* hashpage.c
* Hash table page management code for the Postgres hash access method
*
- * Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
#include "postgres.h"
#include "access/hash.h"
+#include "access/hash_xlog.h"
#include "miscadmin.h"
#include "storage/lmgr.h"
#include "storage/smgr.h"
+#include "storage/predicate.h"
static bool _hash_alloc_buckets(Relation rel, BlockNumber firstblock,
Bucket obucket, Bucket nbucket,
Buffer obuf,
Buffer nbuf,
+ HTAB *htab,
uint32 maxbucket,
uint32 highmask, uint32 lowmask);
-static void _hash_splitbucket_guts(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);
/*
return buf;
}
+/*
+ * _hash_initbuf() -- Get and initialize a buffer by bucket number.
+ */
+void
+_hash_initbuf(Buffer buf, uint32 max_bucket, uint32 num_bucket, uint32 flag,
+ bool initpage)
+{
+ HashPageOpaque pageopaque;
+ Page page;
+
+ page = BufferGetPage(buf);
+
+ /* initialize the page */
+ if (initpage)
+ _hash_pageinit(page, BufferGetPageSize(buf));
+
+ pageopaque = (HashPageOpaque) PageGetSpecialPointer(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;
+}
+
/*
* _hash_getnewbuf() -- Get a new page at the end of the index.
*
{
/* release pin we hold on primary bucket page */
if (BufferIsValid(so->hashso_bucket_buf) &&
- so->hashso_bucket_buf != so->hashso_curbuf)
+ 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->hashso_curbuf)
+ 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->hashso_curbuf))
- _hash_dropbuf(rel, so->hashso_curbuf);
- so->hashso_curbuf = InvalidBuffer;
+ 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;
}
-/*
- * _hash_wrtbuf() -- write a hash page to disk.
- *
- * This routine releases the lock held on the buffer and our refcount
- * for it. It is an error to call _hash_wrtbuf() without a write lock
- * and a pin on the buffer.
- *
- * NOTE: this routine should go away when/if hash indexes are WAL-ified.
- * The correct sequence of operations is to mark the buffer dirty, then
- * write the WAL record, then release the lock and pin; so marking dirty
- * can't be combined with releasing.
- */
-void
-_hash_wrtbuf(Relation rel, Buffer buf)
-{
- MarkBufferDirty(buf);
- UnlockReleaseBuffer(buf);
-}
/*
- * _hash_chgbufaccess() -- Change the lock type on a buffer, without
- * dropping our pin on it.
- *
- * from_access and to_access may be HASH_READ, HASH_WRITE, or HASH_NOLOCK,
- * the last indicating that no buffer-level lock is held or wanted.
- *
- * When from_access == HASH_WRITE, we assume the buffer is dirty and tell
- * bufmgr it must be written out. If the caller wants to release a write
- * lock on a page that's not been modified, it's okay to pass from_access
- * as HASH_READ (a bit ugly, but handy in some places).
- */
-void
-_hash_chgbufaccess(Relation rel,
- Buffer buf,
- int from_access,
- int to_access)
-{
- if (from_access == HASH_WRITE)
- MarkBufferDirty(buf);
- if (from_access != HASH_NOLOCK)
- LockBuffer(buf, BUFFER_LOCK_UNLOCK);
- if (to_access != HASH_NOLOCK)
- LockBuffer(buf, to_access);
-}
-
-
-/*
- * _hash_metapinit() -- Initialize the metadata page of a hash index,
+ * _hash_init() -- Initialize the metadata page of a hash index,
* the initial buckets, and the initial bitmap page.
*
* The initial number of buckets is dependent on num_tuples, an estimate
* multiple buffer locks is ignored.
