diff --git a/src/backend/access/hash/hashinsert.c b/src/backend/access/hash/hashinsert.c
index d9da5e1ee378769e79eb62fe83e56943ec76db98..ad93e81640b86489a2b118a9ea461cd72188e41e 100644
--- a/src/backend/access/hash/hashinsert.c
+++ b/src/backend/access/hash/hashinsert.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/access/hash/hashinsert.c,v 1.27 2003/08/04 02:39:57 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/access/hash/hashinsert.c,v 1.28 2003/09/01 20:26:34 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -155,7 +155,7 @@ _hash_insertonpg(Relation rel,
* page with enough room. allocate a new overflow page.
*/
do_expand = true;
- ovflbuf = _hash_addovflpage(rel, &metabuf, buf);
+ ovflbuf = _hash_addovflpage(rel, metabuf, buf);
_hash_relbuf(rel, buf, HASH_WRITE);
buf = ovflbuf;
page = BufferGetPage(buf);
@@ -186,18 +186,15 @@ _hash_insertonpg(Relation rel,
* access type just for a moment to allow greater accessibility to
* the metapage.
*/
- metap = (HashMetaPage) _hash_chgbufaccess(rel, &metabuf,
- HASH_READ, HASH_WRITE);
- metap->hashm_nkeys += 1;
- metap = (HashMetaPage) _hash_chgbufaccess(rel, &metabuf,
- HASH_WRITE, HASH_READ);
-
+ _hash_chgbufaccess(rel, metabuf, HASH_READ, HASH_WRITE);
+ metap->hashm_ntuples += 1;
+ _hash_chgbufaccess(rel, metabuf, HASH_WRITE, HASH_READ);
}
_hash_wrtbuf(rel, buf);
if (do_expand ||
- (metap->hashm_nkeys / (metap->hashm_maxbucket + 1))
+ (metap->hashm_ntuples / (metap->hashm_maxbucket + 1))
> metap->hashm_ffactor)
_hash_expandtable(rel, metabuf);
_hash_relbuf(rel, metabuf, HASH_READ);
diff --git a/src/backend/access/hash/hashovfl.c b/src/backend/access/hash/hashovfl.c
index 06233b817b733fd0ddca150181e7eed3ad577022..aa74c547da40e5d5c77d060a22d12e8f6b090901 100644
--- a/src/backend/access/hash/hashovfl.c
+++ b/src/backend/access/hash/hashovfl.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/access/hash/hashovfl.c,v 1.37 2003/08/04 02:39:57 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/access/hash/hashovfl.c,v 1.38 2003/09/01 20:26:34 tgl Exp $
*
* NOTES
* Overflow pages look like ordinary relation pages.
@@ -20,24 +20,73 @@
#include "access/hash.h"
-static OverflowPageAddress _hash_getovfladdr(Relation rel, Buffer *metabufp);
+static BlockNumber _hash_getovflpage(Relation rel, Buffer metabuf);
static uint32 _hash_firstfreebit(uint32 map);
+
+/*
+ * Convert overflow page bit number (its index in the free-page bitmaps)
+ * to block number within the index.
+ */
+static BlockNumber
+bitno_to_blkno(HashMetaPage metap, uint32 ovflbitnum)
+{
+ uint32 splitnum = metap->hashm_ovflpoint;
+ uint32 i;
+
+ /* Convert zero-based bitnumber to 1-based page number */
+ ovflbitnum += 1;
+
+ /* Determine the split number for this page (must be >= 1) */
+ for (i = 1;
+ i < splitnum && ovflbitnum > metap->hashm_spares[i];
+ i++)
+ /* loop */ ;
+
+ /*
+ * Convert to absolute page number by adding the number of bucket pages
+ * that exist before this split point.
+ */
+ return (BlockNumber) ((1 << i) + ovflbitnum);
+}
+
+/*
+ * Convert overflow page block number to bit number for free-page bitmap.
+ */
+static uint32
+blkno_to_bitno(HashMetaPage metap, BlockNumber ovflblkno)
+{
+ uint32 splitnum = metap->hashm_ovflpoint;
+ uint32 i;
+ uint32 bitnum;
+
+ /* Determine the split number containing this page */
+ for (i = 1; i <= splitnum; i++)
+ {
+ if (ovflblkno <= (BlockNumber) (1 << i))
+ break; /* oops */
+ bitnum = ovflblkno - (1 << i);
+ if (bitnum <= metap->hashm_spares[i])
+ return bitnum - 1; /* -1 to convert 1-based to 0-based */
+ }
+
+ elog(ERROR, "invalid overflow block number %u", ovflblkno);
+ return 0; /* keep compiler quiet */
+}
+
/*
* _hash_addovflpage
*
* Add an overflow page to the page currently pointed to by the buffer
* argument 'buf'.
*
- * *Metabufp has a read lock upon entering the function; buf has a
- * write lock.
- *
+ * metabuf has a read lock upon entering the function; buf has a
+ * write lock. The same is true on exit. The returned overflow page
+ * is write-locked.
*/
Buffer
-_hash_addovflpage(Relation rel, Buffer *metabufp, Buffer buf)
+_hash_addovflpage(Relation rel, Buffer metabuf, Buffer buf)
{
-
- OverflowPageAddress oaddr;
BlockNumber ovflblkno;
Buffer ovflbuf;
HashMetaPage metap;
@@ -52,17 +101,12 @@ _hash_addovflpage(Relation rel, Buffer *metabufp, Buffer buf)
pageopaque = (HashPageOpaque) PageGetSpecialPointer(page);
Assert(!BlockNumberIsValid(pageopaque->hasho_nextblkno));
- metap = (HashMetaPage) BufferGetPage(*metabufp);
+ metap = (HashMetaPage) BufferGetPage(metabuf);
_hash_checkpage((Page) metap, LH_META_PAGE);
/* allocate an empty overflow page */
- oaddr = _hash_getovfladdr(rel, metabufp);
- if (oaddr == InvalidOvflAddress)
- elog(ERROR, "_hash_getovfladdr failed");
- ovflblkno = OADDR_TO_BLKNO(OADDR_OF(SPLITNUM(oaddr), OPAGENUM(oaddr)));
- Assert(BlockNumberIsValid(ovflblkno));
+ ovflblkno = _hash_getovflpage(rel, metabuf);
ovflbuf = _hash_getbuf(rel, ovflblkno, HASH_WRITE);
- Assert(BufferIsValid(ovflbuf));
ovflpage = BufferGetPage(ovflbuf);
/* initialize the new overflow page */
@@ -71,7 +115,7 @@ _hash_addovflpage(Relation rel, Buffer *metabufp, Buffer buf)
ovflopaque->hasho_prevblkno = BufferGetBlockNumber(buf);
ovflopaque->hasho_nextblkno = InvalidBlockNumber;
ovflopaque->hasho_flag = LH_OVERFLOW_PAGE;
- ovflopaque->hasho_oaddr = oaddr;
+ ovflopaque->hasho_oaddr = 0;
ovflopaque->hasho_bucket = pageopaque->hasho_bucket;
_hash_wrtnorelbuf(ovflbuf);
@@ -82,191 +126,141 @@ _hash_addovflpage(Relation rel, Buffer *metabufp, Buffer buf)
}
/*
- * _hash_getovfladdr()
+ * _hash_getovflpage()
*
- * Find an available overflow page and return its address.
+ * Find an available overflow page and return its block number.
*
- * When we enter this function, we have a read lock on *metabufp which
+ * When we enter this function, we have a read lock on metabuf which
* we change to a write lock immediately. Before exiting, the write lock
* is exchanged for a read lock.
