#include "utils/rel.h"
-static Buffer _hash_getovflpage(Relation rel, Buffer metabuf);
static uint32 _hash_firstfreebit(uint32 map);
Page ovflpage;
HashPageOpaque pageopaque;
HashPageOpaque ovflopaque;
-
- /* allocate and lock an empty overflow page */
- ovflbuf = _hash_getovflpage(rel, metabuf);
+ HashMetaPage metap;
+ Buffer mapbuf = InvalidBuffer;
+ Buffer newmapbuf = InvalidBuffer;
+ BlockNumber blkno;
+ uint32 orig_firstfree;
+ uint32 splitnum;
+ uint32 *freep = NULL;
+ uint32 max_ovflpg;
+ uint32 bit;
+ uint32 bitmap_page_bit;
+ uint32 first_page;
+ uint32 last_bit;
+ uint32 last_page;
+ uint32 i,
+ j;
+ bool page_found = false;
/*
- * Write-lock the tail page. It is okay to hold two buffer locks here
- * since there cannot be anyone else contending for access to ovflbuf.
+ * Write-lock the tail page. Here, we need to maintain locking order such
+ * that, first acquire the lock on tail page of bucket, then on meta page
+ * to find and lock the bitmap page and if it is found, then lock on meta
+ * page is released, then finally acquire the lock on new overflow buffer.
+ * We need this locking order to avoid deadlock with backends that are
+ * doing inserts.
*/
LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE);
buf = _hash_getbuf(rel, nextblkno, HASH_WRITE, LH_OVERFLOW_PAGE);
}
- /* now that we have correct backlink, initialize new overflow page */
- ovflpage = BufferGetPage(ovflbuf);
- ovflopaque = (HashPageOpaque) PageGetSpecialPointer(ovflpage);
- ovflopaque->hasho_prevblkno = BufferGetBlockNumber(buf);
- ovflopaque->hasho_nextblkno = InvalidBlockNumber;
- ovflopaque->hasho_bucket = pageopaque->hasho_bucket;
- ovflopaque->hasho_flag = LH_OVERFLOW_PAGE;
- ovflopaque->hasho_page_id = HASHO_PAGE_ID;
-
- MarkBufferDirty(ovflbuf);
-
- /* logically chain overflow page to previous page */
- pageopaque->hasho_nextblkno = BufferGetBlockNumber(ovflbuf);
- MarkBufferDirty(buf);
- if (retain_pin)
- {
- /* pin will be retained only for the primary bucket page */
- Assert(pageopaque->hasho_flag & LH_BUCKET_PAGE);
- LockBuffer(buf, BUFFER_LOCK_UNLOCK);
- }
- else
- _hash_relbuf(rel, buf);
-
- return ovflbuf;
-}
-
-/*
- * _hash_getovflpage()
- *
- * Find an available overflow page and return it. The returned buffer
- * is pinned and write-locked, and has had _hash_pageinit() applied,
- * but it is caller's responsibility to fill the special space.
- *
- * The caller must hold a pin, but no lock, on the metapage buffer.
- * That buffer is left in the same state at exit.
- */
-static Buffer
-_hash_getovflpage(Relation rel, Buffer metabuf)
-{
- HashMetaPage metap;
- Buffer mapbuf = 0;
- Buffer newbuf;
- BlockNumber blkno;
- uint32 orig_firstfree;
- uint32 splitnum;
- uint32 *freep = NULL;
- uint32 max_ovflpg;
- uint32 bit;
- uint32 first_page;
- uint32 last_bit;
- uint32 last_page;
- uint32 i,
- j;
-
/* Get exclusive lock on the meta page */
LockBuffer(metabuf, BUFFER_LOCK_EXCLUSIVE);
for (; bit <= last_inpage; j++, bit += BITS_PER_MAP)
{
if (freep[j] != ALL_SET)
+ {
+ page_found = true;
+
+ /* Reacquire exclusive lock on the meta page */
+ LockBuffer(metabuf, BUFFER_LOCK_EXCLUSIVE);
+
+ /* convert bit to bit number within page */
+ bit += _hash_firstfreebit(freep[j]);
+ bitmap_page_bit = bit;
+
+ /* convert bit to absolute bit number */
+ bit += (i << BMPG_SHIFT(metap));
+ /* Calculate address of the recycled overflow page */
+ blkno = bitno_to_blkno(metap, bit);
+
+ /* Fetch and init the recycled page */
+ ovflbuf = _hash_getinitbuf(rel, blkno);
+
goto found;
+ }
}
/* No free space here, try to advance to next map page */
_hash_relbuf(rel, mapbuf);
+ mapbuf = InvalidBuffer;
i++;
j = 0; /* scan from start of next map page */
bit = 0;
* convenient to pre-mark them as "in use" too.
*/
bit = metap->hashm_spares[splitnum];
- _hash_initbitmap(rel, metap, bitno_to_blkno(metap, bit), MAIN_FORKNUM);
- metap->hashm_spares[splitnum]++;
+
+ /* metapage already has a write lock */
+ 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))));
+
+ newmapbuf = _hash_getnewbuf(rel, bitno_to_blkno(metap, bit), MAIN_FORKNUM);
}
else
{
}
/* Calculate address of the new overflow page */
- bit = metap->hashm_spares[splitnum];
+ bit = BufferIsValid(newmapbuf) ?
+ metap->hashm_spares[splitnum] + 1 : metap->hashm_spares[splitnum];
blkno = bitno_to_blkno(metap, bit);
/*
* relation length stays in sync with ours. XXX It's annoying to do this
* with metapage write lock held; would be better to use a lock that
* doesn't block incoming searches.