*/
uint32
-_hash_metapinit(Relation rel, double num_tuples, ForkNumber forkNum)
+_hash_init(Relation rel, double num_tuples, ForkNumber forkNum)
{
- HashMetaPage metap;
- HashPageOpaque pageopaque;
Buffer metabuf;
Buffer buf;
+ Buffer bitmapbuf;
Page pg;
+ HashMetaPage metap;
+ RegProcedure procid;
int32 data_width;
int32 item_width;
int32 ffactor;
- double dnumbuckets;
uint32 num_buckets;
- uint32 log2_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
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((char *) &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_node,
+ 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((char *) &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;
+}
+
+/*
+ * _hash_init_metabuffer() -- Initialize the metadata page of a hash index.
+ */
+void
+_hash_init_metabuffer(Buffer buf, double num_tuples, RegProcedure procid,
+ uint16 ffactor, bool initpage)
+{
+ HashMetaPage metap;
+ HashPageOpaque pageopaque;
+ Page page;
+ double dnumbuckets;
+ uint32 num_buckets;
+ uint32 spare_index;
+ uint32 i;
+
/*
* 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
- * next power of 2, however, and always force at least 2 bucket pages. The
+ * total number of buckets which has to be allocated before using its
+ * _hashm_spare element. However always force at least 2 bucket pages. The
* upper limit is determined by considerations explained in
* _hash_expandtable().
*/
else if (dnumbuckets >= (double) 0x40000000)
num_buckets = 0x40000000;
else
- num_buckets = ((uint32) 1) << _hash_log2((uint32) dnumbuckets);
+ num_buckets = _hash_get_totalbuckets(_hash_spareindex(dnumbuckets));
- log2_num_buckets = _hash_log2(num_buckets);
- Assert(num_buckets == (((uint32) 1) << log2_num_buckets));
- Assert(log2_num_buckets < HASH_MAX_SPLITPOINTS);
+ spare_index = _hash_spareindex(num_buckets);
+ Assert(spare_index < HASH_MAX_SPLITPOINTS);
- /*
- * 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.
- */
- metabuf = _hash_getnewbuf(rel, HASH_METAPAGE, forkNum);
- pg = BufferGetPage(metabuf);
+ page = BufferGetPage(buf);
+ if (initpage)
+ _hash_pageinit(page, BufferGetPageSize(buf));
- pageopaque = (HashPageOpaque) PageGetSpecialPointer(pg);
+ pageopaque = (HashPageOpaque) PageGetSpecialPointer(page);
pageopaque->hasho_prevblkno = InvalidBlockNumber;
pageopaque->hasho_nextblkno = InvalidBlockNumber;
pageopaque->hasho_bucket = -1;
pageopaque->hasho_flag = LH_META_PAGE;
pageopaque->hasho_page_id = HASHO_PAGE_ID;
- metap = HashPageGetMeta(pg);
+ 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(pg);
+ metap->hashm_bsize = HashGetMaxBitmapSize(page);
/* find largest bitmap array size that will fit in page size */
for (i = _hash_log2(metap->hashm_bsize); i > 0; --i)
{
* 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 = index_getprocid(rel, 1, HASHPROC);
+ 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. Since
- * N is a power of 2, we can set the masks this way:
+ * 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_maxbucket = metap->hashm_lowmask = num_buckets - 1;
- metap->hashm_highmask = (num_buckets << 1) - 1;
+ metap->hashm_highmask = (1 << (_hash_log2(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[log2_num_buckets] = 1;
- metap->hashm_ovflpoint = log2_num_buckets;
+ metap->hashm_spares[spare_index] = 1;
+ metap->hashm_ovflpoint = spare_index;
metap->hashm_firstfree = 0;
/*
- * 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.
- */
- _hash_chgbufaccess(rel, metabuf, HASH_WRITE, HASH_NOLOCK);
-
- /*
- * Initialize the first N buckets
- */
- for (i = 0; i < num_buckets; i++)
- {
- /* Allow interrupts, in case N is huge */
- CHECK_FOR_INTERRUPTS();
-
- buf = _hash_getnewbuf(rel, BUCKET_TO_BLKNO(metap, i), forkNum);
- pg = BufferGetPage(buf);
- pageopaque = (HashPageOpaque) PageGetSpecialPointer(pg);
- pageopaque->hasho_prevblkno = InvalidBlockNumber;
- pageopaque->hasho_nextblkno = InvalidBlockNumber;
- pageopaque->hasho_bucket = i;
- pageopaque->hasho_flag = LH_BUCKET_PAGE;
- pageopaque->hasho_page_id = HASHO_PAGE_ID;
- _hash_wrtbuf(rel, buf);
- }
-
- /* Now reacquire buffer lock on metapage */
- _hash_chgbufaccess(rel, metabuf, HASH_NOLOCK, HASH_WRITE);
-
- /*
- * Initialize first bitmap page
+ * 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.
