From 1e07a94435237462f63685c327d13e023549a10c Mon Sep 17 00:00:00 2001
From: Andres Freund <andres@anarazel.de>
Date: Thu, 16 Jun 2016 14:49:00 -0700
Subject: [PATCH] Use cached comparator in ShardIntervalsOverlap().

By far the most expensive part of ShardIntervalsOverlap() is computing
the function to use to determine overlap. Luckily we already have that
computed and cached.

The plan time for the query in issue #607 goes from 8764 ms to 2889 ms
with this change.
---
 src/backend/distributed/planner/multi_physical_planner.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/src/backend/distributed/planner/multi_physical_planner.c b/src/backend/distributed/planner/multi_physical_planner.c
index f714aa3c3..3b800f09f 100644
--- a/src/backend/distributed/planner/multi_physical_planner.c
+++ b/src/backend/distributed/planner/multi_physical_planner.c
@@ -3601,17 +3601,16 @@ FragmentInterval(RangeTableFragment *fragment)
 bool
 ShardIntervalsOverlap(ShardInterval *firstInterval, ShardInterval *secondInterval)
 {
-	Oid typeId = InvalidOid;
-	FmgrInfo *comparisonFunction = NULL;
 	bool nonOverlap = false;
+	DistTableCacheEntry *intervalRelation =
+		DistributedTableCacheEntry(firstInterval->relationId);
+	FmgrInfo *comparisonFunction = intervalRelation->shardIntervalCompareFunction;
 
 	Datum firstMin = 0;
 	Datum firstMax = 0;
 	Datum secondMin = 0;
 	Datum secondMax = 0;
 
-	typeId = firstInterval->valueTypeId;
-	comparisonFunction = GetFunctionInfo(typeId, BTREE_AM_OID, BTORDER_PROC);
 
 	firstMin = firstInterval->minValue;
 	firstMax = firstInterval->maxValue;