- *
*/
-static OverflowPageAddress
-_hash_getovfladdr(Relation rel, Buffer *metabufp)
+static BlockNumber
+_hash_getovflpage(Relation rel, Buffer metabuf)
{
HashMetaPage metap;
Buffer mapbuf = 0;
BlockNumber blkno;
- PageOffset offset;
- OverflowPageAddress oaddr;
- SplitNumber splitnum;
+ uint32 splitnum;
uint32 *freep = NULL;
- uint32 max_free;
+ uint32 max_ovflpg;
uint32 bit;
uint32 first_page;
- uint32 free_bit;
- uint32 free_page;
- uint32 in_use_bits;
+ uint32 last_bit;
+ uint32 last_page;
uint32 i,
j;
- metap = (HashMetaPage) _hash_chgbufaccess(rel, metabufp, HASH_READ, HASH_WRITE);
-
+ _hash_chgbufaccess(rel, metabuf, HASH_READ, HASH_WRITE);
+ metap = (HashMetaPage) BufferGetPage(metabuf);
splitnum = metap->hashm_ovflpoint;
- max_free = metap->hashm_spares[splitnum];
- free_page = (max_free - 1) >> (metap->hashm_bshift + BYTE_TO_BIT);
- free_bit = (max_free - 1) & (BMPGSZ_BIT(metap) - 1);
+ /* end search with the last existing overflow page */
+ max_ovflpg = metap->hashm_spares[splitnum] - 1;
+ last_page = max_ovflpg >> BMPG_SHIFT(metap);
+ last_bit = max_ovflpg & BMPG_MASK(metap);
+
+ /* start search at hashm_firstfree */
+ first_page = metap->hashm_firstfree >> BMPG_SHIFT(metap);
+ bit = metap->hashm_firstfree & BMPG_MASK(metap);
+ j = bit / BITS_PER_MAP;
+ bit &= ~(BITS_PER_MAP - 1);
- /* Look through all the free maps to find the first free block */
- first_page = metap->hashm_lastfreed >> (metap->hashm_bshift + BYTE_TO_BIT);
- for (i = first_page; i <= free_page; i++)
+ for (i = first_page; i <= last_page; i++)
{
+ BlockNumber mapblkno;
Page mappage;
+ uint32 last_inpage;
- blkno = metap->hashm_mapp[i];
- mapbuf = _hash_getbuf(rel, blkno, HASH_WRITE);
+ mapblkno = metap->hashm_mapp[i];
+ mapbuf = _hash_getbuf(rel, mapblkno, HASH_WRITE);
mappage = BufferGetPage(mapbuf);
_hash_checkpage(mappage, LH_BITMAP_PAGE);
freep = HashPageGetBitmap(mappage);
- Assert(freep);
- if (i == free_page)
- in_use_bits = free_bit;
- else
- in_use_bits = BMPGSZ_BIT(metap) - 1;
-
- if (i == first_page)
- {
- bit = metap->hashm_lastfreed & (BMPGSZ_BIT(metap) - 1);
- j = bit / BITS_PER_MAP;
- bit = bit & ~(BITS_PER_MAP - 1);
- }
- else
+ if (i != first_page)
{
bit = 0;
j = 0;
}
- for (; bit <= in_use_bits; j++, bit += BITS_PER_MAP)
+
+ if (i == last_page)
+ last_inpage = last_bit;
+ else
+ last_inpage = BMPGSZ_BIT(metap) - 1;
+
+ for (; bit <= last_inpage; j++, bit += BITS_PER_MAP)
+ {
if (freep[j] != ALL_SET)
goto found;
+ }
+
+ _hash_relbuf(rel, mapbuf, HASH_WRITE);
}
/* No Free Page Found - have to allocate a new page */
- metap->hashm_lastfreed = metap->hashm_spares[splitnum];
+ bit = metap->hashm_spares[splitnum];
metap->hashm_spares[splitnum]++;
- offset = metap->hashm_spares[splitnum] -
- (splitnum ? metap->hashm_spares[splitnum - 1] : 0);
-
- if (offset > SPLITMASK)
- {
- if (++splitnum >= NCACHED)
- ereport(ERROR,
- (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
- errmsg("out of overflow pages in hash index \"%s\"",
- RelationGetRelationName(rel))));
- metap->hashm_ovflpoint = splitnum;
- metap->hashm_spares[splitnum] = metap->hashm_spares[splitnum - 1];
- metap->hashm_spares[splitnum - 1]--;
- offset = 0;
- }
/* Check if we need to allocate a new bitmap page */
- if (free_bit == (uint32) (BMPGSZ_BIT(metap) - 1))
+ if (last_bit == (uint32) (BMPGSZ_BIT(metap) - 1))
{
- /* won't be needing old map page */
-
- _hash_relbuf(rel, mapbuf, HASH_WRITE);
-
- free_page++;
- if (free_page >= NCACHED)
- ereport(ERROR,
- (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
- errmsg("out of overflow pages in hash index \"%s\"",
- RelationGetRelationName(rel))));
-
/*
- * This is tricky. The 1 indicates that you want the new page
- * allocated with 1 clear bit. Actually, you are going to
- * allocate 2 pages from this map. The first is going to be the
- * map page, the second is the overflow page we were looking for.
- * The init_bitmap routine automatically, sets the first bit of
- * itself to indicate that the bitmap itself is in use. We would
- * explicitly set the second bit, but don't have to if we tell
- * init_bitmap not to leave it clear in the first place.
+ * We create the new bitmap page with all pages marked "in use".
+ * Actually two pages in the new bitmap's range will exist
+ * immediately: the bitmap page itself, and the following page
+ * which is the one we return to the caller. Both of these are
+ * correctly marked "in use". Subsequent pages do not exist yet,
+ * but it is convenient to pre-mark them as "in use" too.
*/
- if (_hash_initbitmap(rel, metap, OADDR_OF(splitnum, offset),
- 1, free_page))
- elog(ERROR, "_hash_initbitmap failed");
+ _hash_initbitmap(rel, metap, bitno_to_blkno(metap, bit));
+
+ bit = metap->hashm_spares[splitnum];
metap->hashm_spares[splitnum]++;
- offset++;
- if (offset > SPLITMASK)
- {
- if (++splitnum >= NCACHED)
- ereport(ERROR,
- (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
- errmsg("out of overflow pages in hash index \"%s\"",
- RelationGetRelationName(rel))));
- metap->hashm_ovflpoint = splitnum;
- metap->hashm_spares[splitnum] = metap->hashm_spares[splitnum - 1];
- metap->hashm_spares[splitnum - 1]--;
- offset = 0;
- }
}
else
{
/*
- * Free_bit addresses the last used bit. Bump it to address the
- * first available bit.
+ * Nothing to do here; since the page was past the last used page,
+ * we know its bitmap bit was preinitialized to "in use".
*/
- free_bit++;
- SETBIT(freep, free_bit);
- _hash_wrtbuf(rel, mapbuf);
}
+ /* mark new page as first free so we don't search much next time */
+ metap->hashm_firstfree = bit;
+
/* Calculate address of the new overflow page */
- oaddr = OADDR_OF(splitnum, offset);
- _hash_chgbufaccess(rel, metabufp, HASH_WRITE, HASH_READ);
- return oaddr;
+ blkno = bitno_to_blkno(metap, bit);
+
+ _hash_chgbufaccess(rel, metabuf, HASH_WRITE, HASH_READ);
+
+ return blkno;
found:
- bit = bit + _hash_firstfreebit(freep[j]);
+ /* convert bit to bit number within page */
+ bit += _hash_firstfreebit(freep[j]);
+
+ /* mark page "in use" */
SETBIT(freep, bit);
_hash_wrtbuf(rel, mapbuf);
- /*
- * Bits are addressed starting with 0, but overflow pages are
- * addressed beginning at 1. Bit is a bit addressnumber, so we need to
- * increment it to convert it to a page number.