*/
- _hash_initbitmap(rel, metap, num_buckets + 1, forkNum);
-
- /* all done */
- _hash_wrtbuf(rel, metabuf);
-
- return num_buckets;
+ ((PageHeader) page)->pd_lower =
+ ((char *) metap + sizeof(HashMetaPageData)) - (char *) page;
}
/*
void
_hash_pageinit(Page page, Size size)
{
- Assert(PageIsNew(page));
PageInit(page, size, sizeof(HashPageOpaqueData));
}
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;
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.
*/
- _hash_chgbufaccess(rel, metabuf, HASH_NOLOCK, HASH_WRITE);
+ LockBuffer(metabuf, BUFFER_LOCK_EXCLUSIVE);
_hash_checkpage(rel, metabuf, LH_META_PAGE);
metap = HashPageGetMeta(BufferGetPage(metabuf));
* 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_metapinit().
+ * _hash_init().
*/
if (metap->hashm_maxbucket >= (uint32) 0x7FFFFFFE)
goto fail;
* Release the lock on metapage and old_bucket, before completing the
* split.
*/
- _hash_chgbufaccess(rel, metabuf, HASH_READ, HASH_NOLOCK);
- _hash_chgbufaccess(rel, buf_oblkno, HASH_READ, HASH_NOLOCK);
+ LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
+ LockBuffer(buf_oblkno, BUFFER_LOCK_UNLOCK);
_hash_finish_split(rel, metabuf, buf_oblkno, old_bucket, maxbucket,
highmask, lowmask);
{
/*
* 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.
+ * 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. */
- _hash_chgbufaccess(rel, metabuf, HASH_READ, HASH_NOLOCK);
+ LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
hashbucketcleanup(rel, old_bucket, buf_oblkno, start_oblkno, NULL,
maxbucket, highmask, lowmask, NULL, NULL, true,
start_nblkno = BUCKET_TO_BLKNO(metap, new_bucket);
/*
- * If the split point is increasing (hashm_maxbucket's log base 2
- * increases), we need to allocate a new batch of bucket pages.
+ * If the split point is increasing we need to allocate a new batch of
+ * bucket pages.
*/
- spare_ndx = _hash_log2(new_bucket + 1);
+ spare_ndx = _hash_spareindex(new_bucket + 1);
if (spare_ndx > metap->hashm_ovflpoint)
{
+ uint32 buckets_to_add;
+
Assert(spare_ndx == metap->hashm_ovflpoint + 1);
/*
- * The number of buckets in the new splitpoint is equal to the total
- * number already in existence, i.e. new_bucket. Currently this maps
- * one-to-one to blocks required, but someday we may need a more
- * complicated calculation here.
+ * 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.
*/
- if (!_hash_alloc_buckets(rel, start_nblkno, new_bucket))
+ 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;
}
-
/*
- * Okay to proceed with split. Update the metapage bucket mapping info.
- *
- * Since we are scribbling on the metapage data right in the shared
- * buffer, any failure in this next little bit leaves us with a big
+ * 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. We don't really expect any failure, but just to be sure,
- * establish a critical section.
+ * 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 (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.
