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Combine cmin and cmax fields of HeapTupleHeaders into a single field, by

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keeping private state in each backend that has inserted and deleted the same
tuple during its current top-level transaction.  This is sufficient since
there is no need to be able to determine the cmin/cmax from any other
transaction.  This gets us back down to 23-byte headers, removing a penalty
paid in 8.0 to support subtransactions.  Patch by Heikki Linnakangas, with
minor revisions by moi, following a design hashed out awhile back on the
pghackers list.
This commit is contained in:
Tom Lane
2007-02-09 03:35:35 +00:00
parent acb3416686
commit c398300330
21 changed files with 799 additions and 127 deletions
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36
src/backend/access/heap/heapam.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/heap/heapam.c,v 1.227 2007/02/05 04:22:18 tgl Exp $
* $PostgreSQL: pgsql/src/backend/access/heap/heapam.c,v 1.228 2007/02/09 03:35:33 tgl Exp $
*
*
* INTERFACE ROUTINES
@ -1407,8 +1407,7 @@ heap_insert(Relation relation, HeapTuple tup, CommandId cid,
tup->t_data->t_infomask |= HEAP_XMAX_INVALID;
HeapTupleHeaderSetXmin(tup->t_data, xid);
HeapTupleHeaderSetCmin(tup->t_data, cid);
HeapTupleHeaderSetXmax(tup->t_data, 0); /* zero out Datum fields */
HeapTupleHeaderSetCmax(tup->t_data, 0); /* for cleanliness */
HeapTupleHeaderSetXmax(tup->t_data, 0); /* for cleanliness */
tup->t_tableOid = RelationGetRelid(relation);
/*
@ -1585,6 +1584,7 @@ heap_delete(Relation relation, ItemPointer tid,
PageHeader dp;
Buffer buffer;
bool have_tuple_lock = false;
bool iscombo;
Assert(ItemPointerIsValid(tid));
@ -1724,6 +1724,9 @@ l1:
return result;
}
/* replace cid with a combo cid if necessary */
HeapTupleHeaderAdjustCmax(tp.t_data, &cid, &iscombo);
START_CRIT_SECTION();
/* store transaction information of xact deleting the tuple */
@ -1733,7 +1736,7 @@ l1:
HEAP_IS_LOCKED |
HEAP_MOVED);
HeapTupleHeaderSetXmax(tp.t_data, xid);
HeapTupleHeaderSetCmax(tp.t_data, cid);
HeapTupleHeaderSetCmax(tp.t_data, cid, iscombo);
/* Make sure there is no forward chain link in t_ctid */
tp.t_data->t_ctid = tp.t_self;
@ -1893,6 +1896,7 @@ heap_update(Relation relation, ItemPointer otid, HeapTuple newtup,
Size newtupsize,
pagefree;
bool have_tuple_lock = false;
bool iscombo;
Assert(ItemPointerIsValid(otid));
@ -2058,8 +2062,13 @@ l2:
newtup->t_data->t_infomask |= (HEAP_XMAX_INVALID | HEAP_UPDATED);
HeapTupleHeaderSetXmin(newtup->t_data, xid);
HeapTupleHeaderSetCmin(newtup->t_data, cid);
HeapTupleHeaderSetXmax(newtup->t_data, 0); /* zero out Datum fields */
HeapTupleHeaderSetCmax(newtup->t_data, 0); /* for cleanliness */
HeapTupleHeaderSetXmax(newtup->t_data, 0); /* for cleanliness */
/*
* Replace cid with a combo cid if necessary. Note that we already put
* the plain cid into the new tuple.
*/
HeapTupleHeaderAdjustCmax(oldtup.t_data, &cid, &iscombo);
/*
* If the toaster needs to be activated, OR if the new tuple will not fit
@ -2088,7 +2097,7 @@ l2:
HEAP_IS_LOCKED |
HEAP_MOVED);
HeapTupleHeaderSetXmax(oldtup.t_data, xid);
HeapTupleHeaderSetCmax(oldtup.t_data, cid);
HeapTupleHeaderSetCmax(oldtup.t_data, cid, iscombo);
/* temporarily make it look not-updated */
oldtup.t_data->t_ctid = oldtup.t_self;
already_marked = true;
@ -2183,7 +2192,7 @@ l2:
HEAP_IS_LOCKED |
HEAP_MOVED);
HeapTupleHeaderSetXmax(oldtup.t_data, xid);
HeapTupleHeaderSetCmax(oldtup.t_data, cid);
HeapTupleHeaderSetCmax(oldtup.t_data, cid, iscombo);
}
/* record address of new tuple in t_ctid of old one */
@ -2687,12 +2696,11 @@ l3:
/*
* Store transaction information of xact locking the tuple.
*
* Note: our CID is meaningless if storing a MultiXactId, but no harm in
* storing it anyway.
* Note: Cmax is meaningless in this context, so don't set it; this
* avoids possibly generating a useless combo CID.
*/
tuple->t_data->t_infomask = new_infomask;
HeapTupleHeaderSetXmax(tuple->t_data, xid);
HeapTupleHeaderSetCmax(tuple->t_data, cid);
/* Make sure there is no forward chain link in t_ctid */
tuple->t_data->t_ctid = *tid;
@ -3443,7 +3451,7 @@ heap_xlog_delete(XLogRecPtr lsn, XLogRecord *record)
HEAP_IS_LOCKED |
HEAP_MOVED);
HeapTupleHeaderSetXmax(htup, record->xl_xid);
HeapTupleHeaderSetCmax(htup, FirstCommandId);
HeapTupleHeaderSetCmax(htup, FirstCommandId, false);
/* Make sure there is no forward chain link in t_ctid */
htup->t_ctid = xlrec->target.tid;
PageSetLSN(page, lsn);
@ -3608,7 +3616,7 @@ heap_xlog_update(XLogRecPtr lsn, XLogRecord *record, bool move)
HEAP_IS_LOCKED |
HEAP_MOVED);
HeapTupleHeaderSetXmax(htup, record->xl_xid);
HeapTupleHeaderSetCmax(htup, FirstCommandId);
HeapTupleHeaderSetCmax(htup, FirstCommandId, false);
/* Set forward chain link in t_ctid */
htup->t_ctid = xlrec->newtid;
}
@ -3761,7 +3769,7 @@ heap_xlog_lock(XLogRecPtr lsn, XLogRecord *record)
else
htup->t_infomask |= HEAP_XMAX_EXCL_LOCK;
HeapTupleHeaderSetXmax(htup, xlrec->locking_xid);
HeapTupleHeaderSetCmax(htup, FirstCommandId);
HeapTupleHeaderSetCmax(htup, FirstCommandId, false);
/* Make sure there is no forward chain link in t_ctid */
htup->t_ctid = xlrec->target.tid;
PageSetLSN(page, lsn);