- */
+ /* convert bit to absolute bit number */
+ bit += (i << BMPG_SHIFT(metap));
- bit = 1 + bit + (i * BMPGSZ_BIT(metap));
- if (bit >= metap->hashm_lastfreed)
- metap->hashm_lastfreed = bit - 1;
+ /* adjust hashm_firstfree to avoid redundant searches */
+ if (bit > metap->hashm_firstfree)
+ metap->hashm_firstfree = bit;
- /* Calculate the split number for this page */
- for (i = 0; (i < splitnum) && (bit > metap->hashm_spares[i]); i++)
- ;
- offset = (i ? bit - metap->hashm_spares[i - 1] : bit);
- if (offset >= SPLITMASK)
- ereport(ERROR,
- (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
- errmsg("out of overflow pages in hash index \"%s\"",
- RelationGetRelationName(rel))));
+ blkno = bitno_to_blkno(metap, bit);
- /* initialize this page */
- oaddr = OADDR_OF(i, offset);
- _hash_chgbufaccess(rel, metabufp, HASH_WRITE, HASH_READ);
- return oaddr;
+ _hash_chgbufaccess(rel, metabuf, HASH_WRITE, HASH_READ);
+
+ return blkno;
}
/*
* _hash_firstfreebit()
*
- * Return the first bit that is not set in the argument 'map'. This
- * function is used to find an available overflow page within a
- * splitnumber.
- *
+ * Return the number of the first bit that is not set in the word 'map'.
*/
static uint32
_hash_firstfreebit(uint32 map)
@@ -279,7 +273,7 @@ _hash_firstfreebit(uint32 map)
{
if (!(mask & map))
return i;
- mask = mask << 1;
+ mask <<= 1;
}
return i;
}
@@ -287,27 +281,29 @@ _hash_firstfreebit(uint32 map)
/*
* _hash_freeovflpage() -
*
- * Mark this overflow page as free and return a buffer with
- * the page that follows it (which may be defined as
- * InvalidBuffer).
+ * Remove this overflow page from its bucket's chain, and mark the page as
+ * free. On entry, ovflbuf is write-locked; it is released before exiting.
+ *
+ * Returns the block number of the page that followed the given page
+ * in the bucket, or InvalidBlockNumber if no following page.
*
+ * NB: caller must not hold lock on metapage.
*/
-Buffer
+BlockNumber
_hash_freeovflpage(Relation rel, Buffer ovflbuf)
{
HashMetaPage metap;
Buffer metabuf;
Buffer mapbuf;
+ BlockNumber ovflblkno;
BlockNumber prevblkno;
BlockNumber blkno;
BlockNumber nextblkno;
HashPageOpaque ovflopaque;
Page ovflpage;
Page mappage;
- OverflowPageAddress addr;
- SplitNumber splitnum;
uint32 *freep;
- uint32 ovflpgno;
+ uint32 ovflbitno;
int32 bitmappage,
bitmapbit;
Bucket bucket;
@@ -316,10 +312,10 @@ _hash_freeovflpage(Relation rel, Buffer ovflbuf)
metap = (HashMetaPage) BufferGetPage(metabuf);
_hash_checkpage((Page) metap, LH_META_PAGE);
+ ovflblkno = BufferGetBlockNumber(ovflbuf);
ovflpage = BufferGetPage(ovflbuf);
_hash_checkpage(ovflpage, LH_OVERFLOW_PAGE);
ovflopaque = (HashPageOpaque) PageGetSpecialPointer(ovflpage);
- addr = ovflopaque->hasho_oaddr;
nextblkno = ovflopaque->hasho_nextblkno;
prevblkno = ovflopaque->hasho_prevblkno;
bucket = ovflopaque->hasho_bucket;
@@ -359,20 +355,17 @@ _hash_freeovflpage(Relation rel, Buffer ovflbuf)
}
/*
- * Fix up the overflow page bitmap that tracks this particular
- * overflow page. The bitmap can be found in the MetaPageData array
- * element hashm_mapp[bitmappage].
+ * Clear the bitmap bit to indicate that this overflow page is free.
*/
- splitnum = (addr >> SPLITSHIFT);
- ovflpgno = (splitnum ? metap->hashm_spares[splitnum - 1] : 0) + (addr & SPLITMASK) - 1;
+ ovflbitno = blkno_to_bitno(metap, ovflblkno);
- if (ovflpgno < metap->hashm_lastfreed)
- metap->hashm_lastfreed = ovflpgno;
-
- bitmappage = (ovflpgno >> (metap->hashm_bshift + BYTE_TO_BIT));
- bitmapbit = ovflpgno & (BMPGSZ_BIT(metap) - 1);
+ bitmappage = ovflbitno >> BMPG_SHIFT(metap);
+ bitmapbit = ovflbitno & BMPG_MASK(metap);
+ if (bitmappage >= metap->hashm_nmaps)
+ elog(ERROR, "invalid overflow bit number %u", ovflbitno);
blkno = metap->hashm_mapp[bitmappage];
+
mapbuf = _hash_getbuf(rel, blkno, HASH_WRITE);
mappage = BufferGetPage(mapbuf);
_hash_checkpage(mappage, LH_BITMAP_PAGE);
@@ -380,16 +373,13 @@ _hash_freeovflpage(Relation rel, Buffer ovflbuf)
CLRBIT(freep, bitmapbit);
_hash_wrtbuf(rel, mapbuf);
- _hash_relbuf(rel, metabuf, HASH_WRITE);
+ /* if this is now the first free page, update hashm_firstfree */
+ if (ovflbitno < metap->hashm_firstfree)
+ metap->hashm_firstfree = ovflbitno;
- /*
- * now instantiate the page that replaced this one, if it exists, and
- * return that buffer with a write lock.
- */
- if (BlockNumberIsValid(nextblkno))
- return _hash_getbuf(rel, nextblkno, HASH_WRITE);
- else
- return InvalidBuffer;
+ _hash_wrtbuf(rel, metabuf);
+
+ return nextblkno;
}
@@ -397,65 +387,49 @@ _hash_freeovflpage(Relation rel, Buffer ovflbuf)
* _hash_initbitmap()
*
* Initialize a new bitmap page. The metapage has a write-lock upon
- * entering the function.
+ * entering the function, and must be written by caller after return.
+ *
+ * 'blkno' is the block number of the new bitmap page.
*
- * 'pnum' is the OverflowPageAddress of the new bitmap page.
- * 'nbits' is how many bits to clear (i.e., make available) in the new
- * bitmap page. the remainder of the bits (as well as the first bit,
- * representing the bitmap page itself) will be set.
- * 'ndx' is the 0-based offset of the new bitmap page within the
- * metapage's array of bitmap page OverflowPageAddresses.
+ * All bits in the new bitmap page are set to "1", indicating "in use".