+ * 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;
}
- /* Done mucking with metapage */
- END_CRIT_SECTION();
+ MarkBufferDirty(metabuf);
/*
* Copy bucket mapping info now; this saves re-accessing the meta page
highmask = metap->hashm_highmask;
lowmask = metap->hashm_lowmask;
- /* Write out the metapage and drop lock, but keep pin */
- _hash_chgbufaccess(rel, metabuf, HASH_WRITE, HASH_NOLOCK);
+ opage = BufferGetPage(buf_oblkno);
+ oopaque = (HashPageOpaque) PageGetSpecialPointer(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 = (HashPageOpaque) PageGetSpecialPointer(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;
+ XLogRecPtr recptr;
+
+ 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, (char *) &metap->hashm_lowmask, sizeof(uint32));
+ XLogRegisterBufData(2, (char *) &metap->hashm_highmask, sizeof(uint32));
+ }
+
+ if (metap_update_splitpoint)
+ {
+ xlrec.flags |= XLH_SPLIT_META_UPDATE_SPLITPOINT;
+ XLogRegisterBufData(2, (char *) &metap->hashm_ovflpoint,
+ sizeof(uint32));
+ XLogRegisterBufData(2,
+ (char *) &metap->hashm_spares[metap->hashm_ovflpoint],
+ sizeof(uint32));
+ }
+
+ XLogRegisterData((char *) &xlrec, SizeOfHashSplitAllocPage);
+
+ recptr = XLogInsert(RM_HASH_ID, XLOG_HASH_SPLIT_ALLOCATE_PAGE);
+
+ 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,
+ 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 */
- _hash_chgbufaccess(rel, metabuf, HASH_READ, HASH_NOLOCK);
+ LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
}
* hash indexes sequentially anyway, that probably doesn't matter.
*
* XXX It's annoying that this code is executed with the metapage lock held.
- * We need to interlock against _hash_getovflpage() adding a new overflow page
+ * We need to interlock against _hash_addovflpage() adding a new overflow page
* concurrently, but it'd likely be better to use LockRelationForExtension
* for the purpose. OTOH, adding a splitpoint is a very infrequent operation,
* so it may not be worth worrying about.
*
- * Returns TRUE if successful, or FALSE if allocation failed due to
+ * Returns true if successful, or false if allocation failed due to
* BlockNumber overflow.
*/
static bool
_hash_alloc_buckets(Relation rel, BlockNumber firstblock, uint32 nblocks)
{
BlockNumber lastblock;
- char zerobuf[BLCKSZ];
+ PGAlignedBlock zerobuf;
+ Page page;
+ HashPageOpaque ovflopaque;
lastblock = firstblock + nblocks - 1;
if (lastblock < firstblock || lastblock == InvalidBlockNumber)
return false;
- MemSet(zerobuf, 0, sizeof(zerobuf));
+ 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 = (HashPageOpaque) PageGetSpecialPointer(page);
+
+ ovflopaque->hasho_prevblkno = InvalidBlockNumber;
+ ovflopaque->hasho_nextblkno = InvalidBlockNumber;
+ ovflopaque->hasho_bucket = -1;
+ ovflopaque->hasho_flag = LH_UNUSED_PAGE;
+ ovflopaque->hasho_page_id = HASHO_PAGE_ID;
+
+ if (RelationNeedsWAL(rel))
+ log_newpage(&rel->rd_node,
+ MAIN_FORKNUM,
+ lastblock,
+ zerobuf.data,
+ true);
RelationOpenSmgr(rel);
- smgrextend(rel->rd_smgr, MAIN_FORKNUM, lastblock, zerobuf, false);
+ PageSetChecksumInplace(page, lastblock);
+ smgrextend(rel->rd_smgr, MAIN_FORKNUM, lastblock, zerobuf.data, false);
return true;
}
/*
* _hash_splitbucket -- split 'obucket' into 'obucket' and 'nbucket'
*
+ * This routine is used to partition the tuples between old and new bucket and
+ * is used to finish the incomplete split operations. To finish the previously
+ * interrupted split operation, the caller needs to fill htab. If htab is set,
+ * then we skip the movement of tuples that exists in htab, otherwise NULL
+ * value of htab indicates movement of all the tuples that belong to the new
+ * bucket.
+ *
* 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.
+ * belong in the new bucket.
*
* The caller must hold cleanup locks on both buckets to ensure that
* no one else is trying to access them (see README).
