hashpage.c File Reference

#include "postgres.h"
#include "access/hash.h"
#include "access/hash_xlog.h"
#include "access/xloginsert.h"
#include "miscadmin.h"
#include "port/pg_bitutils.h"
#include "storage/predicate.h"
#include "storage/smgr.h"
#include "utils/rel.h"

Include dependency graph for hashpage.c:

Go to the source code of this file.

Functions
static bool	_hash_alloc_buckets (Relation rel, BlockNumber firstblock, uint32 nblocks)
static void	_hash_splitbucket (Relation rel, Buffer metabuf, Bucket obucket, Bucket nbucket, Buffer obuf, Buffer nbuf, HTAB *htab, uint32 maxbucket, uint32 highmask, uint32 lowmask)
static void	log_split_page (Relation rel, Buffer buf)
Buffer	_hash_getbuf (Relation rel, BlockNumber blkno, int access, int flags)
Buffer	_hash_getbuf_with_condlock_cleanup (Relation rel, BlockNumber blkno, int flags)
Buffer	_hash_getinitbuf (Relation rel, BlockNumber blkno)
void	_hash_initbuf (Buffer buf, uint32 max_bucket, uint32 num_bucket, uint32 flag, bool initpage)
Buffer	_hash_getnewbuf (Relation rel, BlockNumber blkno, ForkNumber forkNum)
Buffer	_hash_getbuf_with_strategy (Relation rel, BlockNumber blkno, int access, int flags, BufferAccessStrategy bstrategy)
void	_hash_relbuf (Relation rel, Buffer buf)
void	_hash_dropbuf (Relation rel, Buffer buf)
void	_hash_dropscanbuf (Relation rel, HashScanOpaque so)
uint32	_hash_init (Relation rel, double num_tuples, ForkNumber forkNum)
void	_hash_init_metabuffer (Buffer buf, double num_tuples, RegProcedure procid, uint16 ffactor, bool initpage)
void	_hash_pageinit (Page page, Size size)
void	_hash_expandtable (Relation rel, Buffer metabuf)
void	_hash_finish_split (Relation rel, Buffer metabuf, Buffer obuf, Bucket obucket, uint32 maxbucket, uint32 highmask, uint32 lowmask)
HashMetaPage	_hash_getcachedmetap (Relation rel, Buffer *metabuf, bool force_refresh)
Buffer	_hash_getbucketbuf_from_hashkey (Relation rel, uint32 hashkey, int access, HashMetaPage *cachedmetap)

Function Documentation

_hash_alloc_buckets()

static bool _hash_alloc_buckets ( Relation  rel, BlockNumber  firstblock, uint32  nblocks  )

static

Definition at line 994 of file hashpage.c.

{
    BlockNumber lastblock;
    PGIOAlignedBlock zerobuf;
    Page        page;
    HashPageOpaque ovflopaque;
 
    lastblock = firstblock + nblocks - 1;
 
    /*
     * Check for overflow in block number calculation; if so, we cannot extend
     * the index anymore.
     */
    if (lastblock < firstblock || lastblock == InvalidBlockNumber)
        return false;
 
    page = (Page) zerobuf.data;
 
    /*
     * Initialize the page.  Just zeroing the page won't work; see
     * _hash_freeovflpage for similar usage.  We take care to make the special
     * space valid for the benefit of tools such as pageinspect.
     */
    _hash_pageinit(page, BLCKSZ);
 
    ovflopaque = HashPageGetOpaque(page);
 
    ovflopaque->hasho_prevblkno = InvalidBlockNumber;
    ovflopaque->hasho_nextblkno = InvalidBlockNumber;
    ovflopaque->hasho_bucket = InvalidBucket;
    ovflopaque->hasho_flag = LH_UNUSED_PAGE;
    ovflopaque->hasho_page_id = HASHO_PAGE_ID;
 
    if (RelationNeedsWAL(rel))
        log_newpage(&rel->rd_locator,
                    MAIN_FORKNUM,
                    lastblock,
                    zerobuf.data,
                    true);
 
    PageSetChecksum(page, lastblock);
    smgrextend(RelationGetSmgr(rel), MAIN_FORKNUM, lastblock, zerobuf.data,
               false);
 
    return true;
}

References _hash_pageinit(), fb(), HASHO_PAGE_ID, HashPageGetOpaque, InvalidBlockNumber, InvalidBucket, LH_UNUSED_PAGE, log_newpage(), MAIN_FORKNUM, PageSetChecksum(), RelationData::rd_locator, RelationGetSmgr(), RelationNeedsWAL, and smgrextend().

Referenced by _hash_expandtable().

_hash_dropbuf()

void _hash_dropbuf	(	Relation	rel,
		Buffer	buf
	)

Definition at line 277 of file hashpage.c.

{
    ReleaseBuffer(buf);
}

References buf, and ReleaseBuffer().

Referenced by _hash_doinsert(), _hash_dropscanbuf(), _hash_expandtable(), _hash_finish_split(), _hash_first(), _hash_getbucketbuf_from_hashkey(), _hash_next(), _hash_readprev(), and hashbulkdelete().

_hash_dropscanbuf()

void _hash_dropscanbuf	(	Relation	rel,
		HashScanOpaque	so
	)

Definition at line 289 of file hashpage.c.

{
    /* release pin we hold on primary bucket page */
    if (BufferIsValid(so->hashso_bucket_buf) &&
        so->hashso_bucket_buf != so->currPos.buf)
        _hash_dropbuf(rel, so->hashso_bucket_buf);
    so->hashso_bucket_buf = InvalidBuffer;
 
    /* release pin we hold on primary bucket page  of bucket being split */
    if (BufferIsValid(so->hashso_split_bucket_buf) &&
        so->hashso_split_bucket_buf != so->currPos.buf)
        _hash_dropbuf(rel, so->hashso_split_bucket_buf);
    so->hashso_split_bucket_buf = InvalidBuffer;
 
    /* release any pin we still hold */
    if (BufferIsValid(so->currPos.buf))
        _hash_dropbuf(rel, so->currPos.buf);
    so->currPos.buf = InvalidBuffer;
 
    /* reset split scan */
    so->hashso_buc_populated = false;
    so->hashso_buc_split = false;
}

References _hash_dropbuf(), BufferIsValid(), fb(), and InvalidBuffer.

Referenced by _hash_next(), hashendscan(), and hashrescan().

_hash_expandtable()

void _hash_expandtable	(	Relation	rel,
		Buffer	metabuf
	)

Definition at line 614 of file hashpage.c.

{
    HashMetaPage metap;
    Bucket      old_bucket;
    Bucket      new_bucket;
    uint32      spare_ndx;
    BlockNumber start_oblkno;
    BlockNumber start_nblkno;
    Buffer      buf_nblkno;
    Buffer      buf_oblkno;
    Page        opage;
    Page        npage;
    HashPageOpaque oopaque;
    HashPageOpaque nopaque;
    uint32      maxbucket;
    uint32      highmask;
    uint32      lowmask;
    bool        metap_update_masks = false;
    bool        metap_update_splitpoint = false;
    XLogRecPtr  recptr;
 
restart_expand:
 
    /*
     * Write-lock the meta page.  It used to be necessary to acquire a
     * heavyweight lock to begin a split, but that is no longer required.
     */
    LockBuffer(metabuf, BUFFER_LOCK_EXCLUSIVE);
 
    _hash_checkpage(rel, metabuf, LH_META_PAGE);
    metap = HashPageGetMeta(BufferGetPage(metabuf));
 
    /*
     * Check to see if split is still needed; someone else might have already
     * done one while we waited for the lock.
     *
     * Make sure this stays in sync with _hash_doinsert()
     */
    if (metap->hashm_ntuples <=
        (double) metap->hashm_ffactor * (metap->hashm_maxbucket + 1))
        goto fail;
 