*/
-
-#define INT_MASK ((1 << INT_TO_BIT) -1)
-
-int32
-_hash_initbitmap(Relation rel,
- HashMetaPage metap,
- int32 pnum,
- int32 nbits,
- int32 ndx)
+void
+_hash_initbitmap(Relation rel, HashMetaPage metap, BlockNumber blkno)
{
Buffer buf;
- BlockNumber blkno;
Page pg;
HashPageOpaque op;
uint32 *freep;
- int clearbytes,
- clearints;
- blkno = OADDR_TO_BLKNO(pnum);
+ /* initialize the page */
buf = _hash_getbuf(rel, blkno, HASH_WRITE);
pg = BufferGetPage(buf);
_hash_pageinit(pg, BufferGetPageSize(buf));
op = (HashPageOpaque) PageGetSpecialPointer(pg);
- op->hasho_oaddr = InvalidOvflAddress;
+ op->hasho_oaddr = 0;
op->hasho_prevblkno = InvalidBlockNumber;
op->hasho_nextblkno = InvalidBlockNumber;
op->hasho_flag = LH_BITMAP_PAGE;
op->hasho_bucket = -1;
+ /* set all of the bits to 1 */
freep = HashPageGetBitmap(pg);
+ MemSet((char *) freep, 0xFF, BMPGSZ_BYTE(metap));
- /* set all of the bits above 'nbits' to 1 */
- clearints = ((nbits - 1) >> INT_TO_BIT) + 1;
- clearbytes = clearints << INT_TO_BYTE;
- MemSet((char *) freep, 0, clearbytes);
- MemSet(((char *) freep) + clearbytes, 0xFF,
- BMPGSZ_BYTE(metap) - clearbytes);
- freep[clearints - 1] = ALL_SET << (nbits & INT_MASK);
-
- /* bit 0 represents the new bitmap page */
- SETBIT(freep, 0);
+ /* write out the new bitmap page (releasing write lock) */
+ _hash_wrtbuf(rel, buf);
+ /* add the new bitmap page to the metapage's list of bitmaps */
/* metapage already has a write lock */
- metap->hashm_nmaps++;
- metap->hashm_mapp[ndx] = blkno;
+ if (metap->hashm_nmaps >= HASH_MAX_BITMAPS)
+ ereport(ERROR,
+ (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
+ errmsg("out of overflow pages in hash index \"%s\"",
+ RelationGetRelationName(rel))));
- /* write out the new bitmap page (releasing its locks) */
- _hash_wrtbuf(rel, buf);
+ metap->hashm_mapp[metap->hashm_nmaps] = blkno;
- return 0;
+ metap->hashm_nmaps++;
}
@@ -593,14 +567,8 @@ _hash_squeezebucket(Relation rel,
rblkno = ropaque->hasho_prevblkno;
Assert(BlockNumberIsValid(rblkno));
- /*
- * free this overflow page. the extra _hash_relbuf is because
- * _hash_freeovflpage gratuitously returns the next page (we
- * want the previous page and will get it ourselves later).
- */
- rbuf = _hash_freeovflpage(rel, rbuf);
- if (BufferIsValid(rbuf))
- _hash_relbuf(rel, rbuf, HASH_WRITE);
+ /* free this overflow page */
+ _hash_freeovflpage(rel, rbuf);
if (rblkno == wblkno)
{
diff --git a/src/backend/access/hash/hashpage.c b/src/backend/access/hash/hashpage.c
index b6ea8cf31a24ea4088edb6ffebe38f3b461f9c3a..e5e77c94b6be73257112b582846a89a1311a6926 100644
--- a/src/backend/access/hash/hashpage.c
+++ b/src/backend/access/hash/hashpage.c
@@ -8,19 +8,22 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/access/hash/hashpage.c,v 1.38 2003/08/04 02:39:57 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/access/hash/hashpage.c,v 1.39 2003/09/01 20:26:34 tgl Exp $
*
* NOTES
* Postgres hash pages look like ordinary relation pages. The opaque
* data at high addresses includes information about the page including
- * whether a page is an overflow page or a true bucket, the block
- * numbers of the preceding and following pages, and the overflow
- * address of the page if it is an overflow page.
+ * whether a page is an overflow page or a true bucket, the bucket
+ * number, and the block numbers of the preceding and following pages
+ * in the same bucket.
*
* The first page in a hash relation, page zero, is special -- it stores
* information describing the hash table; it is referred to as the
* "meta page." Pages one and higher store the actual data.
*
+ * There are also bitmap pages, which are not manipulated here;
+ * see hashovfl.c.
+ *
*-------------------------------------------------------------------------
*/
@@ -32,10 +35,6 @@
#include "storage/lmgr.h"
-static void _hash_setpagelock(Relation rel, BlockNumber blkno, int access);
-static void _hash_unsetpagelock(Relation rel, BlockNumber blkno, int access);
-static void _hash_splitpage(Relation rel, Buffer metabuf, Bucket obucket, Bucket nbucket);
-
/*
* We use high-concurrency locking on hash indices. There are two cases in
* which we don't do locking. One is when we're building the index.
@@ -62,9 +61,13 @@ static void _hash_splitpage(Relation rel, Buffer metabuf, Bucket obucket, Bucket
* the page being deleted, other than an indexscan of our own backend,
* which will be taken care of by _hash_adjscans.
*/
+#define USELOCKING (!BuildingHash && !IsInitProcessingMode())
-#define USELOCKING (!BuildingHash && !IsInitProcessingMode())
+static void _hash_setpagelock(Relation rel, BlockNumber blkno, int access);
+static void _hash_unsetpagelock(Relation rel, BlockNumber blkno, int access);
+static void _hash_splitbucket(Relation rel, Buffer metabuf,
+ Bucket obucket, Bucket nbucket);
/*
@@ -80,9 +83,6 @@ _hash_metapinit(Relation rel)
Buffer metabuf;
Buffer buf;
Page pg;
- int nbuckets;
- uint32 nelem; /* number elements */
- uint32 lg2nelem; /* _hash_log2(nelem) */
uint16 i;
/* can't be sharing this with anyone, now... */
@@ -95,63 +95,48 @@ _hash_metapinit(Relation rel)
metabuf = _hash_getbuf(rel, HASH_METAPAGE, HASH_WRITE);
pg = BufferGetPage(metabuf);
- metap = (HashMetaPage) pg;
_hash_pageinit(pg, BufferGetPageSize(metabuf));
+ pageopaque = (HashPageOpaque) PageGetSpecialPointer(pg);
+ pageopaque->hasho_oaddr = 0;
+ pageopaque->hasho_prevblkno = InvalidBlockNumber;
+ pageopaque->hasho_nextblkno = InvalidBlockNumber;
+ pageopaque->hasho_flag = LH_META_PAGE;
+ pageopaque->hasho_bucket = -1;
+
+ metap = (HashMetaPage) pg;
+
metap->hashm_magic = HASH_MAGIC;
metap->hashm_version = HASH_VERSION;
- metap->hashm_nkeys = 0;
+ metap->hashm_ntuples = 0;
metap->hashm_nmaps = 0;
metap->hashm_ffactor = DEFAULT_FFACTOR;
metap->hashm_bsize = BufferGetPageSize(metabuf);
metap->hashm_bshift = _hash_log2(metap->hashm_bsize);
- for (i = metap->hashm_bshift; i > 0; --i)
- {
- if ((1 << i) < (metap->hashm_bsize -
- (MAXALIGN(sizeof(PageHeaderData)) +
- MAXALIGN(sizeof(HashPageOpaqueData)))))
- break;
- }
- Assert(i);
- metap->hashm_bmsize = 1 << i;
+ /* page size must be power of 2 */
+ Assert(metap->hashm_bsize == (1 << metap->hashm_bshift));
+ /* bitmap size is half of page size, to keep it also power of 2 */
+ metap->hashm_bmsize = (metap->hashm_bsize >> 1);
+ Assert(metap->hashm_bsize >= metap->hashm_bmsize +
+ MAXALIGN(sizeof(PageHeaderData)) +
+ MAXALIGN(sizeof(HashPageOpaqueData)));
+ Assert((1 << BMPG_SHIFT(metap)) == (BMPG_MASK(metap) + 1));
+
metap->hashm_procid = index_getprocid(rel, 1, HASHPROC);
/*
- * Make nelem = 2 rather than 0 so that we end up allocating space for
- * the next greater power of two number of buckets.
