From 0392ea5097e5d7b8068b64722a34b7b75791a8f5 Mon Sep 17 00:00:00 2001
From: Teodor Sigaev <teodor@sigaev.ru>
Date: Fri, 7 Sep 2007 17:04:26 +0000
Subject: [PATCH] Improve page split in rtree emulation. Now if splitted result
has big misalignement, then it tries to split page basing on distribution of
boxe's centers.
Per report from Dolafi, Tom <dolafit@janelia.hhmi.org>
Backpatch is needed, change doesn't affect on-disk storage.
---
src/backend/access/gist/gistproc.c | 79 +++++++++++++-----------------
1 file changed, 34 insertions(+), 45 deletions(-)
diff --git a/src/backend/access/gist/gistproc.c b/src/backend/access/gist/gistproc.c
index 19868a127e7..590be9133fb 100644
--- a/src/backend/access/gist/gistproc.c
+++ b/src/backend/access/gist/gistproc.c
@@ -10,7 +10,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/access/gist/gistproc.c,v 1.10 2007/01/05 22:19:22 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/access/gist/gistproc.c,v 1.11 2007/09/07 17:04:26 teodor Exp $
*
*-------------------------------------------------------------------------
*/
@@ -21,13 +21,6 @@
#include "utils/geo_decls.h"
-typedef struct
-{
- BOX *key;
- int pos;
-} KBsort;
-
-static int compare_KB(const void *a, const void *b);
static bool gist_box_leaf_consistent(BOX *key, BOX *query,
StrategyNumber strategy);
static double size_box(Datum dbox);
@@ -194,22 +187,6 @@ gist_box_penalty(PG_FUNCTION_ARGS)
PG_RETURN_POINTER(result);
}
-/*
- * qsort comparator for box areas
- */
-static int
-compare_KB(const void *a, const void *b)
-{
- BOX *abox = ((const KBsort *) a)->key;
- BOX *bbox = ((const KBsort *) b)->key;
- double sa = (abox->high.x - abox->low.x) * (abox->high.y - abox->low.y);
- double sb = (bbox->high.x - bbox->low.x) * (bbox->high.y - bbox->low.y);
-
- if (sa == sb)
- return 0;
- return (sa > sb) ? 1 : -1;
-}
-
static void
chooseLR(GIST_SPLITVEC *v,
OffsetNumber *list1, int nlist1, BOX *union1,
@@ -417,44 +394,56 @@ gist_box_picksplit(PG_FUNCTION_ARGS)
ADDLIST(listT, unionT, posT, i);
}
- /* bad disposition, sort by ascending and resplit */
- if ((posR == 0 || posL == 0) && (posT == 0 || posB == 0))
+#define LIMIT_RATIO 0.1
+#define _IS_BADRATIO(x,y) ( (y) == 0 || (float)(x)/(float)(y) < LIMIT_RATIO )
+#define IS_BADRATIO(x,y) ( _IS_BADRATIO((x),(y)) || _IS_BADRATIO((y),(x)) )
+ /* bad disposition, try to split by centers of boxes */
+ if ( IS_BADRATIO(posR, posL) && IS_BADRATIO(posT, posB) )
{
- KBsort *arr = (KBsort *) palloc(sizeof(KBsort) * maxoff);
+ double avgCenterX=0.0, avgCenterY=0.0;
+ double CenterX, CenterY;
- posL = posR = posB = posT = 0;
for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
{
- arr[i - 1].key = DatumGetBoxP(entryvec->vector[i].key);
- arr[i - 1].pos = i;
+ cur = DatumGetBoxP(entryvec->vector[i].key);
+ avgCenterX += ((double)cur->high.x + (double)cur->low.x)/2.0;
+ avgCenterY += ((double)cur->high.y + (double)cur->low.y)/2.0;
}
- qsort(arr, maxoff, sizeof(KBsort), compare_KB);
+
+ avgCenterX /= maxoff;
+ avgCenterY /= maxoff;
+
+ posL = posR = posB = posT = 0;
for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
{
- cur = arr[i - 1].key;
- if (cur->low.x - pageunion.low.x < pageunion.high.x - cur->high.x)
- ADDLIST(listL, unionL, posL, arr[i - 1].pos);
- else if (cur->low.x - pageunion.low.x == pageunion.high.x - cur->high.x)
+ cur = DatumGetBoxP(entryvec->vector[i].key);
+
+ CenterX = ((double)cur->high.x + (double)cur->low.x)/2.0;
+ CenterY = ((double)cur->high.y + (double)cur->low.y)/2.0;
+
+ if (CenterX < avgCenterX)
+ ADDLIST(listL, unionL, posL, i);
+ else if (CenterX == avgCenterX)
{
if (posL > posR)
- ADDLIST(listR, unionR, posR, arr[i - 1].pos);
+ ADDLIST(listR, unionR, posR, i);
else
- ADDLIST(listL, unionL, posL, arr[i - 1].pos);
+ ADDLIST(listL, unionL, posL, i);
}
else
- ADDLIST(listR, unionR, posR, arr[i - 1].pos);
+ ADDLIST(listR, unionR, posR, i);
- if (cur->low.y - pageunion.low.y < pageunion.high.y - cur->high.y)
- ADDLIST(listB, unionB, posB, arr[i - 1].pos);
- else if (cur->low.y - pageunion.low.y == pageunion.high.y - cur->high.y)
+ if (CenterY < avgCenterY)
+ ADDLIST(listB, unionB, posB, i);
+ else if (CenterY == avgCenterY)
{
if (posB > posT)
- ADDLIST(listT, unionT, posT, arr[i - 1].pos);
+ ADDLIST(listT, unionT, posT, i);
else
- ADDLIST(listB, unionB, posB, arr[i - 1].pos);
+ ADDLIST(listB, unionB, posB, i);
}
- else
- ADDLIST(listT, unionT, posT, arr[i - 1].pos);
+ else
+ ADDLIST(listT, unionT, posT, i);
}
}
--
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