    /*
     * Can't split anymore if maxbucket has reached its maximum possible
     * value.
     *
     * Ideally we'd allow bucket numbers up to UINT_MAX-1 (no higher because
     * the calculation maxbucket+1 mustn't overflow).  Currently we restrict
     * to half that to prevent failure of pg_ceil_log2_32() and insufficient
     * space in hashm_spares[].  It's moot anyway because an index with 2^32
     * buckets would certainly overflow BlockNumber and hence
     * _hash_alloc_buckets() would fail, but if we supported buckets smaller
     * than a disk block then this would be an independent constraint.
     *
     * If you change this, see also the maximum initial number of buckets in
     * _hash_init().
     */
    if (metap->hashm_maxbucket >= (uint32) 0x7FFFFFFE)
        goto fail;
 
    /*
     * Determine which bucket is to be split, and attempt to take cleanup lock
     * on the old bucket.  If we can't get the lock, give up.
     *
     * The cleanup lock protects us not only against other backends, but
     * against our own backend as well.
     *
     * The cleanup lock is mainly to protect the split from concurrent
     * inserts. See src/backend/access/hash/README, Lock Definitions for
     * further details.  Due to this locking restriction, if there is any
     * pending scan, the split will give up which is not good, but harmless.
     */
    new_bucket = metap->hashm_maxbucket + 1;
 
    old_bucket = (new_bucket & metap->hashm_lowmask);
 
    start_oblkno = BUCKET_TO_BLKNO(metap, old_bucket);
 
    buf_oblkno = _hash_getbuf_with_condlock_cleanup(rel, start_oblkno, LH_BUCKET_PAGE);
    if (!buf_oblkno)
        goto fail;
 
    opage = BufferGetPage(buf_oblkno);
    oopaque = HashPageGetOpaque(opage);
 
    /*
     * We want to finish the split from a bucket as there is no apparent
     * benefit by not doing so and it will make the code complicated to finish
     * the split that involves multiple buckets considering the case where new
     * split also fails.  We don't need to consider the new bucket for
     * completing the split here as it is not possible that a re-split of new
     * bucket starts when there is still a pending split from old bucket.
     */
    if (H_BUCKET_BEING_SPLIT(oopaque))
    {
        /*
         * Copy bucket mapping info now; refer the comment in code below where
         * we copy this information before calling _hash_splitbucket to see
         * why this is okay.
         */
        maxbucket = metap->hashm_maxbucket;
        highmask = metap->hashm_highmask;
        lowmask = metap->hashm_lowmask;
 
        /*
         * Release the lock on metapage and old_bucket, before completing the
         * split.
         */
        LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
        LockBuffer(buf_oblkno, BUFFER_LOCK_UNLOCK);
 
        _hash_finish_split(rel, metabuf, buf_oblkno, old_bucket, maxbucket,
                           highmask, lowmask);
 
        /* release the pin on old buffer and retry for expand. */
        _hash_dropbuf(rel, buf_oblkno);
 
        goto restart_expand;
    }
 
    /*
     * Clean the tuples remained from the previous split.  This operation
     * requires cleanup lock and we already have one on the old bucket, so
     * let's do it. We also don't want to allow further splits from the bucket
     * till the garbage of previous split is cleaned.  This has two
     * advantages; first, it helps in avoiding the bloat due to garbage and
     * second is, during cleanup of bucket, we are always sure that the
     * garbage tuples belong to most recently split bucket.  On the contrary,
     * if we allow cleanup of bucket after meta page is updated to indicate
     * the new split and before the actual split, the cleanup operation won't
     * be able to decide whether the tuple has been moved to the newly created
     * bucket and ended up deleting such tuples.
     */
    if (H_NEEDS_SPLIT_CLEANUP(oopaque))
    {
        /*
         * Copy bucket mapping info now; refer to the comment in code below
         * where we copy this information before calling _hash_splitbucket to
         * see why this is okay.
         */
        maxbucket = metap->hashm_maxbucket;
        highmask = metap->hashm_highmask;
        lowmask = metap->hashm_lowmask;
 
        /* Release the metapage lock. */
        LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
 
        hashbucketcleanup(rel, old_bucket, buf_oblkno, start_oblkno, NULL,
                          maxbucket, highmask, lowmask, NULL, NULL, true,
                          NULL, NULL);
 
        _hash_dropbuf(rel, buf_oblkno);
 
        goto restart_expand;
    }
 
    /*
     * There shouldn't be any active scan on new bucket.
     *
     * Note: it is safe to compute the new bucket's blkno here, even though we
     * may still need to update the BUCKET_TO_BLKNO mapping.  This is because
     * the current value of hashm_spares[hashm_ovflpoint] correctly shows
     * where we are going to put a new splitpoint's worth of buckets.
     */
    start_nblkno = BUCKET_TO_BLKNO(metap, new_bucket);
 
    /*
     * If the split point is increasing we need to allocate a new batch of
     * bucket pages.
     */
    spare_ndx = _hash_spareindex(new_bucket + 1);
    if (spare_ndx > metap->hashm_ovflpoint)
    {
        uint32      buckets_to_add;
 
        Assert(spare_ndx == metap->hashm_ovflpoint + 1);
 
        /*
         * We treat allocation of buckets as a separate WAL-logged action.
         * Even if we fail after this operation, won't leak bucket pages;
         * rather, the next split will consume this space. In any case, even
         * without failure we don't use all the space in one split operation.
         */
        buckets_to_add = _hash_get_totalbuckets(spare_ndx) - new_bucket;
        if (!_hash_alloc_buckets(rel, start_nblkno, buckets_to_add))
        {
            /* can't split due to BlockNumber overflow */
            _hash_relbuf(rel, buf_oblkno);
            goto fail;
        }
    }
 
    /*
     * Physically allocate the new bucket's primary page.  We want to do this
     * before changing the metapage's mapping info, in case we can't get the
     * disk space.
     *
     * XXX It doesn't make sense to call _hash_getnewbuf first, zeroing the
     * buffer, and then only afterwards check whether we have a cleanup lock.
     * However, since no scan can be accessing the buffer yet, any concurrent
     * accesses will just be from processes like the bgwriter or checkpointer
     * which don't care about its contents, so it doesn't really matter.
     */
    buf_nblkno = _hash_getnewbuf(rel, start_nblkno, MAIN_FORKNUM);
    if (!IsBufferCleanupOK(buf_nblkno))
    {
        _hash_relbuf(rel, buf_oblkno);
        _hash_relbuf(rel, buf_nblkno);
        goto fail;
    }
 
    /*
     * Since we are scribbling on the pages in the shared buffers, establish a
     * critical section.  Any failure in this next code leaves us with a big
     * problem: the metapage is effectively corrupt but could get written back
     * to disk.
     */
    START_CRIT_SECTION();
 
    /*
     * Okay to proceed with split.  Update the metapage bucket mapping info.
     */
    metap->hashm_maxbucket = new_bucket;
 
    if (new_bucket > metap->hashm_highmask)
    {
        /* Starting a new doubling */
        metap->hashm_lowmask = metap->hashm_highmask;
        metap->hashm_highmask = new_bucket | metap->hashm_lowmask;
        metap_update_masks = true;
    }
 
    /*
     * If the split point is increasing 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.
     */
    if (spare_ndx > metap->hashm_ovflpoint)
    {
        metap->hashm_spares[spare_ndx] = metap->hashm_spares[metap->hashm_ovflpoint];
        metap->hashm_ovflpoint = spare_ndx;
        metap_update_splitpoint = true;
    }
 
    MarkBufferDirty(metabuf);
 
    /*
     * Copy bucket mapping info now; this saves re-accessing the meta page
     * inside _hash_splitbucket's inner loop.  Note that once we drop the
     * split lock, other splits could begin, so these values might be out of
     * date before _hash_splitbucket finishes.  That's okay, since all it
     * needs is to tell which of these two buckets to map hashkeys into.
     */
    maxbucket = metap->hashm_maxbucket;
    highmask = metap->hashm_highmask;
    lowmask = metap->hashm_lowmask;
 
    opage = BufferGetPage(buf_oblkno);
    oopaque = HashPageGetOpaque(opage);
 
    /*
     * Mark the old bucket to indicate that split is in progress.  (At
     * operation end, we will clear the split-in-progress flag.)  Also, for a
     * primary bucket page, hasho_prevblkno stores the number of buckets that
     * existed as of the last split, so we must update that value here.
     */
    oopaque->hasho_flag |= LH_BUCKET_BEING_SPLIT;
    oopaque->hasho_prevblkno = maxbucket;
 