+ * We initialize the index with two buckets, 0 and 1, occupying physical
+ * blocks 1 and 2. The first freespace bitmap page is in block 3.
*/
- nelem = 2;
- lg2nelem = 1; /* _hash_log2(MAX(nelem, 2)) */
- nbuckets = 2; /* 1 << lg2nelem */
-
- MemSet((char *) metap->hashm_spares, 0, sizeof(metap->hashm_spares));
- MemSet((char *) metap->hashm_mapp, 0, sizeof(metap->hashm_mapp));
-
- metap->hashm_spares[lg2nelem] = 2; /* lg2nelem + 1 */
- metap->hashm_spares[lg2nelem + 1] = 2; /* lg2nelem + 1 */
- metap->hashm_ovflpoint = 1; /* lg2nelem */
- metap->hashm_lastfreed = 2;
-
metap->hashm_maxbucket = metap->hashm_lowmask = 1; /* nbuckets - 1 */
metap->hashm_highmask = 3; /* (nbuckets << 1) - 1 */
- pageopaque = (HashPageOpaque) PageGetSpecialPointer(pg);
- pageopaque->hasho_oaddr = InvalidOvflAddress;
- pageopaque->hasho_prevblkno = InvalidBlockNumber;
- pageopaque->hasho_nextblkno = InvalidBlockNumber;
- pageopaque->hasho_flag = LH_META_PAGE;
- pageopaque->hasho_bucket = -1;
-
- /*
- * First bitmap page is at: splitpoint lg2nelem page offset 1 which
- * turns out to be page 3. Couldn't initialize page 3 until we
- * created the first two buckets above.
- */
- if (_hash_initbitmap(rel, metap, OADDR_OF(lg2nelem, 1), lg2nelem + 1, 0))
- elog(ERROR, "_hash_initbitmap failed");
+ MemSet((char *) metap->hashm_spares, 0, sizeof(metap->hashm_spares));
+ MemSet((char *) metap->hashm_mapp, 0, sizeof(metap->hashm_mapp));
- /* all done */
- _hash_wrtnorelbuf(metabuf);
+ metap->hashm_spares[1] = 1; /* the first bitmap page is only spare */
+ metap->hashm_ovflpoint = 1;
+ metap->hashm_firstfree = 0;
/*
* initialize the first two buckets
@@ -162,7 +147,7 @@ _hash_metapinit(Relation rel)
pg = BufferGetPage(buf);
_hash_pageinit(pg, BufferGetPageSize(buf));
pageopaque = (HashPageOpaque) PageGetSpecialPointer(pg);
- pageopaque->hasho_oaddr = InvalidOvflAddress;
+ pageopaque->hasho_oaddr = 0;
pageopaque->hasho_prevblkno = InvalidBlockNumber;
pageopaque->hasho_nextblkno = InvalidBlockNumber;
pageopaque->hasho_flag = LH_BUCKET_PAGE;
@@ -170,7 +155,14 @@ _hash_metapinit(Relation rel)
_hash_wrtbuf(rel, buf);
}
- _hash_relbuf(rel, metabuf, HASH_WRITE);
+ /*
+ * Initialize bitmap page. Can't do this until we
+ * create the first two buckets, else smgr will complain.
+ */
+ _hash_initbitmap(rel, metap, 3);
+
+ /* all done */
+ _hash_wrtbuf(rel, metabuf);
if (USELOCKING)
UnlockRelation(rel, AccessExclusiveLock);
@@ -267,30 +259,28 @@ _hash_wrtnorelbuf(Buffer buf)
WriteNoReleaseBuffer(buf);
}
-Page
+/*
+ * _hash_chgbufaccess() -- Change from read to write access or vice versa.
+ *
+ * When changing from write to read, we assume the buffer is dirty and tell
+ * bufmgr it must be written out.
+ */
+void
_hash_chgbufaccess(Relation rel,
- Buffer *bufp,
+ Buffer buf,
int from_access,
int to_access)
{
BlockNumber blkno;
- blkno = BufferGetBlockNumber(*bufp);
+ blkno = BufferGetBlockNumber(buf);
- switch (from_access)
- {
- case HASH_WRITE:
- _hash_wrtbuf(rel, *bufp);
- break;
- case HASH_READ:
- _hash_relbuf(rel, *bufp, from_access);
- break;
- default:
- elog(ERROR, "unrecognized hash access code: %d", from_access);
- break;
- }
- *bufp = _hash_getbuf(rel, blkno, to_access);
- return BufferGetPage(*bufp);
+ if (from_access == HASH_WRITE)
+ _hash_wrtnorelbuf(buf);
+
+ _hash_unsetpagelock(rel, blkno, from_access);
+
+ _hash_setpagelock(rel, blkno, to_access);
}
/*
@@ -303,12 +293,14 @@ _hash_pageinit(Page page, Size size)
PageInit(page, size, sizeof(HashPageOpaqueData));
}
+/*
+ * _hash_setpagelock() -- Acquire the requested type of lock on a page.
+ */
static void
_hash_setpagelock(Relation rel,
BlockNumber blkno,
int access)
{
-
if (USELOCKING)
{
switch (access)
@@ -326,12 +318,14 @@ _hash_setpagelock(Relation rel,
}
}
+/*
+ * _hash_unsetpagelock() -- Release the specified type of lock on a page.
+ */
static void
_hash_unsetpagelock(Relation rel,
BlockNumber blkno,
int access)
{
-
if (USELOCKING)
{
switch (access)
@@ -379,24 +373,22 @@ _hash_pagedel(Relation rel, ItemPointer tid)
opaque = (HashPageOpaque) PageGetSpecialPointer(page);
PageIndexTupleDelete(page, offno);
- _hash_wrtnorelbuf(buf);
if (PageIsEmpty(page) && (opaque->hasho_flag & LH_OVERFLOW_PAGE))
- {
- buf = _hash_freeovflpage(rel, buf);
- if (BufferIsValid(buf))
- _hash_relbuf(rel, buf, HASH_WRITE);
- }
+ _hash_freeovflpage(rel, buf);
else
- _hash_relbuf(rel, buf, HASH_WRITE);
+ _hash_wrtbuf(rel, buf);
metabuf = _hash_getbuf(rel, HASH_METAPAGE, HASH_WRITE);
metap = (HashMetaPage) BufferGetPage(metabuf);
_hash_checkpage((Page) metap, LH_META_PAGE);
- metap->hashm_nkeys--;
+ metap->hashm_ntuples--;
_hash_wrtbuf(rel, metabuf);
}
+/*
+ * Expand the hash table by creating one new bucket.
+ */
void
_hash_expandtable(Relation rel, Buffer metabuf)
{
@@ -408,53 +400,55 @@ _hash_expandtable(Relation rel, Buffer metabuf)
metap = (HashMetaPage) BufferGetPage(metabuf);
_hash_checkpage((Page) metap, LH_META_PAGE);
- metap = (HashMetaPage) _hash_chgbufaccess(rel, &metabuf, HASH_READ, HASH_WRITE);
+ _hash_chgbufaccess(rel, metabuf, HASH_READ, HASH_WRITE);
+
new_bucket = ++metap->hashm_maxbucket;
- metap = (HashMetaPage) _hash_chgbufaccess(rel, &metabuf, HASH_WRITE, HASH_READ);
- old_bucket = (metap->hashm_maxbucket & metap->hashm_lowmask);
+ old_bucket = (new_bucket & metap->hashm_lowmask);
+
+ if (new_bucket > metap->hashm_highmask)
+ {
+ /* Starting a new doubling */
+ metap->hashm_lowmask = metap->hashm_highmask;
+ metap->hashm_highmask = new_bucket | metap->hashm_lowmask;
+ }
/*
- * If the split point is increasing (hashm_maxbucket's log base 2 *
- * increases), we need to copy the current contents of the spare split
- * bucket to the next bucket.
