Hi all,
This small patch improves the performance of INSERT and UPDATE. By my
machine, these changes raised the performance about 5%~10% in pgbench.
Please take a benchmark in a reliable environment. Since I may forget
some required changes, I specify that this patch is experimental. But
note that all regression tests have passed.
Thanks,
--
Hiroki Kataoka <[EMAIL PROTECTED]>
diff -ru postgresql-cvs.orig/src/backend/storage/page/bufpage.c
postgresql-cvs/src/backend/storage/page/bufpage.c
--- postgresql-cvs.orig/src/backend/storage/page/bufpage.c 2005-06-15
16:53:00.000000000 +0900
+++ postgresql-cvs/src/backend/storage/page/bufpage.c 2005-07-14
07:41:11.000000000 +0900
@@ -42,6 +42,7 @@
p->pd_lower = SizeOfPageHeaderData;
p->pd_upper = pageSize - specialSize;
p->pd_special = pageSize - specialSize;
+ p->pd_insoff = FirstOffsetNumber;
PageSetPageSizeAndVersion(page, pageSize, PG_PAGE_LAYOUT_VERSION);
}
@@ -100,7 +101,7 @@
* If offsetNumber is valid and <= current max offset in the page,
* insert item into the array at that position by shuffling ItemId's
* down to make room.
- * If offsetNumber is not valid, then assign one by finding the first
+ * If offsetNumber is not valid, then assign one by finding the next
* one that is both unused and deallocated.
*
* !!! EREPORT(ERROR) IS DISALLOWED HERE !!!
@@ -120,6 +121,7 @@
OffsetNumber limit;
bool needshuffle = false;
bool overwritemode = (flags & OverwritePageMode) != 0;
+ bool findunusedlinp = false;
flags &= ~OverwritePageMode;
@@ -165,9 +167,15 @@
}
else
{
- /* offsetNumber was not passed in, so find a free slot */
- /* look for "recyclable" (unused & deallocated) ItemId */
- for (offsetNumber = 1; offsetNumber < limit; offsetNumber++)
+ /* offsetNumber was not passed in, try to use pd_insoff */
+ if (OffsetNumberIsValid(phdr->pd_insoff))
+ offsetNumber = phdr->pd_insoff;
+ else
+ offsetNumber = FirstOffsetNumber;
+
+ /* so find a free slot look for "recyclable" (unused &
deallocated) */
+ /* ItemId */
+ for (; offsetNumber < limit; offsetNumber++)
{
itemId = PageGetItemId(phdr, offsetNumber);
if (((itemId->lp_flags & LP_USED) == 0) &&
@@ -175,6 +183,8 @@
break;
}
/* if no free slot, we'll put it at limit (1st open slot) */
+
+ findunusedlinp = true;
}
if (offsetNumber > limit)
@@ -222,6 +232,8 @@
/* adjust page header */
phdr->pd_lower = (LocationIndex) lower;
phdr->pd_upper = (LocationIndex) upper;
+ if (findunusedlinp)
+ phdr->pd_insoff = OffsetNumberNext(offsetNumber);
return offsetNumber;
}
@@ -345,8 +357,13 @@
lp->lp_flags &= ~(LP_USED | LP_DELETE);
if (lp->lp_flags & LP_USED)
nused++;
- else if (unused)
- unused[i - nused] = (OffsetNumber) i;
+ else
+ {
+ if (i - nused == 0) /* check if it's first unused
line pointer */
+ ((PageHeader) page)->pd_insoff = (OffsetNumber)
i + 1;
+ if (unused)
+ unused[i - nused] = (OffsetNumber) i;
+ }
}
if (nused == 0)
diff -ru postgresql-cvs.orig/src/include/storage/bufpage.h
postgresql-cvs/src/include/storage/bufpage.h
--- postgresql-cvs.orig/src/include/storage/bufpage.h 2005-04-29
06:47:18.000000000 +0900
+++ postgresql-cvs/src/include/storage/bufpage.h 2005-07-14
06:57:03.000000000 +0900
@@ -125,6 +125,7 @@
LocationIndex pd_lower; /* offset to start of free space */
LocationIndex pd_upper; /* offset to end of free space */
LocationIndex pd_special; /* offset to start of special space */
+ OffsetNumber pd_insoff; /* offset number for next new item */
uint16 pd_pagesize_version;
ItemIdData pd_linp[1]; /* beginning of line pointer
array */
} PageHeaderData;
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