diff --git a/src/backend/access/nbtree/nbtinsert.c b/src/backend/access/nbtree/nbtinsert.c
index 98a46ab585791ecd579de55396834955553424a3..e229083b8a1b8f86c8f14fb8a3da3477af4d441a 100644
--- a/src/backend/access/nbtree/nbtinsert.c
+++ b/src/backend/access/nbtree/nbtinsert.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/access/nbtree/nbtinsert.c,v 1.151 2007/02/08 13:52:55 alvherre Exp $
+ * $PostgreSQL: pgsql/src/backend/access/nbtree/nbtinsert.c,v 1.152 2007/02/21 20:02:17 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@@ -29,6 +29,10 @@ typedef struct
int fillfactor; /* needed when splitting rightmost page */
bool is_leaf; /* T if splitting a leaf page */
bool is_rightmost; /* T if splitting a rightmost page */
+ OffsetNumber newitemoff; /* where the new item is to be inserted */
+ int leftspace; /* space available for items on left page */
+ int rightspace; /* space available for items on right page */
+ int olddataitemstotal; /* space taken by old items */
bool have_split; /* found a valid split? */
@@ -57,9 +61,9 @@ static OffsetNumber _bt_findsplitloc(Relation rel, Page page,
OffsetNumber newitemoff,
Size newitemsz,
bool *newitemonleft);
-static void _bt_checksplitloc(FindSplitData *state, OffsetNumber firstright,
- int leftfree, int rightfree,
- bool newitemonleft, Size firstrightitemsz);
+static void _bt_checksplitloc(FindSplitData *state,
+ OffsetNumber firstoldonright, bool newitemonleft,
+ int dataitemstoleft, Size firstoldonrightsz);
static void _bt_pgaddtup(Relation rel, Page page,
Size itemsize, IndexTuple itup,
OffsetNumber itup_off, const char *where);
@@ -1101,13 +1105,31 @@ _bt_findsplitloc(Relation rel,
int leftspace,
rightspace,
goodenough,
- dataitemtotal,
- dataitemstoleft;
+ olddataitemstotal,
+ olddataitemstoleft;
+ bool goodenoughfound;
opaque = (BTPageOpaque) PageGetSpecialPointer(page);
/* Passed-in newitemsz is MAXALIGNED but does not include line pointer */
newitemsz += sizeof(ItemIdData);
+
+ /* Total free space available on a btree page, after fixed overhead */
+ leftspace = rightspace =
+ PageGetPageSize(page) - SizeOfPageHeaderData -
+ MAXALIGN(sizeof(BTPageOpaqueData));
+
+ /* The right page will have the same high key as the old page */
+ if (!P_RIGHTMOST(opaque))
+ {
+ itemid = PageGetItemId(page, P_HIKEY);
+ rightspace -= (int) (MAXALIGN(ItemIdGetLength(itemid)) +
+ sizeof(ItemIdData));
+ }
+
+ /* Count up total space in data items without actually scanning 'em */
+ olddataitemstotal = rightspace - (int) PageGetExactFreeSpace(page);
+
state.newitemsz = newitemsz;
state.is_leaf = P_ISLEAF(opaque);
state.is_rightmost = P_RIGHTMOST(opaque);
@@ -1120,11 +1142,10 @@ _bt_findsplitloc(Relation rel,
state.newitemonleft = false; /* these just to keep compiler quiet */
state.firstright = 0;
state.best_delta = 0;
-
- /* Total free space available on a btree page, after fixed overhead */
- leftspace = rightspace =
- PageGetPageSize(page) - SizeOfPageHeaderData -
- MAXALIGN(sizeof(BTPageOpaqueData));
+ state.leftspace = leftspace;
+ state.rightspace = rightspace;
+ state.olddataitemstotal = olddataitemstotal;
+ state.newitemoff = newitemoff;
/*
* Finding the best possible split would require checking all the possible
@@ -1137,74 +1158,60 @@ _bt_findsplitloc(Relation rel,
*/
goodenough = leftspace / 16;
- /* The right page will have the same high key as the old page */
- if (!P_RIGHTMOST(opaque))
- {
- itemid = PageGetItemId(page, P_HIKEY);
- rightspace -= (int) (MAXALIGN(ItemIdGetLength(itemid)) +
- sizeof(ItemIdData));
- }
-
- /* Count up total space in data items without actually scanning 'em */
- dataitemtotal = rightspace - (int) PageGetFreeSpace(page);
-
/*
* Scan through the data items and calculate space usage for a split at
* each possible position.