+ * If the split point is increasing (hashm_maxbucket's log base 2
+ * increases), we need to adjust the hashm_spares[] array and
+ * hashm_ovflpoint so that future overflow pages will be created beyond
+ * this new batch of bucket pages.
+ *
+ * XXX should initialize new bucket pages to prevent out-of-order
+ * page creation.
*/
spare_ndx = _hash_log2(metap->hashm_maxbucket + 1);
if (spare_ndx > metap->hashm_ovflpoint)
{
-
- metap = (HashMetaPage) _hash_chgbufaccess(rel, &metabuf, HASH_READ, HASH_WRITE);
+ Assert(spare_ndx == metap->hashm_ovflpoint + 1);
metap->hashm_spares[spare_ndx] = metap->hashm_spares[metap->hashm_ovflpoint];
metap->hashm_ovflpoint = spare_ndx;
- metap = (HashMetaPage) _hash_chgbufaccess(rel, &metabuf, HASH_WRITE, HASH_READ);
}
- if (new_bucket > metap->hashm_highmask)
- {
-
- /* Starting a new doubling */
- metap = (HashMetaPage) _hash_chgbufaccess(rel, &metabuf, HASH_READ, HASH_WRITE);
- metap->hashm_lowmask = metap->hashm_highmask;
- metap->hashm_highmask = new_bucket | metap->hashm_lowmask;
- metap = (HashMetaPage) _hash_chgbufaccess(rel, &metabuf, HASH_WRITE, HASH_READ);
+ _hash_chgbufaccess(rel, metabuf, HASH_WRITE, HASH_READ);
- }
/* Relocate records to the new bucket */
- _hash_splitpage(rel, metabuf, old_bucket, new_bucket);
+ _hash_splitbucket(rel, metabuf, old_bucket, new_bucket);
}
/*
- * _hash_splitpage -- split 'obucket' into 'obucket' and 'nbucket'
+ * _hash_splitbucket -- split 'obucket' into 'obucket' and 'nbucket'
*
- * this routine is actually misnamed -- we are splitting a bucket that
- * consists of a base bucket page and zero or more overflow (bucket
- * chain) pages.
+ * We are splitting a bucket that consists of a base bucket page and zero
+ * or more overflow (bucket chain) pages. We must relocate tuples that
+ * belong in the new bucket, and compress out any free space in the old
+ * bucket.
*/
static void
-_hash_splitpage(Relation rel,
- Buffer metabuf,
- Bucket obucket,
- Bucket nbucket)
+_hash_splitbucket(Relation rel,
+ Buffer metabuf,
+ Bucket obucket,
+ Bucket nbucket)
{
Bucket bucket;
Buffer obuf;
@@ -475,7 +469,7 @@ _hash_splitpage(Relation rel,
OffsetNumber omaxoffnum;
Page opage;
Page npage;
- TupleDesc itupdesc;
+ TupleDesc itupdesc = RelationGetDescr(rel);
metap = (HashMetaPage) BufferGetPage(metabuf);
_hash_checkpage((Page) metap, LH_META_PAGE);
@@ -488,13 +482,13 @@ _hash_splitpage(Relation rel,
opage = BufferGetPage(obuf);
npage = BufferGetPage(nbuf);
- /* initialize the new bucket */
+ /* initialize the new bucket page */
_hash_pageinit(npage, BufferGetPageSize(nbuf));
nopaque = (HashPageOpaque) PageGetSpecialPointer(npage);
nopaque->hasho_prevblkno = InvalidBlockNumber;
nopaque->hasho_nextblkno = InvalidBlockNumber;
nopaque->hasho_flag = LH_BUCKET_PAGE;
- nopaque->hasho_oaddr = InvalidOvflAddress;
+ nopaque->hasho_oaddr = 0;
nopaque->hasho_bucket = nbucket;
_hash_wrtnorelbuf(nbuf);
@@ -569,11 +563,11 @@ _hash_splitpage(Relation rel,
else
{
/*
- * we're at the end of the bucket chain, so now we're
- * really done with everything. before quitting, call
- * _hash_squeezebucket to ensure the tuples in the bucket
- * (including the overflow pages) are packed as tightly as
- * possible.
+ * We're at the end of the bucket chain, so now we're
+ * really done with everything. Before quitting, call
+ * _hash_squeezebucket to ensure the tuples remaining in the
+ * old bucket (including the overflow pages) are packed as
+ * tightly as possible. The new bucket is already tight.
*/
_hash_wrtbuf(rel, obuf);
_hash_wrtbuf(rel, nbuf);
@@ -585,8 +579,9 @@ _hash_splitpage(Relation rel,
/* hash on the tuple */
hitem = (HashItem) PageGetItem(opage, PageGetItemId(opage, ooffnum));
itup = &(hitem->hash_itup);
- itupdesc = RelationGetDescr(rel);
datum = index_getattr(itup, 1, itupdesc, &null);
+ Assert(!null);
+
bucket = _hash_call(rel, metap, datum);
if (bucket == nbucket)
@@ -603,7 +598,7 @@ _hash_splitpage(Relation rel,
if (PageGetFreeSpace(npage) < itemsz)
{
- ovflbuf = _hash_addovflpage(rel, &metabuf, nbuf);
+ ovflbuf = _hash_addovflpage(rel, metabuf, nbuf);
_hash_wrtbuf(rel, nbuf);
nbuf = ovflbuf;
npage = BufferGetPage(nbuf);
@@ -638,10 +633,10 @@ _hash_splitpage(Relation rel,
if (PageIsEmpty(opage) &&
(oopaque->hasho_flag & LH_OVERFLOW_PAGE))
{
- obuf = _hash_freeovflpage(rel, obuf);
+ oblkno = _hash_freeovflpage(rel, obuf);
/* check that we're not through the bucket chain */
- if (BufferIsInvalid(obuf))
+ if (!BlockNumberIsValid(oblkno))
{
_hash_wrtbuf(rel, nbuf);
_hash_squeezebucket(rel, metap, obucket);
@@ -652,9 +647,9 @@ _hash_splitpage(Relation rel,
* re-init. again, we're guaranteed that an ovfl page has
* at least one tuple.
*/
+ obuf = _hash_getbuf(rel, oblkno, HASH_WRITE);
opage = BufferGetPage(obuf);
_hash_checkpage(opage, LH_OVERFLOW_PAGE);
- oblkno = BufferGetBlockNumber(obuf);
oopaque = (HashPageOpaque) PageGetSpecialPointer(opage);
if (PageIsEmpty(opage))
elog(ERROR, "empty hash overflow page %u", oblkno);
@@ -668,10 +663,8 @@ _hash_splitpage(Relation rel,
* the tuple stays on this page. we didn't move anything, so
* we didn't delete anything and therefore we don't have to
* change 'omaxoffnum'.
- *
- * XXX any hash value from [0, nbucket-1] will map to this
- * bucket, which doesn't make sense to me.
*/
+ Assert(bucket == obucket);
ooffnum = OffsetNumberNext(ooffnum);
}
}
diff --git a/src/include/access/hash.h b/src/include/access/hash.h
index 821f8348e8e7ca0fc828c59e6d1fe0fa39d71506..83aae20c1cae384e58a5a5459fd1a79f33828031 100644
--- a/src/include/access/hash.h
+++ b/src/include/access/hash.h
@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $Id: hash.h,v 1.49 2003/08/04 02:40:10 momjian Exp $
+ * $Id: hash.h,v 1.50 2003/09/01 20:26:34 tgl Exp $
*
* NOTES
* modeled after Margo Seltzer's hash implementation for unix.
