=log_heap_update(relation,buffer,oldtup.t_self,
1727-
newbuf,newtup, false);
1747+
newbuf,newtup, false);
17281748

17291749
if (newbuf!=buffer)
17301750
{
@@ -1734,6 +1754,7 @@ heap_update(Relation relation, ItemPointer otid, HeapTuple newtup,
17341754
PageSetLSN(BufferGetPage(buffer),recptr);
17351755
PageSetSUI(BufferGetPage(buffer),ThisStartUpID);
17361756
}
1757+
17371758
END_CRIT_SECTION();
17381759

17391760
if (newbuf!=buffer)

‎src/backend/access/heap/tuptoaster.c

Lines changed: 6 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/access/heap/tuptoaster.c,v 1.13 2000/10/23 23:42:04 tgl Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/access/heap/tuptoaster.c,v 1.14 2001/01/15 05:29:19 tgl Exp $
1212
*
1313
*
1414
* INTERFACE ROUTINES
@@ -197,10 +197,12 @@ toast_delete(Relation rel, HeapTuple oldtup)
197197
*/
198198
for (i=0;i<numAttrs;i++)
199199
{
200-
value=heap_getattr(oldtup,i+1,tupleDesc,&isnull);
201-
if (!isnull&&att[i]->attlen==-1)
202-
if (VARATT_IS_EXTERNAL(value))
200+
if (att[i]->attlen==-1)
201+
{
202+
value=heap_getattr(oldtup,i+1,tupleDesc,&isnull);
203+
if (!isnull&&VARATT_IS_EXTERNAL(value))
203204
toast_delete_datum(rel,value);
205+
}
204206
}
205207
}
206208

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