*/
- dataitemstoleft = 0;
+ olddataitemstoleft = 0;
+ goodenoughfound = false;
maxoff = PageGetMaxOffsetNumber(page);
-
+
for (offnum = P_FIRSTDATAKEY(opaque);
offnum <= maxoff;
offnum = OffsetNumberNext(offnum))
{
Size itemsz;
- int leftfree,
- rightfree;
itemid = PageGetItemId(page, offnum);
itemsz = MAXALIGN(ItemIdGetLength(itemid)) + sizeof(ItemIdData);
- /*
- * We have to allow for the current item becoming the high key of the
- * left page; therefore it counts against left space as well as right
- * space.
- */
- leftfree = leftspace - dataitemstoleft - (int) itemsz;
- rightfree = rightspace - (dataitemtotal - dataitemstoleft);
-
/*
* Will the new item go to left or right of split?
*/
if (offnum > newitemoff)
- _bt_checksplitloc(&state, offnum, leftfree, rightfree,
- true, itemsz);
+ _bt_checksplitloc(&state, offnum, true,
+ olddataitemstoleft, itemsz);
+
else if (offnum < newitemoff)
- _bt_checksplitloc(&state, offnum, leftfree, rightfree,
- false, itemsz);
+ _bt_checksplitloc(&state, offnum, false,
+ olddataitemstoleft, itemsz);
else
{
/* need to try it both ways! */
- _bt_checksplitloc(&state, offnum, leftfree, rightfree,
- true, itemsz);
- /*
- * Here we are contemplating newitem as first on right. In this
- * case it, not the current item, will become the high key of the
- * left page, and so we have to correct the allowance made above.
- */
- leftfree += (int) itemsz - (int) newitemsz;
- _bt_checksplitloc(&state, offnum, leftfree, rightfree,
- false, newitemsz);
+ _bt_checksplitloc(&state, offnum, true,
+ olddataitemstoleft, itemsz);
+
+ _bt_checksplitloc(&state, offnum, false,
+ olddataitemstoleft, itemsz);
}
/* Abort scan once we find a good-enough choice */
if (state.have_split && state.best_delta <= goodenough)
+ {
+ goodenoughfound = true;
break;
+ }
- dataitemstoleft += itemsz;
+ olddataitemstoleft += itemsz;
}
+ /* If the new item goes as the last item, check for splitting so that
+ * all the old items go to the left page and the new item goes to the
+ * right page.
+ */
+ if (newitemoff > maxoff && !goodenoughfound)
+ _bt_checksplitloc(&state, newitemoff, false, olddataitemstotal, 0);
+
/*
* I believe it is not possible to fail to find a feasible split, but just
* in case ...
@@ -1220,15 +1227,50 @@ _bt_findsplitloc(Relation rel,
/*
* Subroutine to analyze a particular possible split choice (ie, firstright
* and newitemonleft settings), and record the best split so far in *state.
+ *
+ * firstoldonright is the offset of the first item on the original page
+ * that goes to the right page, and firstoldonrightsz is the size of that
+ * tuple. firstoldonright can be > max offset, which means that all the old
+ * items go to the left page and only the new item goes to the right page.
+ * In that case, firstoldonrightsz is not used.
+ *
+ * olddataitemstoleft is the total size of all old items to the left of
+ * firstoldonright.
