On Mon, Mar 23, 2015 at 12:33 PM, Tom Lane <[email protected]> wrote:
>
> =?UTF-8?Q?Fabr=C3=ADzio_de_Royes_Mello?= <[email protected]> writes:
> > On Fri, Mar 20, 2015 at 4:37 PM, Tom Lane <[email protected]> wrote:
> >>>> We could fix it by, say, having CheckConstraintFetch() sort the
> >>>> constraints by name after loading them.
>
> > Isn't better do this to read pg_constraint in name order?
>
> > - conscan = systable_beginscan(conrel, ConstraintRelidIndexId, true,
> > + conscan = systable_beginscan(conrel, ConstraintNameNspIndexId, true,
>
> Surely not. That would end up having to read *all* of pg_constraint, not
> only the rows applicable to the current relation.
>
Yeah... you're correct... we need the oid in the index.
> We could get the index to do the work for us if we changed it from an
> index on conrelid to one on conrelid, conname. However, seeing that that
> would bloat the index by a factor of sixteen, it hardly sounds like a
> free fix either.
>
But in this way we can save some cicles as Ashutosh complains... or am I
missing something?
> I really think that a quick application of qsort is the best-performing
> way to do this.
>
Something like the attached?
With current master:
fabrizio=# create table foo(a integer, b integer);
CREATE TABLE
fabrizio=# alter table foo add constraint aa check(a>0);
ALTER TABLE
fabrizio=# alter table foo add constraint bb check(b>0);
ALTER TABLE
fabrizio=# insert into foo values (0,0);
ERROR: new row for relation "foo" violates check constraint "bb"
DETAIL: Failing row contains (0, 0).
With the attached patch:
fabrizio=# create table foo(a integer, b integer);
CREATE TABLE
fabrizio=# alter table foo add constraint aa check(a>0);
ALTER TABLE
fabrizio=# alter table foo add constraint bb check(b>0);
ALTER TABLE
fabrizio=# insert into foo values (0,0);
ERROR: new row for relation "foo" violates check constraint "aa"
DETAIL: Failing row contains (0, 0).
Regards,
--
Fabrízio de Royes Mello
Consultoria/Coaching PostgreSQL
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diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index 1db4ba84..d072031 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -282,6 +282,7 @@ static OpClassCacheEnt *LookupOpclassInfo(Oid operatorClassOid,
StrategyNumber numSupport);
static void RelationCacheInitFileRemoveInDir(const char *tblspcpath);
static void unlink_initfile(const char *initfilename);
+static int constrcheck_cmp(const void *p1, const void *p2);
/*
@@ -3734,6 +3735,20 @@ CheckConstraintFetch(Relation relation)
if (found != ncheck)
elog(ERROR, "%d constraint record(s) missing for rel %s",
ncheck - found, RelationGetRelationName(relation));
+
+ qsort((void *) check, ncheck, sizeof(ConstrCheck), constrcheck_cmp);
+}
+
+/*
+ * ConstrCheck qsort/bsearch comparator.
+ */
+static int
+constrcheck_cmp(const void *p1, const void *p2)
+{
+ ConstrCheck c1 = *(ConstrCheck *) p1;
+ ConstrCheck c2 = *(ConstrCheck *) p2;
+
+ return strcmp(c1.ccname, c2.ccname);
}
/*
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