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Resurrect heap_deformtuple(), this time implemented as a singly nested

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loop over the fields instead of a loop around heap_getattr.  This is
considerably faster (O(N) instead of O(N^2)) when there are nulls or
varlena fields, since those prevent use of attcacheoff.  Replace loops
over heap_getattr with heap_deformtuple in situations where all or most
of the fields have to be fetched, such as printtup and tuptoaster.
Profiling done more than a year ago shows that this should be a nice
win for situations involving many-column tables.
This commit is contained in:
Tom Lane
2004-06-04 20:35:21 +00:00
parent af44cac6ef
commit 8f2ea8b7b5
8 changed files with 313 additions and 207 deletions
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25
src/backend/commands/tablecmds.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.109 2004/06/02 21:01:08 momjian Exp $
* $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.110 2004/06/04 20:35:21 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -2342,10 +2342,10 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap)
newslot = MakeTupleTableSlot();
ExecSetSlotDescriptor(newslot, newTupDesc, false);
/* Preallocate values/nulls arrays (+1 in case natts==0) */
/* Preallocate values/nulls arrays */
i = Max(newTupDesc->natts, oldTupDesc->natts);
values = (Datum *) palloc(i * sizeof(Datum) + 1);
nulls = (char *) palloc(i * sizeof(char) + 1);
values = (Datum *) palloc(i * sizeof(Datum));
nulls = (char *) palloc(i * sizeof(char));
memset(values, 0, i * sizeof(Datum));
memset(nulls, 'n', i * sizeof(char));
@ -2363,24 +2363,14 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap)
* Extract data from old tuple. We can force to null any
* columns that are deleted according to the new tuple.
*/
int natts = oldTupDesc->natts;
bool isNull;
int natts = newTupDesc->natts;
heap_deformtuple(tuple, oldTupDesc, values, nulls);
for (i = 0; i < natts; i++)
{
if (newTupDesc->attrs[i]->attisdropped)
nulls[i] = 'n';
else
{
values[i] = heap_getattr(tuple,
i + 1,
oldTupDesc,
&isNull);
if (isNull)
nulls[i] = 'n';
else
nulls[i] = ' ';
}
}
/*
@ -2393,6 +2383,7 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap)
foreach(l, tab->newvals)
{
NewColumnValue *ex = lfirst(l);
bool isNull;
values[ex->attnum - 1] = ExecEvalExpr(ex->exprstate,
econtext,