    MarkBufferDirty(buf_oblkno);
 
    npage = BufferGetPage(buf_nblkno);
 
    /*
     * initialize the new bucket's primary page and mark it to indicate that
     * split is in progress.
     */
    nopaque = HashPageGetOpaque(npage);
    nopaque->hasho_prevblkno = maxbucket;
    nopaque->hasho_nextblkno = InvalidBlockNumber;
    nopaque->hasho_bucket = new_bucket;
    nopaque->hasho_flag = LH_BUCKET_PAGE | LH_BUCKET_BEING_POPULATED;
    nopaque->hasho_page_id = HASHO_PAGE_ID;
 
    MarkBufferDirty(buf_nblkno);
 
    /* XLOG stuff */
    if (RelationNeedsWAL(rel))
    {
        xl_hash_split_allocate_page xlrec;
 
        xlrec.new_bucket = maxbucket;
        xlrec.old_bucket_flag = oopaque->hasho_flag;
        xlrec.new_bucket_flag = nopaque->hasho_flag;
        xlrec.flags = 0;
 
        XLogBeginInsert();
 
        XLogRegisterBuffer(0, buf_oblkno, REGBUF_STANDARD);
        XLogRegisterBuffer(1, buf_nblkno, REGBUF_WILL_INIT);
        XLogRegisterBuffer(2, metabuf, REGBUF_STANDARD);
 
        if (metap_update_masks)
        {
            xlrec.flags |= XLH_SPLIT_META_UPDATE_MASKS;
            XLogRegisterBufData(2, &metap->hashm_lowmask, sizeof(uint32));
            XLogRegisterBufData(2, &metap->hashm_highmask, sizeof(uint32));
        }
 
        if (metap_update_splitpoint)
        {
            xlrec.flags |= XLH_SPLIT_META_UPDATE_SPLITPOINT;
            XLogRegisterBufData(2, &metap->hashm_ovflpoint,
                                sizeof(uint32));
            XLogRegisterBufData(2,
                                &metap->hashm_spares[metap->hashm_ovflpoint],
                                sizeof(uint32));
        }
 
        XLogRegisterData(&xlrec, SizeOfHashSplitAllocPage);
 
        recptr = XLogInsert(RM_HASH_ID, XLOG_HASH_SPLIT_ALLOCATE_PAGE);
    }
    else
        recptr = XLogGetFakeLSN(rel);
 
    PageSetLSN(BufferGetPage(buf_oblkno), recptr);
    PageSetLSN(BufferGetPage(buf_nblkno), recptr);
    PageSetLSN(BufferGetPage(metabuf), recptr);
 
    END_CRIT_SECTION();
 
    /* drop lock, but keep pin */
    LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
 
    /* Relocate records to the new bucket */
    _hash_splitbucket(rel, metabuf,
                      old_bucket, new_bucket,
                      buf_oblkno, buf_nblkno, NULL,
                      maxbucket, highmask, lowmask);
 
    /* all done, now release the pins on primary buckets. */
    _hash_dropbuf(rel, buf_oblkno);
    _hash_dropbuf(rel, buf_nblkno);
 
    return;
 
    /* Here if decide not to split or fail to acquire old bucket lock */
fail:
 
    /* We didn't write the metapage, so just drop lock */
    LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
}

References _hash_alloc_buckets(), _hash_checkpage(), _hash_dropbuf(), _hash_finish_split(), _hash_get_totalbuckets(), _hash_getbuf_with_condlock_cleanup(), _hash_getnewbuf(), _hash_relbuf(), _hash_spareindex(), _hash_splitbucket(), Assert, BUCKET_TO_BLKNO, BUFFER_LOCK_EXCLUSIVE, BUFFER_LOCK_UNLOCK, BufferGetPage(), END_CRIT_SECTION, fb(), H_BUCKET_BEING_SPLIT, H_NEEDS_SPLIT_CLEANUP, hashbucketcleanup(), HashMetaPageData::hashm_ffactor, HashMetaPageData::hashm_highmask, HashMetaPageData::hashm_lowmask, HashMetaPageData::hashm_maxbucket, HashMetaPageData::hashm_ntuples, HashMetaPageData::hashm_ovflpoint, HashMetaPageData::hashm_spares, HASHO_PAGE_ID, HashPageGetMeta, HashPageGetOpaque, InvalidBlockNumber, IsBufferCleanupOK(), LH_BUCKET_BEING_POPULATED, LH_BUCKET_BEING_SPLIT, LH_BUCKET_PAGE, LH_META_PAGE, LockBuffer(), MAIN_FORKNUM, MarkBufferDirty(), xl_hash_split_allocate_page::new_bucket, PageSetLSN(), REGBUF_STANDARD, REGBUF_WILL_INIT, RelationNeedsWAL, SizeOfHashSplitAllocPage, START_CRIT_SECTION, XLH_SPLIT_META_UPDATE_MASKS, XLH_SPLIT_META_UPDATE_SPLITPOINT, XLOG_HASH_SPLIT_ALLOCATE_PAGE, XLogBeginInsert(), XLogGetFakeLSN(), XLogInsert(), XLogRegisterBufData(), XLogRegisterBuffer(), and XLogRegisterData().

Referenced by _hash_doinsert().

_hash_finish_split()

void _hash_finish_split	(	Relation	rel,
		Buffer	metabuf,
		Buffer	obuf,
		Bucket	obucket,
		uint32	maxbucket,
		uint32	highmask,
		uint32	lowmask
	)

Definition at line 1360 of file hashpage.c.

{
    HASHCTL     hash_ctl;
    HTAB       *tidhtab;
    Buffer      bucket_nbuf = InvalidBuffer;
    Buffer      nbuf;
    Page        npage;
    BlockNumber nblkno;
    BlockNumber bucket_nblkno;
    HashPageOpaque npageopaque;
    Bucket      nbucket;
    bool        found;
 
    /* Initialize hash tables used to track TIDs */
    hash_ctl.keysize = sizeof(ItemPointerData);
    hash_ctl.entrysize = sizeof(ItemPointerData);
    hash_ctl.hcxt = CurrentMemoryContext;
 
    tidhtab =
        hash_create("bucket ctids",
                    256,        /* arbitrary initial size */
                    &hash_ctl,
                    HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
 
    bucket_nblkno = nblkno = _hash_get_newblock_from_oldbucket(rel, obucket);
 
    /*
     * Scan the new bucket and build hash table of TIDs
     */
    for (;;)
    {
        OffsetNumber noffnum;
        OffsetNumber nmaxoffnum;
 
        nbuf = _hash_getbuf(rel, nblkno, HASH_READ,
                            LH_BUCKET_PAGE | LH_OVERFLOW_PAGE);
 
        /* remember the primary bucket buffer to acquire cleanup lock on it. */
        if (nblkno == bucket_nblkno)
            bucket_nbuf = nbuf;
 
        npage = BufferGetPage(nbuf);
        npageopaque = HashPageGetOpaque(npage);
 
        /* Scan each tuple in new page */
        nmaxoffnum = PageGetMaxOffsetNumber(npage);
        for (noffnum = FirstOffsetNumber;
             noffnum <= nmaxoffnum;
             noffnum = OffsetNumberNext(noffnum))
        {
            IndexTuple  itup;
 
            /* Fetch the item's TID and insert it in hash table. */
            itup = (IndexTuple) PageGetItem(npage,
                                            PageGetItemId(npage, noffnum));
 
            (void) hash_search(tidhtab, &itup->t_tid, HASH_ENTER, &found);
 
            Assert(!found);
        }
 
        nblkno = npageopaque->hasho_nextblkno;
 
        /*
         * release our write lock without modifying buffer and ensure to
         * retain the pin on primary bucket.
         */
        if (nbuf == bucket_nbuf)
            LockBuffer(nbuf, BUFFER_LOCK_UNLOCK);
        else
            _hash_relbuf(rel, nbuf);
 
        /* Exit loop if no more overflow pages in new bucket */
        if (!BlockNumberIsValid(nblkno))
            break;
    }
 