@@ -24,43 +24,18 @@
#include "fmgr.h"
/*
- * An overflow page is a spare page allocated for storing data whose
- * bucket doesn't have room to store it. We use overflow pages rather
- * than just splitting the bucket because there is a linear order in
- * the way we split buckets. In other words, if there isn't enough space
- * in the bucket itself, put it in an overflow page.
- *
- * Overflow page addresses are stored in form: (Splitnumber, Page offset).
- *
- * A splitnumber is the number of the generation where the table doubles
- * in size. The ovflpage's offset within the splitnumber; offsets start
- * at 1.
- *
- * We convert the stored bitmap address into a page address with the
- * macro OADDR_OF(S, O) where S is the splitnumber and O is the page
- * offset.
+ * Mapping from hash bucket number to physical block number of bucket's
+ * starting page. Beware of multiple evaluations of argument! Also notice
+ * macro's implicit dependency on "metap".
*/
typedef uint32 Bucket;
-typedef bits16 OverflowPageAddress;
-typedef uint32 SplitNumber;
-typedef uint32 PageOffset;
-
-/* A valid overflow address will always have a page offset >= 1 */
-#define InvalidOvflAddress 0
-
-#define SPLITSHIFT 11
-#define SPLITMASK 0x7FF
-#define SPLITNUM(N) ((SplitNumber)(((uint32)(N)) >> SPLITSHIFT))
-#define OPAGENUM(N) ((PageOffset)((N) & SPLITMASK))
-#define OADDR_OF(S,O) ((OverflowPageAddress)((uint32)((uint32)(S) << SPLITSHIFT) + (O)))
#define BUCKET_TO_BLKNO(B) \
- ((Bucket) ((B) + ((B) ? metap->hashm_spares[_hash_log2((B)+1)-1] : 0)) + 1)
-#define OADDR_TO_BLKNO(B) \
- ((BlockNumber) \
- (BUCKET_TO_BLKNO ( (1 << SPLITNUM((B))) -1 ) + OPAGENUM((B))));
+ ((BlockNumber) ((B) + ((B) ? metap->hashm_spares[_hash_log2((B)+1)-1] : 0)) + 1)
/*
+ * Special space for hash index pages.
+ *
* hasho_flag tells us which type of page we're looking at. For
* example, knowing overflow pages from bucket pages is necessary
* information when you're deleting tuples from a page. If all the
@@ -69,7 +44,6 @@ typedef uint32 PageOffset;
* the tuples are deleted from a bucket page, no additional action is
* necessary.
*/
-
#define LH_UNUSED_PAGE (0)
#define LH_OVERFLOW_PAGE (1 << 0)
#define LH_BUCKET_PAGE (1 << 1)
@@ -78,9 +52,9 @@ typedef uint32 PageOffset;
typedef struct HashPageOpaqueData
{
- bits16 hasho_flag; /* is this page a bucket or ovfl */
+ bits16 hasho_flag; /* page type code, see above */
Bucket hasho_bucket; /* bucket number this pg belongs to */
- OverflowPageAddress hasho_oaddr; /* ovfl address of this ovfl pg */
+ bits16 hasho_oaddr; /* no longer used; delete someday */
BlockNumber hasho_nextblkno; /* next ovfl blkno */
BlockNumber hasho_prevblkno; /* previous ovfl (or bucket) blkno */
} HashPageOpaqueData;
@@ -91,10 +65,8 @@ typedef HashPageOpaqueData *HashPageOpaque;
* ScanOpaqueData is used to remember which buffers we're currently
* examining in the scan. We keep these buffers locked and pinned and
* recorded in the opaque entry of the scan in order to avoid doing a
- * ReadBuffer() for every tuple in the index. This avoids semop() calls,
- * which are expensive.
+ * ReadBuffer() for every tuple in the index.
*/
-
typedef struct HashScanOpaqueData
{
Buffer hashso_curbuf;
@@ -113,60 +85,55 @@ typedef HashScanOpaqueData *HashScanOpaque;
#define HASH_VERSION 0
/*
- * NCACHED is used to set the array sizeof spares[] & bitmaps[].
+ * Spares[] holds the number of overflow pages currently allocated at or
+ * before a certain splitpoint. For example, if spares[3] = 7 then there are
+ * 7 ovflpages before splitpoint 3 (compare BUCKET_TO_BLKNO macro). The
+ * value in spares[ovflpoint] increases as overflow pages are added at the
+ * end of the index. Once ovflpoint increases (ie, we have actually allocated
+ * the bucket pages belonging to that splitpoint) the number of spares at the
+ * prior splitpoint cannot change anymore.
*
- * Spares[] is used to hold the number overflow pages currently
- * allocated at a certain splitpoint. For example, if spares[3] = 7
- * then there are a maximum of 7 ovflpages available at splitpoint 3.
- * The value in spares[] will change as ovflpages are added within
- * a splitpoint.
+ * ovflpages that have been recycled for reuse can be found by looking at
+ * bitmaps that are stored within ovflpages dedicated for the purpose.
+ * The blknos of these bitmap pages are kept in bitmaps[]; nmaps is the
+ * number of currently existing bitmaps.
*
- * Within a splitpoint, one can find which ovflpages are available and
- * which are used by looking at a bitmaps that are stored on the ovfl
- * pages themselves. There is at least one bitmap for every splitpoint's
- * ovflpages. Bitmaps[] contains the ovflpage addresses of the ovflpages
- * that hold the ovflpage bitmaps.
- *
- * The reason that the size is restricted to NCACHED (32) is because
- * the bitmaps are 16 bits: upper 5 represent the splitpoint, lower 11
- * indicate the page number within the splitpoint. Since there are
- * only 5 bits to store the splitpoint, there can only be 32 splitpoints.
- * Both spares[] and bitmaps[] use splitpoints as there indices, so there
- * can only be 32 of them.
+ * The limitation on the size of spares[] comes from the fact that there's
+ * no point in having more than 2^32 buckets with only uint32 hashcodes.
+ * There is no particularly good reason for bitmaps[] to be the same size,
+ * but we're stuck with that until we want to force an initdb. (With 8K
+ * block size, 32 bitmaps limit us to 8 Gb of overflow space...)
