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Patch from Andreas: when CREATE TABLE is followed by CREATE INDEX 

before any tuples are loaded, preserve the default '1000 tuples' table
size estimate.
This commit is contained in:
Tom Lane 1999-05-26 22:57:39 +00:00
parent 8eb18d874e
commit 7c8beefd5e
2 changed files with 47 additions and 31 deletions
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11
src/backend/catalog/heap.c
View File

@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/catalog/heap.c,v 1.85 1999/05/25 16:08:03 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/catalog/heap.c,v 1.86 1999/05/26 22:57:39 tgl Exp $
*
*
* INTERFACE ROUTINES
@ -674,11 +674,10 @@ AddNewRelationTuple(Relation pg_class_desc,
* enough to discourage the optimizer from using nested-loop plans.
* With this hack, nested-loop plans will be preferred only after
* the table has been proven to be small by VACUUM or CREATE INDEX.
* (NOTE: if user does CREATE TABLE, then CREATE INDEX, then loads
* the table, he still loses until he vacuums, because CREATE INDEX
* will set reltuples to zero. Can't win 'em all. Maintaining the
* stats on-the-fly would solve the problem, but the overhead of that
* would likely cost more than it'd save.)
* Maintaining the stats on-the-fly would solve the problem more cleanly,
* but the overhead of that would likely cost more than it'd save.
* (NOTE: CREATE INDEX inserts the same bogus estimates if it finds the
* relation has 0 rows and pages. See index.c.)
* ----------------
*/
new_rel_reltup->relpages = 10; /* bogus estimates */

67
src/backend/catalog/index.c
View File

@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/catalog/index.c,v 1.75 1999/05/25 16:08:06 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/catalog/index.c,v 1.76 1999/05/26 22:57:39 tgl Exp $
*
*
* INTERFACE ROUTINES
@ -1291,7 +1291,6 @@ UpdateStats(Oid relid, long reltuples, bool hasindex)
if (!RelationIsValid(pg_class))
elog(ERROR, "UpdateStats: could not open RELATION relation");
if (!IsBootstrapProcessingMode())
{
tuple = SearchSysCacheTupleCopy(RELOID,
@ -1320,34 +1319,48 @@ UpdateStats(Oid relid, long reltuples, bool hasindex)
}
/* ----------------
* update statistics
* Figure values to insert.
*
* If we found zero tuples in the scan, do NOT believe it; instead put
* a bogus estimate into the statistics fields. Otherwise, the common
* pattern "CREATE TABLE; CREATE INDEX; insert data" leaves the table
* with zero size statistics until a VACUUM is done. The optimizer will
* generate very bad plans if the stats claim the table is empty when
* it is actually sizable. See also CREATE TABLE in heap.c.
* ----------------
*/
relpages = RelationGetNumberOfBlocks(whichRel);
if (reltuples == 0)
{
if (relpages == 0)
{
/* Bogus defaults for a virgin table, same as heap.c */
reltuples = 1000;
relpages = 10;
}
else if (whichRel->rd_rel->relkind == RELKIND_INDEX && relpages <= 2)
{
/* Empty index, leave bogus defaults in place */
reltuples = 1000;
}
else
reltuples = relpages * NTUPLES_PER_PAGE(whichRel->rd_rel->relnatts);
}
/*
* We shouldn't have to do this, but we do... Modify the reldesc in
* place with the new values so that the cache contains the latest
* copy.
*/
whichRel->rd_rel->relhasindex = hasindex;
whichRel->rd_rel->relpages = relpages;
whichRel->rd_rel->reltuples = reltuples;
for (i = 0; i < Natts_pg_class; i++)
{
nulls[i] = heap_attisnull(tuple, i + 1) ? 'n' : ' ';
replace[i] = ' ';
values[i] = (Datum) NULL;
}
/*
* If reltuples wasn't supplied take an educated guess.
/* ----------------
* Update statistics in pg_class.
* ----------------
*/
if (reltuples == 0)
reltuples = relpages * NTUPLES_PER_PAGE(whichRel->rd_rel->relnatts);
if (IsBootstrapProcessingMode())
{
@ -1363,7 +1376,15 @@ UpdateStats(Oid relid, long reltuples, bool hasindex)
}
else
{
/* during normal processing, work harder */
/* During normal processing, must work harder. */
for (i = 0; i < Natts_pg_class; i++)
{
nulls[i] = heap_attisnull(tuple, i + 1) ? 'n' : ' ';
replace[i] = ' ';
values[i] = (Datum) NULL;
}
replace[Anum_pg_class_relpages - 1] = 'r';
values[Anum_pg_class_relpages - 1] = (Datum) relpages;
replace[Anum_pg_class_reltuples - 1] = 'r';
@ -1438,12 +1459,10 @@ DefaultBuild(Relation heapRelation,
char *nullv;
long reltuples,
indtuples;
#ifndef OMIT_PARTIAL_INDEX
ExprContext *econtext;
TupleTable tupleTable;
TupleTableSlot *slot;
#endif
Node *predicate;
Node *oldPred;
@ -1524,13 +1543,13 @@ DefaultBuild(Relation heapRelation,
{
reltuples++;
#ifndef OMIT_PARTIAL_INDEX
/*
* If oldPred != NULL, this is an EXTEND INDEX command, so skip
* this tuple if it was already in the existing partial index
*/
if (oldPred != NULL)
{
#ifndef OMIT_PARTIAL_INDEX
/* SetSlotContents(slot, heapTuple); */
slot->val = heapTuple;
if (ExecQual((List *) oldPred, econtext) == true)
@ -1538,7 +1557,6 @@ DefaultBuild(Relation heapRelation,
indtuples++;
continue;
}
#endif /* OMIT_PARTIAL_INDEX */
}
/*
@ -1547,13 +1565,12 @@ DefaultBuild(Relation heapRelation,
*/
if (predicate != NULL)
{
#ifndef OMIT_PARTIAL_INDEX
/* SetSlotContents(slot, heapTuple); */
slot->val = heapTuple;
if (ExecQual((List *) predicate, econtext) == false)
continue;
#endif /* OMIT_PARTIAL_INDEX */
}
#endif /* OMIT_PARTIAL_INDEX */
indtuples++;
@ -1586,12 +1603,12 @@ DefaultBuild(Relation heapRelation,
heap_endscan(scan);
#ifndef OMIT_PARTIAL_INDEX
if (predicate != NULL || oldPred != NULL)
{
#ifndef OMIT_PARTIAL_INDEX
ExecDestroyTupleTable(tupleTable, false);
#endif /* OMIT_PARTIAL_INDEX */
}
#endif /* OMIT_PARTIAL_INDEX */
pfree(nullv);
pfree(datum);