    /*
     * Conditionally get the cleanup lock on old and new buckets to perform
     * the split operation.  If we don't get the cleanup locks, silently give
     * up and next insertion on old bucket will try again to complete the
     * split.
     */
    if (!ConditionalLockBufferForCleanup(obuf))
    {
        hash_destroy(tidhtab);
        return;
    }
    if (!ConditionalLockBufferForCleanup(bucket_nbuf))
    {
        LockBuffer(obuf, BUFFER_LOCK_UNLOCK);
        hash_destroy(tidhtab);
        return;
    }
 
    npage = BufferGetPage(bucket_nbuf);
    npageopaque = HashPageGetOpaque(npage);
    nbucket = npageopaque->hasho_bucket;
 
    _hash_splitbucket(rel, metabuf, obucket,
                      nbucket, obuf, bucket_nbuf, tidhtab,
                      maxbucket, highmask, lowmask);
 
    _hash_dropbuf(rel, bucket_nbuf);
    hash_destroy(tidhtab);
}

References _hash_dropbuf(), _hash_get_newblock_from_oldbucket(), _hash_getbuf(), _hash_relbuf(), _hash_splitbucket(), Assert, BlockNumberIsValid(), BUFFER_LOCK_UNLOCK, BufferGetPage(), ConditionalLockBufferForCleanup(), CurrentMemoryContext, fb(), FirstOffsetNumber, HASH_BLOBS, HASH_CONTEXT, hash_create(), hash_destroy(), HASH_ELEM, HASH_ENTER, HASH_READ, hash_search(), HashPageGetOpaque, InvalidBuffer, LH_BUCKET_PAGE, LH_OVERFLOW_PAGE, LockBuffer(), OffsetNumberNext, PageGetItem(), PageGetItemId(), PageGetMaxOffsetNumber(), and IndexTupleData::t_tid.

Referenced by _hash_doinsert(), and _hash_expandtable().

_hash_getbucketbuf_from_hashkey()

Buffer _hash_getbucketbuf_from_hashkey	(	Relation	rel,
		uint32	hashkey,
		int	access,
		HashMetaPage *	cachedmetap
	)

Definition at line 1563 of file hashpage.c.

{
    HashMetaPage metap;
    Buffer      buf;
    Buffer      metabuf = InvalidBuffer;
    Page        page;
    Bucket      bucket;
    BlockNumber blkno;
    HashPageOpaque opaque;
 
    /* We read from target bucket buffer, hence locking is must. */
    Assert(access == HASH_READ || access == HASH_WRITE);
 
    metap = _hash_getcachedmetap(rel, &metabuf, false);
    Assert(metap != NULL);
 
    /*
     * Loop until we get a lock on the correct target bucket.
     */
    for (;;)
    {
        /*
         * Compute the target bucket number, and convert to block number.
         */
        bucket = _hash_hashkey2bucket(hashkey,
                                      metap->hashm_maxbucket,
                                      metap->hashm_highmask,
                                      metap->hashm_lowmask);
 
        blkno = BUCKET_TO_BLKNO(metap, bucket);
 
        /* Fetch the primary bucket page for the bucket */
        buf = _hash_getbuf(rel, blkno, access, LH_BUCKET_PAGE);
        page = BufferGetPage(buf);
        opaque = HashPageGetOpaque(page);
        Assert(opaque->hasho_bucket == bucket);
        Assert(opaque->hasho_prevblkno != InvalidBlockNumber);
 
        /*
         * If this bucket hasn't been split, we're done.
         */
        if (opaque->hasho_prevblkno <= metap->hashm_maxbucket)
            break;
 
        /* Drop lock on this buffer, update cached metapage, and retry. */
        _hash_relbuf(rel, buf);
        metap = _hash_getcachedmetap(rel, &metabuf, true);
        Assert(metap != NULL);
    }
 
    if (BufferIsValid(metabuf))
        _hash_dropbuf(rel, metabuf);
 
    if (cachedmetap)
        *cachedmetap = metap;
 
    return buf;
}

References _hash_dropbuf(), _hash_getbuf(), _hash_getcachedmetap(), _hash_hashkey2bucket(), _hash_relbuf(), Assert, BUCKET_TO_BLKNO, buf, BufferGetPage(), BufferIsValid(), fb(), HASH_READ, HASH_WRITE, HashMetaPageData::hashm_highmask, HashMetaPageData::hashm_lowmask, HashMetaPageData::hashm_maxbucket, HashPageOpaqueData::hasho_bucket, HashPageOpaqueData::hasho_prevblkno, HashPageGetOpaque, InvalidBlockNumber, InvalidBuffer, and LH_BUCKET_PAGE.

Referenced by _hash_doinsert(), and _hash_first().

_hash_getbuf()

Buffer _hash_getbuf	(	Relation	rel,
		BlockNumber	blkno,
		int	access,
		int	flags
	)

Definition at line 70 of file hashpage.c.

{
    Buffer      buf;
 
    if (blkno == P_NEW)
        elog(ERROR, "hash AM does not use P_NEW");
 
    buf = ReadBuffer(rel, blkno);
 
    if (access != HASH_NOLOCK)
        LockBuffer(buf, access);
 
    /* ref count and lock type are correct */
 
    _hash_checkpage(rel, buf, flags);
 
    return buf;
}

References _hash_checkpage(), buf, elog, ERROR, HASH_NOLOCK, LockBuffer(), P_NEW, and ReadBuffer().

Referenced by _hash_addovflpage(), _hash_doinsert(), _hash_finish_split(), _hash_first(), _hash_freeovflpage(), _hash_get_newblock_from_oldbucket(), _hash_get_oldblock_from_newbucket(), _hash_getbucketbuf_from_hashkey(), _hash_getcachedmetap(), _hash_kill_items(), _hash_next(), _hash_readnext(), _hash_readprev(), _hash_splitbucket(), hash_bitmap_info(), hashbulkdelete(), and pgstathashindex().

_hash_getbuf_with_condlock_cleanup()

Buffer _hash_getbuf_with_condlock_cleanup	(	Relation	rel,
		BlockNumber	blkno,
		int	flags
	)

Definition at line 96 of file hashpage.c.

{
    Buffer      buf;
 
    if (blkno == P_NEW)
        elog(ERROR, "hash AM does not use P_NEW");
 
    buf = ReadBuffer(rel, blkno);
 
    if (!ConditionalLockBufferForCleanup(buf))
    {
        ReleaseBuffer(buf);
        return InvalidBuffer;
    }
 
    /* ref count and lock type are correct */
 
    _hash_checkpage(rel, buf, flags);
 
    return buf;
}

References _hash_checkpage(), buf, ConditionalLockBufferForCleanup(), elog, ERROR, InvalidBuffer, P_NEW, ReadBuffer(), and ReleaseBuffer().

Referenced by _hash_expandtable().

_hash_getbuf_with_strategy()

Buffer _hash_getbuf_with_strategy	(	Relation	rel,
		BlockNumber	blkno,
		int	access,
		int	flags,
		BufferAccessStrategy	bstrategy
	)

Definition at line 239 of file hashpage.c.

{
    Buffer      buf;
 
    if (blkno == P_NEW)
        elog(ERROR, "hash AM does not use P_NEW");
 
    buf = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_NORMAL, bstrategy);
 
    if (access != HASH_NOLOCK)
        LockBuffer(buf, access);
 
    /* ref count and lock type are correct */
 
    _hash_checkpage(rel, buf, flags);
 
    return buf;
}

References _hash_checkpage(), buf, elog, ERROR, HASH_NOLOCK, LockBuffer(), MAIN_FORKNUM, P_NEW, RBM_NORMAL, and ReadBufferExtended().

Referenced by _hash_freeovflpage(), _hash_squeezebucket(), and hashbucketcleanup().

_hash_getcachedmetap()

HashMetaPage _hash_getcachedmetap	(	Relation	rel,
		Buffer *	metabuf,
		bool	force_refresh
	)

Definition at line 1505 of file hashpage.c.