* while a split is in progress.
*
* In addition, the caller must have created the new bucket's base page,
- * which is passed in buffer nbuf, pinned and write-locked. That lock and
- * pin are released here. (The API is set up this way because we must do
- * _hash_getnewbuf() before releasing the metapage write lock. So instead of
- * passing the new bucket's start block number, we pass an actual buffer.)
+ * which is passed in buffer nbuf, pinned and write-locked. The lock will be
+ * released here and pin must be released by the caller. (The API is set up
+ * this way because we must do _hash_getnewbuf() before releasing the metapage
+ * write lock. So instead of passing the new bucket's start block number, we
+ * pass an actual buffer.)
*/
static void
_hash_splitbucket(Relation rel,
Bucket nbucket,
Buffer obuf,
Buffer nbuf,
+ HTAB *htab,
uint32 maxbucket,
uint32 highmask,
uint32 lowmask)
-{
- Page opage;
- Page npage;
- HashPageOpaque oopaque;
- HashPageOpaque nopaque;
-
- opage = BufferGetPage(obuf);
- oopaque = (HashPageOpaque) PageGetSpecialPointer(opage);
-
- /*
- * Mark the old bucket to indicate that split is in progress. At
- * operation end, we clear split-in-progress flag.
- */
- oopaque->hasho_flag |= LH_BUCKET_BEING_SPLIT;
-
- npage = BufferGetPage(nbuf);
-
- /*
- * initialize the new bucket's primary page and mark it to indicate that
- * split is in progress.
- */
- nopaque = (HashPageOpaque) PageGetSpecialPointer(npage);
- nopaque->hasho_prevblkno = InvalidBlockNumber;
- nopaque->hasho_nextblkno = InvalidBlockNumber;
- nopaque->hasho_bucket = nbucket;
- nopaque->hasho_flag = LH_BUCKET_PAGE | LH_BUCKET_BEING_POPULATED;
- nopaque->hasho_page_id = HASHO_PAGE_ID;
-
- _hash_splitbucket_guts(rel, metabuf, obucket,
- nbucket, obuf, nbuf, NULL,
- maxbucket, highmask, lowmask);
-
- /* all done, now release the locks and pins on primary buckets. */
- _hash_relbuf(rel, obuf);
- _hash_relbuf(rel, nbuf);
-}
-
-/*
- * _hash_splitbucket_guts -- Helper function to perform the split operation
- *
- * This routine is used to partition the tuples between old and new bucket and
- * to finish incomplete split operations. To finish the previously
- * interrupted split operation, caller needs to fill htab. If htab is set, then
- * we skip the movement of tuples that exists in htab, otherwise NULL value of
- * htab indicates movement of all the tuples that belong to new bucket.
- *
- * Caller needs to lock and unlock the old and new primary buckets.
- */
-static void
-_hash_splitbucket_guts(Relation rel,
- Buffer metabuf,
- Bucket obucket,
- Bucket nbucket,
- Buffer obuf,
- Buffer nbuf,
- HTAB *htab,
- uint32 maxbucket,
- uint32 highmask,
- uint32 lowmask)
{
Buffer bucket_obuf;
Buffer bucket_nbuf;
Page npage;
HashPageOpaque oopaque;
HashPageOpaque nopaque;
+ OffsetNumber itup_offsets[MaxIndexTuplesPerPage];
+ IndexTuple itups[MaxIndexTuplesPerPage];
+ Size all_tups_size = 0;
+ int i;
+ uint16 nitups = 0;
bucket_obuf = obuf;
opage = BufferGetPage(obuf);
npage = BufferGetPage(nbuf);
nopaque = (HashPageOpaque) PageGetSpecialPointer(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
* the current page in the new bucket, we must allocate a new
* overflow page and place the tuple on that page instead.