*/
static void
-_bt_checksplitloc(FindSplitData *state, OffsetNumber firstright,
- int leftfree, int rightfree,
- bool newitemonleft, Size firstrightitemsz)
+_bt_checksplitloc(FindSplitData *state,
+ OffsetNumber firstoldonright,
+ bool newitemonleft,
+ int olddataitemstoleft,
+ Size firstoldonrightsz)
{
+ int leftfree,
+ rightfree;
+ Size firstrightitemsz;
+ bool newitemisfirstonright;
+
+ /* Is the new item going to be the first item on the right page? */
+ newitemisfirstonright = (firstoldonright == state->newitemoff
+ && !newitemonleft);
+
+ if(newitemisfirstonright)
+ firstrightitemsz = state->newitemsz;
+ else
+ firstrightitemsz = firstoldonrightsz;
+
+ /* Account for all the old tuples */
+ leftfree = state->leftspace - olddataitemstoleft;
+ rightfree = state->rightspace -
+ (state->olddataitemstotal - olddataitemstoleft);
+
/*
- * Account for the new item on whichever side it is to be put.
+ * The first item on the right page becomes the high key of the
+ * left page; therefore it counts against left space as well as right
+ * space.
*/
+ leftfree -= firstrightitemsz;
+
+ /* account for the new item */
if (newitemonleft)
leftfree -= (int) state->newitemsz;
else
@@ -1270,7 +1312,7 @@ _bt_checksplitloc(FindSplitData *state, OffsetNumber firstright,
{
state->have_split = true;
state->newitemonleft = newitemonleft;
- state->firstright = firstright;
+ state->firstright = firstoldonright;
state->best_delta = delta;
}
}
diff --git a/src/backend/storage/page/bufpage.c b/src/backend/storage/page/bufpage.c
index 2e5c7c412bff264d6087abce6d8404320936e56e..8299f550d6e02303db13c289565832367003758e 100644
--- a/src/backend/storage/page/bufpage.c
+++ b/src/backend/storage/page/bufpage.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/storage/page/bufpage.c,v 1.70 2007/01/05 22:19:38 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/storage/page/bufpage.c,v 1.71 2007/02/21 20:02:17 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@@ -418,7 +418,8 @@ PageRepairFragmentation(Page page, OffsetNumber *unused)
/*
* PageGetFreeSpace
- * Returns the size of the free (allocatable) space on a page.
+ * Returns the size of the free (allocatable) space on a page,
+ * deducted by the space needed for a new line pointer.
*/
Size
PageGetFreeSpace(Page page)
@@ -434,7 +435,26 @@ PageGetFreeSpace(Page page)
if (space < (int) sizeof(ItemIdData))
return 0;
- space -= sizeof(ItemIdData); /* XXX not always appropriate */
+ space -= sizeof(ItemIdData);
+
+ return (Size) space;
+}
+
+/*
+ * PageGetExactFreeSpace
+ * Returns the size of the free (allocatable) space on a page.
+ */
+Size
+PageGetExactFreeSpace(Page page)
+{
+ int space;
+
+ /*
+ * Use signed arithmetic here so that we behave sensibly if pd_lower >
+ * pd_upper.
+ */
+ space = (int) ((PageHeader) page)->pd_upper -
+ (int) ((PageHeader) page)->pd_lower;
return (Size) space;
}
diff --git a/src/include/storage/bufpage.h b/src/include/storage/bufpage.h
index abb51404a54855b71fb8bca100e06c3270e8c08f..44ab48c9b8f6d8daf33630067febcb3bf246c6bd 100644
--- a/src/include/storage/bufpage.h
+++ b/src/include/storage/bufpage.h
@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/storage/bufpage.h,v 1.70 2007/02/09 03:35:34 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/storage/bufpage.h,v 1.71 2007/02/21 20:02:17 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@@ -322,6 +322,7 @@ extern Page PageGetTempPage(Page page, Size specialSize);
extern void PageRestoreTempPage(Page tempPage, Page oldPage);
extern int PageRepairFragmentation(Page page, OffsetNumber *unused);
extern Size PageGetFreeSpace(Page page);
+extern Size PageGetExactFreeSpace(Page page);
extern void PageIndexTupleDelete(Page page, OffsetNumber offset);
extern void PageIndexMultiDelete(Page page, OffsetNumber *itemnos, int nitems);