{
    Page        page;
 
    Assert(metabuf);
    if (force_refresh || rel->rd_amcache == NULL)
    {
        char       *cache = NULL;
 
        /*
         * It's important that we don't set rd_amcache to an invalid value.
         * Either MemoryContextAlloc or _hash_getbuf could fail, so don't
         * install a pointer to the newly-allocated storage in the actual
         * relcache entry until both have succeeded.
         */
        if (rel->rd_amcache == NULL)
            cache = MemoryContextAlloc(rel->rd_indexcxt,
                                       sizeof(HashMetaPageData));
 
        /* Read the metapage. */
        if (BufferIsValid(*metabuf))
            LockBuffer(*metabuf, BUFFER_LOCK_SHARE);
        else
            *metabuf = _hash_getbuf(rel, HASH_METAPAGE, HASH_READ,
                                    LH_META_PAGE);
        page = BufferGetPage(*metabuf);
 
        /* Populate the cache. */
        if (rel->rd_amcache == NULL)
            rel->rd_amcache = cache;
        memcpy(rel->rd_amcache, HashPageGetMeta(page),
               sizeof(HashMetaPageData));
 
        /* Release metapage lock, but keep the pin. */
        LockBuffer(*metabuf, BUFFER_LOCK_UNLOCK);
    }
 
    return (HashMetaPage) rel->rd_amcache;
}

References _hash_getbuf(), Assert, BUFFER_LOCK_SHARE, BUFFER_LOCK_UNLOCK, BufferGetPage(), BufferIsValid(), fb(), HASH_METAPAGE, HASH_READ, HashPageGetMeta, LH_META_PAGE, LockBuffer(), memcpy(), MemoryContextAlloc(), RelationData::rd_amcache, and RelationData::rd_indexcxt.

Referenced by _hash_getbucketbuf_from_hashkey(), and hashbulkdelete().

_hash_getinitbuf()

Buffer _hash_getinitbuf	(	Relation	rel,
		BlockNumber	blkno
	)

Definition at line 135 of file hashpage.c.

{
    Buffer      buf;
 
    if (blkno == P_NEW)
        elog(ERROR, "hash AM does not use P_NEW");
 
    buf = ReadBufferExtended(rel, MAIN_FORKNUM, blkno, RBM_ZERO_AND_LOCK,
                             NULL);
 
    /* ref count and lock type are correct */
 
    /* initialize the page */
    _hash_pageinit(BufferGetPage(buf), BufferGetPageSize(buf));
 
    return buf;
}

References _hash_pageinit(), buf, BufferGetPage(), BufferGetPageSize(), elog, ERROR, fb(), MAIN_FORKNUM, P_NEW, RBM_ZERO_AND_LOCK, and ReadBufferExtended().

Referenced by _hash_addovflpage().

_hash_getnewbuf()

Buffer _hash_getnewbuf	(	Relation	rel,
		BlockNumber	blkno,
		ForkNumber	forkNum
	)

Definition at line 198 of file hashpage.c.

{
    BlockNumber nblocks = RelationGetNumberOfBlocksInFork(rel, forkNum);
    Buffer      buf;
 
    if (blkno == P_NEW)
        elog(ERROR, "hash AM does not use P_NEW");
    if (blkno > nblocks)
        elog(ERROR, "access to noncontiguous page in hash index \"%s\"",
             RelationGetRelationName(rel));
 
    /* smgr insists we explicitly extend the relation */
    if (blkno == nblocks)
    {
        buf = ExtendBufferedRel(BMR_REL(rel), forkNum, NULL,
                                EB_LOCK_FIRST | EB_SKIP_EXTENSION_LOCK);
        if (BufferGetBlockNumber(buf) != blkno)
            elog(ERROR, "unexpected hash relation size: %u, should be %u",
                 BufferGetBlockNumber(buf), blkno);
    }
    else
    {
        buf = ReadBufferExtended(rel, forkNum, blkno, RBM_ZERO_AND_LOCK,
                                 NULL);
    }
 
    /* ref count and lock type are correct */
 
    /* initialize the page */
    _hash_pageinit(BufferGetPage(buf), BufferGetPageSize(buf));
 
    return buf;
}

References _hash_pageinit(), BMR_REL, buf, BufferGetBlockNumber(), BufferGetPage(), BufferGetPageSize(), EB_LOCK_FIRST, EB_SKIP_EXTENSION_LOCK, elog, ERROR, ExtendBufferedRel(), fb(), P_NEW, RBM_ZERO_AND_LOCK, ReadBufferExtended(), RelationGetNumberOfBlocksInFork(), and RelationGetRelationName.

Referenced by _hash_addovflpage(), _hash_expandtable(), and _hash_init().

_hash_init()

uint32 _hash_init	(	Relation	rel,
		double	num_tuples,
		ForkNumber	forkNum
	)

Definition at line 327 of file hashpage.c.

{
    Buffer      metabuf;
    Buffer      buf;
    Buffer      bitmapbuf;
    Page        pg;
    HashMetaPage metap;
    RegProcedure procid;
    int32       data_width;
    int32       item_width;
    int32       ffactor;
    uint32      num_buckets;
    uint32      i;
    bool        use_wal;
 
    /* safety check */
    if (RelationGetNumberOfBlocksInFork(rel, forkNum) != 0)
        elog(ERROR, "cannot initialize non-empty hash index \"%s\"",
             RelationGetRelationName(rel));
 
    /*
     * WAL log creation of pages if the relation is persistent, or this is the
     * init fork.  Init forks for unlogged relations always need to be WAL
     * logged.
     */
    use_wal = RelationNeedsWAL(rel) || forkNum == INIT_FORKNUM;
 
    /*
     * Determine the target fill factor (in tuples per bucket) for this index.
     * The idea is to make the fill factor correspond to pages about as full
     * as the user-settable fillfactor parameter says.  We can compute it
     * exactly since the index datatype (i.e. uint32 hash key) is fixed-width.
     */
    data_width = sizeof(uint32);
    item_width = MAXALIGN(sizeof(IndexTupleData)) + MAXALIGN(data_width) +
        sizeof(ItemIdData);     /* include the line pointer */
    ffactor = HashGetTargetPageUsage(rel) / item_width;
    /* keep to a sane range */
    if (ffactor < 10)
        ffactor = 10;
 
    procid = index_getprocid(rel, 1, HASHSTANDARD_PROC);
 
    /*
     * We initialize the metapage, the first N bucket pages, and the first
     * bitmap page in sequence, using _hash_getnewbuf to cause smgrextend()
     * calls to occur.  This ensures that the smgr level has the right idea of
     * the physical index length.
     *
     * Critical section not required, because on error the creation of the
     * whole relation will be rolled back.
     */
    metabuf = _hash_getnewbuf(rel, HASH_METAPAGE, forkNum);
    _hash_init_metabuffer(metabuf, num_tuples, procid, ffactor, false);
    MarkBufferDirty(metabuf);
 
    pg = BufferGetPage(metabuf);
    metap = HashPageGetMeta(pg);
 
    /* XLOG stuff */
    if (use_wal)
    {
        xl_hash_init_meta_page xlrec;
        XLogRecPtr  recptr;
 
        xlrec.num_tuples = num_tuples;
        xlrec.procid = metap->hashm_procid;
        xlrec.ffactor = metap->hashm_ffactor;
 
        XLogBeginInsert();
        XLogRegisterData(&xlrec, SizeOfHashInitMetaPage);
        XLogRegisterBuffer(0, metabuf, REGBUF_WILL_INIT | REGBUF_STANDARD);
 
        recptr = XLogInsert(RM_HASH_ID, XLOG_HASH_INIT_META_PAGE);
 
        PageSetLSN(BufferGetPage(metabuf), recptr);
    }
 
    num_buckets = metap->hashm_maxbucket + 1;
 
    /*
     * Release buffer lock on the metapage while we initialize buckets.
     * Otherwise, we'll be in interrupt holdoff and the CHECK_FOR_INTERRUPTS
     * won't accomplish anything.  It's a bad idea to hold buffer locks for
     * long intervals in any case, since that can block the bgwriter.
     */
    LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
 