+ *
+ * It is okay to hold two buffer locks here (one on tail page of bucket
+ * and other on new overflow page) since there cannot be anyone else
+ * contending for access to ovflbuf.
*/
- newbuf = _hash_getnewbuf(rel, blkno, MAIN_FORKNUM);
+ ovflbuf = _hash_getnewbuf(rel, blkno, MAIN_FORKNUM);
- metap->hashm_spares[splitnum]++;
+found:
/*
- * Adjust hashm_firstfree to avoid redundant searches. But don't risk
- * changing it if someone moved it while we were searching bitmap pages.
+ * Do the update.
*/
- if (metap->hashm_firstfree == orig_firstfree)
- metap->hashm_firstfree = bit + 1;
-
- /* Write updated metapage and release lock, but not pin */
- MarkBufferDirty(metabuf);
- LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
-
- return newbuf;
-
-found:
- /* convert bit to bit number within page */
- bit += _hash_firstfreebit(freep[j]);
-
- /* mark page "in use" in the bitmap */
- SETBIT(freep, bit);
- MarkBufferDirty(mapbuf);
- _hash_relbuf(rel, mapbuf);
+ if (page_found)
+ {
+ Assert(BufferIsValid(mapbuf));
- /* Reacquire exclusive lock on the meta page */
- LockBuffer(metabuf, BUFFER_LOCK_EXCLUSIVE);
+ /* mark page "in use" in the bitmap */
+ SETBIT(freep, bitmap_page_bit);
+ MarkBufferDirty(mapbuf);
+ }
+ else
+ {
+ /* update the count to indicate new overflow page is added */
+ metap->hashm_spares[splitnum]++;
- /* convert bit to absolute bit number */
- bit += (i << BMPG_SHIFT(metap));
+ if (BufferIsValid(newmapbuf))
+ {
+ _hash_initbitmapbuffer(newmapbuf, metap->hashm_bmsize, false);
+ MarkBufferDirty(newmapbuf);
+
+ /* add the new bitmap page to the metapage's list of bitmaps */
+ metap->hashm_mapp[metap->hashm_nmaps] = BufferGetBlockNumber(newmapbuf);
+ metap->hashm_nmaps++;
+ metap->hashm_spares[splitnum]++;
+ MarkBufferDirty(metabuf);
+ }
- /* Calculate address of the recycled overflow page */
- blkno = bitno_to_blkno(metap, bit);
+ /*
+ * for new overflow page, we don't need to explicitly set the bit in
+ * bitmap page, as by default that will be set to "in use".
+ */
+ }
/*
* Adjust hashm_firstfree to avoid redundant searches. But don't risk
if (metap->hashm_firstfree == orig_firstfree)
{
metap->hashm_firstfree = bit + 1;
-
- /* Write updated metapage and release lock, but not pin */
MarkBufferDirty(metabuf);
- LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
}
+
+ /* initialize new overflow page */
+ ovflpage = BufferGetPage(ovflbuf);
+ ovflopaque = (HashPageOpaque) PageGetSpecialPointer(ovflpage);
+ ovflopaque->hasho_prevblkno = BufferGetBlockNumber(buf);
+ ovflopaque->hasho_nextblkno = InvalidBlockNumber;
+ ovflopaque->hasho_bucket = pageopaque->hasho_bucket;
+ ovflopaque->hasho_flag = LH_OVERFLOW_PAGE;
+ ovflopaque->hasho_page_id = HASHO_PAGE_ID;
+
+ MarkBufferDirty(ovflbuf);
+
+ /* logically chain overflow page to previous page */
+ pageopaque->hasho_nextblkno = BufferGetBlockNumber(ovflbuf);
+
+ MarkBufferDirty(buf);
+
+ if (retain_pin)
+ LockBuffer(buf, BUFFER_LOCK_UNLOCK);
else
- {
- /* We didn't change the metapage, so no need to write */
- LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
- }
+ _hash_relbuf(rel, buf);
+
+ if (BufferIsValid(mapbuf))
+ _hash_relbuf(rel, mapbuf);
+
+ LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
+
+ if (BufferIsValid(newmapbuf))
+ _hash_relbuf(rel, newmapbuf);
- /* Fetch, init, and return the recycled page */
- return _hash_getinitbuf(rel, blkno);
+ return ovflbuf;
}
/*
}
+/*
+ * _hash_initbitmapbuffer()
+ *
+ * Initialize a new bitmap page. All bits in the new bitmap page are set to
+ * "1", indicating "in use".
+ */
+void
+_hash_initbitmapbuffer(Buffer buf, uint16 bmsize, bool initpage)
+{
+ Page pg;
+ HashPageOpaque op;
+ uint32 *freep;
+
+ pg = BufferGetPage(buf);
+
+ /* initialize the page */
+ if (initpage)
+ _hash_pageinit(pg, BufferGetPageSize(buf));
+
+ /* initialize the page's special space */
+ op = (HashPageOpaque) PageGetSpecialPointer(pg);
+ op->hasho_prevblkno = InvalidBlockNumber;
+ op->hasho_nextblkno = InvalidBlockNumber;
+ op->hasho_bucket = -1;
+ op->hasho_flag = LH_BITMAP_PAGE;
+ op->hasho_page_id = HASHO_PAGE_ID;
+
+ /* set all of the bits to 1 */
+ freep = HashPageGetBitmap(pg);
+ MemSet(freep, 0xFF, bmsize);
+
+ /* Set pd_lower just past the end of the bitmap page data. */
+ ((PageHeader) pg)->pd_lower = ((char *) freep + bmsize) - (char *) pg;
+}
+
+
/*
* _hash_squeezebucket(rel, bucket)
*
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