*/
-
-#define NCACHED 32
-
+#define HASH_MAX_SPLITPOINTS 32
+#define HASH_MAX_BITMAPS 32
typedef struct HashMetaPageData
{
PageHeaderData hashm_phdr; /* pad for page header (do not use) */
uint32 hashm_magic; /* magic no. for hash tables */
uint32 hashm_version; /* version ID */
- uint32 hashm_nkeys; /* number of keys stored in the table */
- uint16 hashm_ffactor; /* fill factor */
- uint16 hashm_bsize; /* bucket size (bytes) - must be a power
+ uint32 hashm_ntuples; /* number of tuples stored in the table */
+ uint16 hashm_ffactor; /* target fill factor (tuples/bucket) */
+ uint16 hashm_bsize; /* index page size (bytes) - must be a power
* of 2 */
- uint16 hashm_bshift; /* bucket shift */
- uint16 hashm_bmsize; /* bitmap array size (bytes) - must be a
- * power of 2 */
+ uint16 hashm_bshift; /* log2(bsize) */
+ uint16 hashm_bmsize; /* bitmap array size (bytes) - must be
+ * exactly half of hashm_bsize */
uint32 hashm_maxbucket; /* ID of maximum bucket in use */
uint32 hashm_highmask; /* mask to modulo into entire table */
uint32 hashm_lowmask; /* mask to modulo into lower half of table */
- uint32 hashm_ovflpoint;/* pageno. from which ovflpgs being
+ uint32 hashm_ovflpoint;/* splitpoint from which ovflpgs being
* allocated */
- uint32 hashm_lastfreed; /* last ovflpage freed */
- uint32 hashm_nmaps; /* Initial number of bitmaps */
- uint32 hashm_spares[NCACHED]; /* spare pages available at
- * splitpoints */
- BlockNumber hashm_mapp[NCACHED]; /* blknumbers of ovfl page maps */
+ uint32 hashm_firstfree; /* lowest-number free ovflpage (bit#) */
+ uint32 hashm_nmaps; /* number of bitmap pages */
+ uint32 hashm_spares[HASH_MAX_SPLITPOINTS]; /* spare pages before
+ * each splitpoint */
+ BlockNumber hashm_mapp[HASH_MAX_BITMAPS]; /* blknos of ovfl bitmaps */
RegProcedure hashm_procid; /* hash procedure id from pg_proc */
} HashMetaPageData;
typedef HashMetaPageData *HashMetaPage;
-extern bool BuildingHash;
-
typedef struct HashItemData
{
IndexTupleData hash_itup;
@@ -178,31 +145,33 @@ typedef HashItemData *HashItem;
* Constants
*/
#define DEFAULT_FFACTOR 300
-#define SPLITMAX 8
#define BYTE_TO_BIT 3 /* 2^3 bits/byte */
-#define INT_TO_BYTE 2 /* 2^2 bytes/int */
-#define INT_TO_BIT 5 /* 2^5 bits/int */
#define ALL_SET ((uint32) ~0)
/*
- * bitmap pages do not contain tuples. they do contain the standard
+ * Bitmap pages do not contain tuples. They do contain the standard
* page headers and trailers; however, everything in between is a
- * giant bit array. the number of bits that fit on a page obviously
- * depends on the page size and the header/trailer overhead.
+ * giant bit array. The number of bits that fit on a page obviously
+ * depends on the page size and the header/trailer overhead. In the
+ * present implementation, we use exactly half of a page for bitmap,
+ * so that we have a power-of-2 bits per page.
+ *
+ * The fact that the metapage has separate bsize and bmsize fields,
+ * but only one bshift field, is a design error that ought to be fixed.
*/
#define BMPGSZ_BYTE(metap) ((metap)->hashm_bmsize)
#define BMPGSZ_BIT(metap) ((metap)->hashm_bmsize << BYTE_TO_BIT)
+#define BMPG_SHIFT(metap) ((metap)->hashm_bshift - 1 + BYTE_TO_BIT)
+#define BMPG_MASK(metap) (BMPGSZ_BIT(metap) - 1)
#define HashPageGetBitmap(pg) \
((uint32 *) (((char *) (pg)) + MAXALIGN(sizeof(PageHeaderData))))
/*
- * The number of bits in an ovflpage bitmap which
- * tells which ovflpages are empty versus in use (NOT the number of
- * bits in an overflow page *address* bitmap).
+ * The number of bits in an ovflpage bitmap word.
*/
-#define BITS_PER_MAP 32 /* Number of bits in ovflpage bitmap */
+#define BITS_PER_MAP 32 /* Number of bits in uint32 */
-/* Given the address of the beginning of a big map, clear/set the nth bit */
+/* Given the address of the beginning of a bit map, clear/set the nth bit */
#define CLRBIT(A, N) ((A)[(N)/BITS_PER_MAP] &= ~(1<<((N)%BITS_PER_MAP)))
#define SETBIT(A, N) ((A)[(N)/BITS_PER_MAP] |= (1<<((N)%BITS_PER_MAP)))
#define ISSET(A, N) ((A)[(N)/BITS_PER_MAP] & (1<<((N)%BITS_PER_MAP)))
@@ -213,18 +182,9 @@ typedef HashItemData *HashItem;
#define HASH_READ 0
#define HASH_WRITE 1
-/*
- * In general, the hash code tries to localize its knowledge about page
- * layout to a couple of routines. However, we need a special value to
- * indicate "no page number" in those places where we expect page numbers.
- */
-
-#define P_NONE 0
-
/*
* Strategy number. There's only one valid strategy for hashing: equality.
*/
-
#define HTEqualStrategyNumber 1
#define HTMaxStrategyNumber 1
@@ -233,9 +193,11 @@ typedef HashItemData *HashItem;
* us with an amproc procudure for hashing a key of the new type.
* Since we only have one such proc in amproc, it's number 1.
*/
-
#define HASHPROC 1
+
+extern bool BuildingHash;
+
/* public routines */
extern Datum hashbuild(PG_FUNCTION_ARGS);
@@ -276,36 +238,32 @@ extern Datum hash_any(register const unsigned char *k, register int keylen);
/* hashinsert.c */
extern InsertIndexResult _hash_doinsert(Relation rel, HashItem hitem);
-
/* hashovfl.c */
-extern Buffer _hash_addovflpage(Relation rel, Buffer *metabufp, Buffer buf);
-extern Buffer _hash_freeovflpage(Relation rel, Buffer ovflbuf);
-extern int32 _hash_initbitmap(Relation rel, HashMetaPage metap, int32 pnum,
- int32 nbits, int32 ndx);
+extern Buffer _hash_addovflpage(Relation rel, Buffer metabuf, Buffer buf);
+extern BlockNumber _hash_freeovflpage(Relation rel, Buffer ovflbuf);
+extern void _hash_initbitmap(Relation rel, HashMetaPage metap,
+ BlockNumber blkno);
extern void _hash_squeezebucket(Relation rel, HashMetaPage metap,
Bucket bucket);
-
/* hashpage.c */
extern void _hash_metapinit(Relation rel);
extern Buffer _hash_getbuf(Relation rel, BlockNumber blkno, int access);
extern void _hash_relbuf(Relation rel, Buffer buf, int access);
extern void _hash_wrtbuf(Relation rel, Buffer buf);
extern void _hash_wrtnorelbuf(Buffer buf);
-extern Page _hash_chgbufaccess(Relation rel, Buffer *bufp, int from_access,
+extern void _hash_chgbufaccess(Relation rel, Buffer buf, int from_access,
int to_access);
extern void _hash_pageinit(Page page, Size size);
extern void _hash_pagedel(Relation rel, ItemPointer tid);
extern void _hash_expandtable(Relation rel, Buffer metabuf);
-
/* hashscan.c */
extern void _hash_regscan(IndexScanDesc scan);
extern void _hash_dropscan(IndexScanDesc scan);
extern void _hash_adjscans(Relation rel, ItemPointer tid);
extern void AtEOXact_hash(void);
-
/* hashsearch.c */
extern void _hash_search(Relation rel, int keysz, ScanKey scankey,
Buffer *bufP, HashMetaPage metap);
@@ -314,7 +272,6 @@ extern bool _hash_first(IndexScanDesc scan, ScanDirection dir);
extern bool _hash_step(IndexScanDesc scan, Buffer *bufP, ScanDirection dir,
Buffer metabuf);
-
/* hashutil.c */
extern ScanKey _hash_mkscankey(Relation rel, IndexTuple itup);
extern void _hash_freeskey(ScanKey skey);
@@ -324,7 +281,6 @@ extern Bucket _hash_call(Relation rel, HashMetaPage metap, Datum key);
extern uint32 _hash_log2(uint32 num);
extern void _hash_checkpage(Page page, int flags);
-
/* hash.c */
extern void hash_redo(XLogRecPtr lsn, XLogRecord *record);
extern void hash_undo(XLogRecPtr lsn, XLogRecord *record);