    /*
     * Initialize and WAL Log the first N buckets
     */
    for (i = 0; i < num_buckets; i++)
    {
        BlockNumber blkno;
 
        /* Allow interrupts, in case N is huge */
        CHECK_FOR_INTERRUPTS();
 
        blkno = BUCKET_TO_BLKNO(metap, i);
        buf = _hash_getnewbuf(rel, blkno, forkNum);
        _hash_initbuf(buf, metap->hashm_maxbucket, i, LH_BUCKET_PAGE, false);
        MarkBufferDirty(buf);
 
        if (use_wal)
            log_newpage(&rel->rd_locator,
                        forkNum,
                        blkno,
                        BufferGetPage(buf),
                        true);
        _hash_relbuf(rel, buf);
    }
 
    /* Now reacquire buffer lock on metapage */
    LockBuffer(metabuf, BUFFER_LOCK_EXCLUSIVE);
 
    /*
     * Initialize bitmap page
     */
    bitmapbuf = _hash_getnewbuf(rel, num_buckets + 1, forkNum);
    _hash_initbitmapbuffer(bitmapbuf, metap->hashm_bmsize, false);
    MarkBufferDirty(bitmapbuf);
 
    /* add the new bitmap page to the metapage's list of bitmaps */
    /* 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))));
 
    metap->hashm_mapp[metap->hashm_nmaps] = num_buckets + 1;
 
    metap->hashm_nmaps++;
    MarkBufferDirty(metabuf);
 
    /* XLOG stuff */
    if (use_wal)
    {
        xl_hash_init_bitmap_page xlrec;
        XLogRecPtr  recptr;
 
        xlrec.bmsize = metap->hashm_bmsize;
 
        XLogBeginInsert();
        XLogRegisterData(&xlrec, SizeOfHashInitBitmapPage);
        XLogRegisterBuffer(0, bitmapbuf, REGBUF_WILL_INIT);
 
        /*
         * This is safe only because nobody else can be modifying the index at
         * this stage; it's only visible to the transaction that is creating
         * it.
         */
        XLogRegisterBuffer(1, metabuf, REGBUF_STANDARD);
 
        recptr = XLogInsert(RM_HASH_ID, XLOG_HASH_INIT_BITMAP_PAGE);
 
        PageSetLSN(BufferGetPage(bitmapbuf), recptr);
        PageSetLSN(BufferGetPage(metabuf), recptr);
    }
 
    /* all done */
    _hash_relbuf(rel, bitmapbuf);
    _hash_relbuf(rel, metabuf);
 
    return num_buckets;
}

References _hash_getnewbuf(), _hash_init_metabuffer(), _hash_initbitmapbuffer(), _hash_initbuf(), _hash_relbuf(), xl_hash_init_bitmap_page::bmsize, BUCKET_TO_BLKNO, buf, BUFFER_LOCK_EXCLUSIVE, BUFFER_LOCK_UNLOCK, BufferGetPage(), CHECK_FOR_INTERRUPTS, elog, ereport, errcode(), errmsg, ERROR, fb(), HASH_MAX_BITMAPS, HASH_METAPAGE, HashGetTargetPageUsage, HashMetaPageData::hashm_bmsize, HashMetaPageData::hashm_ffactor, HashMetaPageData::hashm_mapp, HashMetaPageData::hashm_maxbucket, HashMetaPageData::hashm_nmaps, HashMetaPageData::hashm_procid, HashPageGetMeta, HASHSTANDARD_PROC, i, index_getprocid(), INIT_FORKNUM, LH_BUCKET_PAGE, LockBuffer(), log_newpage(), MarkBufferDirty(), MAXALIGN, xl_hash_init_meta_page::num_tuples, PageSetLSN(), RelationData::rd_locator, REGBUF_STANDARD, REGBUF_WILL_INIT, RelationGetNumberOfBlocksInFork(), RelationGetRelationName, RelationNeedsWAL, SizeOfHashInitBitmapPage, SizeOfHashInitMetaPage, XLOG_HASH_INIT_BITMAP_PAGE, XLOG_HASH_INIT_META_PAGE, XLogBeginInsert(), XLogInsert(), XLogRegisterBuffer(), and XLogRegisterData().

Referenced by hashbuild(), and hashbuildempty().

_hash_init_metabuffer()

void _hash_init_metabuffer	(	Buffer	buf,
		double	num_tuples,
		RegProcedure	procid,
		uint16	ffactor,
		bool	initpage
	)

Definition at line 498 of file hashpage.c.

{
    HashMetaPage metap;
    HashPageOpaque pageopaque;
    Page        page;
    double      dnumbuckets;
    uint32      num_buckets;
    uint32      spare_index;
    uint32      lshift;
 
    /*
     * Choose the number of initial bucket pages to match the fill factor
     * given the estimated number of tuples.  We round up the result to the
     * total number of buckets which has to be allocated before using its
     * hashm_spares element. However always force at least 2 bucket pages. The
     * upper limit is determined by considerations explained in
     * _hash_expandtable().
     */
    dnumbuckets = num_tuples / ffactor;
    if (dnumbuckets <= 2.0)
        num_buckets = 2;
    else if (dnumbuckets >= (double) 0x40000000)
        num_buckets = 0x40000000;
    else
        num_buckets = _hash_get_totalbuckets(_hash_spareindex(dnumbuckets));
 
    spare_index = _hash_spareindex(num_buckets);
    Assert(spare_index < HASH_MAX_SPLITPOINTS);
 
    page = BufferGetPage(buf);
    if (initpage)
        _hash_pageinit(page, BufferGetPageSize(buf));
 
    pageopaque = HashPageGetOpaque(page);
    pageopaque->hasho_prevblkno = InvalidBlockNumber;
    pageopaque->hasho_nextblkno = InvalidBlockNumber;
    pageopaque->hasho_bucket = InvalidBucket;
    pageopaque->hasho_flag = LH_META_PAGE;
    pageopaque->hasho_page_id = HASHO_PAGE_ID;
 
    metap = HashPageGetMeta(page);
 
    metap->hashm_magic = HASH_MAGIC;
    metap->hashm_version = HASH_VERSION;
    metap->hashm_ntuples = 0;
    metap->hashm_nmaps = 0;
    metap->hashm_ffactor = ffactor;
    metap->hashm_bsize = HashGetMaxBitmapSize(page);
 
    /* find largest bitmap array size that will fit in page size */
    lshift = pg_leftmost_one_pos32(metap->hashm_bsize);
    Assert(lshift > 0);
    metap->hashm_bmsize = 1 << lshift;
    metap->hashm_bmshift = lshift + BYTE_TO_BIT;
    Assert((1 << BMPG_SHIFT(metap)) == (BMPG_MASK(metap) + 1));
 
    /*
     * Label the index with its primary hash support function's OID.  This is
     * pretty useless for normal operation (in fact, hashm_procid is not used
     * anywhere), but it might be handy for forensic purposes so we keep it.
     */
    metap->hashm_procid = procid;
 
    /*
     * We initialize the index with N buckets, 0 .. N-1, occupying physical
     * blocks 1 to N.  The first freespace bitmap page is in block N+1.
     */
    metap->hashm_maxbucket = num_buckets - 1;
 
    /*
     * Set highmask as next immediate ((2 ^ x) - 1), which should be
     * sufficient to cover num_buckets.
     */
    metap->hashm_highmask = pg_nextpower2_32(num_buckets + 1) - 1;
    metap->hashm_lowmask = (metap->hashm_highmask >> 1);
 
    MemSet(metap->hashm_spares, 0, sizeof(metap->hashm_spares));
    MemSet(metap->hashm_mapp, 0, sizeof(metap->hashm_mapp));
 
    /* Set up mapping for one spare page after the initial splitpoints */
    metap->hashm_spares[spare_index] = 1;
    metap->hashm_ovflpoint = spare_index;
    metap->hashm_firstfree = 0;
 
    /*
     * Set pd_lower just past the end of the metadata.  This is essential,
     * because without doing so, metadata will be lost if xlog.c compresses
     * the page.
     */
    ((PageHeader) page)->pd_lower =
        ((char *) metap + sizeof(HashMetaPageData)) - (char *) page;
}

