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Improve performance of OverrideSearchPathMatchesCurrent().

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This function was initially coded on the assumption that it would not be
performance-critical, but that turns out to be wrong in workloads that
are heavily dependent on the speed of plpgsql functions.  Speed it up by
hard-coding the comparison rules, thereby avoiding palloc/pfree traffic
from creating and immediately freeing an OverrideSearchPath object.
Per report from Scott Marlowe.
This commit is contained in:
Tom Lane 2014-11-28 12:37:27 -05:00
parent e384ed6cde
commit 96d66bcfc6
1 changed files with 37 additions and 13 deletions
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50
src/backend/catalog/namespace.c
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@ -3145,20 +3145,44 @@ CopyOverrideSearchPath(OverrideSearchPath *path)
bool
OverrideSearchPathMatchesCurrent(OverrideSearchPath *path)
{
/* Easiest way to do this is GetOverrideSearchPath() and compare */
bool result;
OverrideSearchPath *cur;
ListCell *lc,
*lcp;
cur = GetOverrideSearchPath(CurrentMemoryContext);
if (path->addCatalog == cur->addCatalog &&
path->addTemp == cur->addTemp &&
equal(path->schemas, cur->schemas))
result = true;
else
result = false;
list_free(cur->schemas);
pfree(cur);
return result;
recomputeNamespacePath();
/* We scan down the activeSearchPath to see if it matches the input. */
lc = list_head(activeSearchPath);
/* If path->addTemp, first item should be my temp namespace. */
if (path->addTemp)
{
if (lc && lfirst_oid(lc) == myTempNamespace)
lc = lnext(lc);
else
return false;
}
/* If path->addCatalog, next item should be pg_catalog. */
if (path->addCatalog)
{
if (lc && lfirst_oid(lc) == PG_CATALOG_NAMESPACE)
lc = lnext(lc);
else
return false;
}
/* We should now be looking at the activeCreationNamespace. */
if (activeCreationNamespace != (lc ? lfirst_oid(lc) : InvalidOid))
return false;
/* The remainder of activeSearchPath should match path->schemas. */
foreach(lcp, path->schemas)
{
if (lc && lfirst_oid(lc) == lfirst_oid(lcp))
lc = lnext(lc);
else
return false;
}
if (lc)
return false;
return true;
}
/*