References _hash_get_totalbuckets(), _hash_pageinit(), _hash_spareindex(), Assert, BMPG_MASK, BMPG_SHIFT, buf, BufferGetPage(), BufferGetPageSize(), BYTE_TO_BIT, fb(), HASH_MAGIC, HASH_MAX_SPLITPOINTS, HASH_VERSION, HashGetMaxBitmapSize, HashMetaPageData::hashm_bmshift, HashMetaPageData::hashm_bmsize, HashMetaPageData::hashm_bsize, HashMetaPageData::hashm_ffactor, HashMetaPageData::hashm_firstfree, HashMetaPageData::hashm_highmask, HashMetaPageData::hashm_lowmask, HashMetaPageData::hashm_magic, HashMetaPageData::hashm_mapp, HashMetaPageData::hashm_maxbucket, HashMetaPageData::hashm_nmaps, HashMetaPageData::hashm_ntuples, HashMetaPageData::hashm_ovflpoint, HashMetaPageData::hashm_procid, HashMetaPageData::hashm_spares, HashMetaPageData::hashm_version, HASHO_PAGE_ID, HashPageGetMeta, HashPageGetOpaque, InvalidBlockNumber, InvalidBucket, LH_META_PAGE, MemSet, pg_leftmost_one_pos32(), and pg_nextpower2_32().

Referenced by _hash_init(), and hash_xlog_init_meta_page().

_hash_initbuf()

void _hash_initbuf	(	Buffer	buf,
		uint32	max_bucket,
		uint32	num_bucket,
		uint32	flag,
		bool	initpage
	)

Definition at line 157 of file hashpage.c.

{
    HashPageOpaque pageopaque;
    Page        page;
 
    page = BufferGetPage(buf);
 
    /* initialize the page */
    if (initpage)
        _hash_pageinit(page, BufferGetPageSize(buf));
 
    pageopaque = HashPageGetOpaque(page);
 
    /*
     * Set hasho_prevblkno with current hashm_maxbucket. This value will be
     * used to validate cached HashMetaPageData. See
     * _hash_getbucketbuf_from_hashkey().
     */
    pageopaque->hasho_prevblkno = max_bucket;
    pageopaque->hasho_nextblkno = InvalidBlockNumber;
    pageopaque->hasho_bucket = num_bucket;
    pageopaque->hasho_flag = flag;
    pageopaque->hasho_page_id = HASHO_PAGE_ID;
}

References _hash_pageinit(), buf, BufferGetPage(), BufferGetPageSize(), fb(), flag(), HASHO_PAGE_ID, HashPageGetOpaque, and InvalidBlockNumber.

Referenced by _hash_init(), hash_xlog_add_ovfl_page(), and hash_xlog_split_allocate_page().

_hash_pageinit()

void _hash_pageinit	(	Page	page,
		Size	size
	)

Definition at line 596 of file hashpage.c.

{
    PageInit(page, size, sizeof(HashPageOpaqueData));
}

References PageInit().

Referenced by _hash_alloc_buckets(), _hash_freeovflpage(), _hash_getinitbuf(), _hash_getnewbuf(), _hash_init_metabuffer(), _hash_initbitmapbuffer(), _hash_initbuf(), and hash_xlog_squeeze_page().

_hash_relbuf()

void _hash_relbuf	(	Relation	rel,
		Buffer	buf
	)

Definition at line 266 of file hashpage.c.

{
    UnlockReleaseBuffer(buf);
}

References buf, and UnlockReleaseBuffer().

Referenced by _hash_addovflpage(), _hash_doinsert(), _hash_expandtable(), _hash_finish_split(), _hash_freeovflpage(), _hash_get_newblock_from_oldbucket(), _hash_get_oldblock_from_newbucket(), _hash_getbucketbuf_from_hashkey(), _hash_init(), _hash_kill_items(), _hash_readnext(), _hash_readpage(), _hash_readprev(), _hash_splitbucket(), _hash_squeezebucket(), hash_bitmap_info(), hashbucketcleanup(), hashbulkdelete(), pgstat_hash_page(), and pgstathashindex().

_hash_splitbucket()

static void _hash_splitbucket ( Relation  rel, Buffer  metabuf, Bucket  obucket, Bucket  nbucket, Buffer  obuf, Buffer  nbuf, HTAB *  htab, uint32  maxbucket, uint32  highmask, uint32  lowmask  )

static

Definition at line 1075 of file hashpage.c.

{
    Buffer      bucket_obuf;
    Buffer      bucket_nbuf;
    Page        opage;
    Page        npage;
    HashPageOpaque oopaque;
    HashPageOpaque nopaque;
    OffsetNumber itup_offsets[MaxIndexTuplesPerPage];
    IndexTuple  itups[MaxIndexTuplesPerPage];
    Size        all_tups_size = 0;
    int         i;
    uint16      nitups = 0;
    XLogRecPtr  recptr;
 
    bucket_obuf = obuf;
    opage = BufferGetPage(obuf);
    oopaque = HashPageGetOpaque(opage);
 
    bucket_nbuf = nbuf;
    npage = BufferGetPage(nbuf);
    nopaque = HashPageGetOpaque(npage);
 
    /* Copy the predicate locks from old bucket to new bucket. */
    PredicateLockPageSplit(rel,
                           BufferGetBlockNumber(bucket_obuf),
                           BufferGetBlockNumber(bucket_nbuf));
 
    /*
     * Partition the tuples in the old bucket between the old bucket and the
     * new bucket, advancing along the old bucket's overflow bucket chain and
     * adding overflow pages to the new bucket as needed.  Outer loop iterates
     * once per page in old bucket.
     */
    for (;;)
    {
        BlockNumber oblkno;
        OffsetNumber ooffnum;
        OffsetNumber omaxoffnum;
 
        /* Scan each tuple in old page */
        omaxoffnum = PageGetMaxOffsetNumber(opage);
        for (ooffnum = FirstOffsetNumber;
             ooffnum <= omaxoffnum;
             ooffnum = OffsetNumberNext(ooffnum))
        {
            IndexTuple  itup;
            Size        itemsz;
            Bucket      bucket;
            bool        found = false;
 
            /* skip dead tuples */
            if (ItemIdIsDead(PageGetItemId(opage, ooffnum)))
                continue;
 
            /*
             * Before inserting a tuple, probe the hash table containing TIDs
             * of tuples belonging to new bucket, if we find a match, then
             * skip that tuple, else fetch the item's hash key (conveniently
             * stored in the item) and determine which bucket it now belongs
             * in.
             */
            itup = (IndexTuple) PageGetItem(opage,
                                            PageGetItemId(opage, ooffnum));
 
            if (htab)
                (void) hash_search(htab, &itup->t_tid, HASH_FIND, &found);
 
            if (found)
                continue;
 
            bucket = _hash_hashkey2bucket(_hash_get_indextuple_hashkey(itup),
                                          maxbucket, highmask, lowmask);
 
            if (bucket == nbucket)
            {
                IndexTuple  new_itup;
 
                /*
                 * make a copy of index tuple as we have to scribble on it.
                 */
                new_itup = CopyIndexTuple(itup);
 
                /*
                 * mark the index tuple as moved by split, such tuples are
                 * skipped by scan if there is split in progress for a bucket.
                 */
                new_itup->t_info |= INDEX_MOVED_BY_SPLIT_MASK;
 
                /*
                 * insert the tuple into the new bucket.  if it doesn't fit on
                 * the current page in the new bucket, we must allocate a new
                 * overflow page and place the tuple on that page instead.
                 */
                itemsz = IndexTupleSize(new_itup);
                itemsz = MAXALIGN(itemsz);
 
                if (PageGetFreeSpaceForMultipleTuples(npage, nitups + 1) < (all_tups_size + itemsz))
                {
                    /*
                     * Change the shared buffer state in critical section,
                     * otherwise any error could make it unrecoverable.
                     */
                    START_CRIT_SECTION();
 
                    _hash_pgaddmultitup(rel, nbuf, itups, itup_offsets, nitups);
                    MarkBufferDirty(nbuf);
                    /* log the split operation before releasing the lock */
                    log_split_page(rel, nbuf);
 
                    END_CRIT_SECTION();
 
                    /* drop lock, but keep pin */
                    LockBuffer(nbuf, BUFFER_LOCK_UNLOCK);
 
                    /* be tidy */
                    for (i = 0; i < nitups; i++)
                        pfree(itups[i]);
                    nitups = 0;
                    all_tups_size = 0;
 
                    /* chain to a new overflow page */
                    nbuf = _hash_addovflpage(rel, metabuf, nbuf, (nbuf == bucket_nbuf));
                    npage = BufferGetPage(nbuf);
                    nopaque = HashPageGetOpaque(npage);
                }
 
                itups[nitups++] = new_itup;
                all_tups_size += itemsz;
            }
            else
            {
                /*
                 * the tuple stays on this page, so nothing to do.
                 */
                Assert(bucket == obucket);
            }
        }
 
        oblkno = oopaque->hasho_nextblkno;
 
        /* retain the pin on the old primary bucket */
        if (obuf == bucket_obuf)
            LockBuffer(obuf, BUFFER_LOCK_UNLOCK);
        else
            _hash_relbuf(rel, obuf);
 
        /* Exit loop if no more overflow pages in old bucket */
        if (!BlockNumberIsValid(oblkno))
        {
            /*
             * Change the shared buffer state in critical section, otherwise
             * any error could make it unrecoverable.
             */
            START_CRIT_SECTION();
 
            _hash_pgaddmultitup(rel, nbuf, itups, itup_offsets, nitups);
            MarkBufferDirty(nbuf);
            /* log the split operation before releasing the lock */
            log_split_page(rel, nbuf);
 
            END_CRIT_SECTION();
 
            if (nbuf == bucket_nbuf)
                LockBuffer(nbuf, BUFFER_LOCK_UNLOCK);
            else
                _hash_relbuf(rel, nbuf);
 
            /* be tidy */
            for (i = 0; i < nitups; i++)
                pfree(itups[i]);
            break;
        }
 
        /* Else, advance to next old page */
        obuf = _hash_getbuf(rel, oblkno, HASH_READ, LH_OVERFLOW_PAGE);
        opage = BufferGetPage(obuf);
        oopaque = HashPageGetOpaque(opage);
    }
 
    /*
     * We're at the end of the old bucket chain, so we're done partitioning
     * the tuples.  Mark the old and new buckets to indicate split is
     * finished.
     *
     * To avoid deadlocks due to locking order of buckets, first lock the old
     * bucket and then the new bucket.
     */
    LockBuffer(bucket_obuf, BUFFER_LOCK_EXCLUSIVE);
    opage = BufferGetPage(bucket_obuf);
    oopaque = HashPageGetOpaque(opage);
 
    LockBuffer(bucket_nbuf, BUFFER_LOCK_EXCLUSIVE);
    npage = BufferGetPage(bucket_nbuf);
    nopaque = HashPageGetOpaque(npage);
 
    START_CRIT_SECTION();
 
    oopaque->hasho_flag &= ~LH_BUCKET_BEING_SPLIT;
    nopaque->hasho_flag &= ~LH_BUCKET_BEING_POPULATED;
 
    /*
     * After the split is finished, mark the old bucket to indicate that it
     * contains deletable tuples.  We will clear split-cleanup flag after
     * deleting such tuples either at the end of split or at the next split
     * from old bucket or at the time of vacuum.
     */
    oopaque->hasho_flag |= LH_BUCKET_NEEDS_SPLIT_CLEANUP;
 
    /*
     * now write the buffers, here we don't release the locks as caller is
     * responsible to release locks.
     */
    MarkBufferDirty(bucket_obuf);
    MarkBufferDirty(bucket_nbuf);
 
    if (RelationNeedsWAL(rel))
    {
        xl_hash_split_complete xlrec;
 
        xlrec.old_bucket_flag = oopaque->hasho_flag;
        xlrec.new_bucket_flag = nopaque->hasho_flag;
 
        XLogBeginInsert();
 
        XLogRegisterData(&xlrec, SizeOfHashSplitComplete);
 
        XLogRegisterBuffer(0, bucket_obuf, REGBUF_STANDARD);
        XLogRegisterBuffer(1, bucket_nbuf, REGBUF_STANDARD);
 
        recptr = XLogInsert(RM_HASH_ID, XLOG_HASH_SPLIT_COMPLETE);
    }
    else
        recptr = XLogGetFakeLSN(rel);
 
    PageSetLSN(BufferGetPage(bucket_obuf), recptr);
    PageSetLSN(BufferGetPage(bucket_nbuf), recptr);
 
    END_CRIT_SECTION();
 
    /*
     * If possible, clean up the old bucket.  We might not be able to do this
     * if someone else has a pin on it, but if not then we can go ahead.  This
     * isn't absolutely necessary, but it reduces bloat; if we don't do it
     * now, VACUUM will do it eventually, but maybe not until new overflow
     * pages have been allocated.  Note that there's no need to clean up the
     * new bucket.
     */
    if (IsBufferCleanupOK(bucket_obuf))
    {
        LockBuffer(bucket_nbuf, BUFFER_LOCK_UNLOCK);
        hashbucketcleanup(rel, obucket, bucket_obuf,
                          BufferGetBlockNumber(bucket_obuf), NULL,
                          maxbucket, highmask, lowmask, NULL, NULL, true,
                          NULL, NULL);
    }
    else
    {
        LockBuffer(bucket_nbuf, BUFFER_LOCK_UNLOCK);
        LockBuffer(bucket_obuf, BUFFER_LOCK_UNLOCK);
    }
}

References _hash_addovflpage(), _hash_get_indextuple_hashkey(), _hash_getbuf(), _hash_hashkey2bucket(), _hash_pgaddmultitup(), _hash_relbuf(), Assert, BlockNumberIsValid(), BUFFER_LOCK_EXCLUSIVE, BUFFER_LOCK_UNLOCK, BufferGetBlockNumber(), BufferGetPage(), CopyIndexTuple(), END_CRIT_SECTION, fb(), FirstOffsetNumber, HASH_FIND, HASH_READ, hash_search(), hashbucketcleanup(), HashPageGetOpaque, i, INDEX_MOVED_BY_SPLIT_MASK, IndexTupleSize(), IsBufferCleanupOK(), ItemIdIsDead, LH_BUCKET_NEEDS_SPLIT_CLEANUP, LH_OVERFLOW_PAGE, LockBuffer(), log_split_page(), MarkBufferDirty(), MAXALIGN, MaxIndexTuplesPerPage, OffsetNumberNext, xl_hash_split_complete::old_bucket_flag, PageGetFreeSpaceForMultipleTuples(), PageGetItem(), PageGetItemId(), PageGetMaxOffsetNumber(), PageSetLSN(), pfree(), PredicateLockPageSplit(), REGBUF_STANDARD, RelationNeedsWAL, SizeOfHashSplitComplete, START_CRIT_SECTION, IndexTupleData::t_tid, XLOG_HASH_SPLIT_COMPLETE, XLogBeginInsert(), XLogGetFakeLSN(), XLogInsert(), XLogRegisterBuffer(), and XLogRegisterData().

Referenced by _hash_expandtable(), and _hash_finish_split().

log_split_page()

static void log_split_page ( Relation  rel, Buffer  buf  )

static

Definition at line 1478 of file hashpage.c.

{
    if (RelationNeedsWAL(rel))
    {
        XLogRecPtr  recptr;
 
        XLogBeginInsert();
 
        XLogRegisterBuffer(0, buf, REGBUF_FORCE_IMAGE | REGBUF_STANDARD);
 
        recptr = XLogInsert(RM_HASH_ID, XLOG_HASH_SPLIT_PAGE);
 
        PageSetLSN(BufferGetPage(buf), recptr);
    }
}

References buf, BufferGetPage(), fb(), PageSetLSN(), REGBUF_FORCE_IMAGE, REGBUF_STANDARD, RelationNeedsWAL, XLOG_HASH_SPLIT_PAGE, XLogBeginInsert(), XLogInsert(), and XLogRegisterBuffer().

Referenced by _hash_splitbucket().