*/
- itemsz = IndexTupleDSize(*new_itup);
+ itemsz = IndexTupleSize(new_itup);
itemsz = MAXALIGN(itemsz);
- if (PageGetFreeSpace(npage) < itemsz)
+ if (PageGetFreeSpaceForMultipleTuples(npage, nitups + 1) < (all_tups_size + itemsz))
{
- /* write out nbuf and drop lock, but keep pin */
- _hash_chgbufaccess(rel, nbuf, HASH_WRITE, HASH_NOLOCK);
+ /*
+ * 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) ? true : false);
npage = BufferGetPage(nbuf);
nopaque = (HashPageOpaque) PageGetSpecialPointer(npage);
}
- /*
- * Insert tuple on new page, using _hash_pgaddtup to ensure
- * correct ordering by hashkey. This is a tad inefficient
- * since we may have to shuffle itempointers repeatedly.
- * Possible future improvement: accumulate all the items for
- * the new page and qsort them before insertion.
- */
- (void) _hash_pgaddtup(rel, nbuf, itemsz, new_itup);
-
- /* be tidy */
- pfree(new_itup);
+ itups[nitups++] = new_itup;
+ all_tups_size += itemsz;
}
else
{
/* retain the pin on the old primary bucket */
if (obuf == bucket_obuf)
- _hash_chgbufaccess(rel, obuf, HASH_READ, HASH_NOLOCK);
+ 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);
* To avoid deadlocks due to locking order of buckets, first lock the old
* bucket and then the new bucket.
*/
- if (nbuf == bucket_nbuf)
- _hash_chgbufaccess(rel, bucket_nbuf, HASH_WRITE, HASH_NOLOCK);
- else
- _hash_wrtbuf(rel, nbuf);
-
- _hash_chgbufaccess(rel, bucket_obuf, HASH_NOLOCK, HASH_WRITE);
+ LockBuffer(bucket_obuf, BUFFER_LOCK_EXCLUSIVE);
opage = BufferGetPage(bucket_obuf);
oopaque = (HashPageOpaque) PageGetSpecialPointer(opage);
- _hash_chgbufaccess(rel, bucket_nbuf, HASH_NOLOCK, HASH_WRITE);
+ LockBuffer(bucket_nbuf, BUFFER_LOCK_EXCLUSIVE);
npage = BufferGetPage(bucket_nbuf);
nopaque = (HashPageOpaque) PageGetSpecialPointer(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. Vacuum will clear split-cleanup flag after
- * deleting such tuples.
+ * 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;
*/
MarkBufferDirty(bucket_obuf);
MarkBufferDirty(bucket_nbuf);
+
+ if (RelationNeedsWAL(rel))
+ {
+ XLogRecPtr recptr;
+ xl_hash_split_complete xlrec;
+
+ xlrec.old_bucket_flag = oopaque->hasho_flag;
+ xlrec.new_bucket_flag = nopaque->hasho_flag;
+
+ XLogBeginInsert();
+
+ XLogRegisterData((char *) &xlrec, SizeOfHashSplitComplete);
+
+ XLogRegisterBuffer(0, bucket_obuf, REGBUF_STANDARD);
+ XLogRegisterBuffer(1, bucket_nbuf, REGBUF_STANDARD);
+
+ recptr = XLogInsert(RM_HASH_ID, XLOG_HASH_SPLIT_COMPLETE);
+
+ 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);
+ }
}
/*
* already moved before the split operation was previously interrupted.
*
* The caller must hold a pin, but no lock, on the metapage and old bucket's
- * primay page buffer. The buffers are returned in the same state. (The
+ * primary page buffer. The buffers are returned in the same state. (The
* metapage is only touched if it becomes necessary to add or remove overflow
* pages.)
*/
* retain the pin on primary bucket.
*/
if (nbuf == bucket_nbuf)
- _hash_chgbufaccess(rel, nbuf, HASH_READ, HASH_NOLOCK);
+ LockBuffer(nbuf, BUFFER_LOCK_UNLOCK);
else
_hash_relbuf(rel, nbuf);
}
if (!ConditionalLockBufferForCleanup(bucket_nbuf))
{
- _hash_chgbufaccess(rel, obuf, HASH_READ, HASH_NOLOCK);
+ LockBuffer(obuf, BUFFER_LOCK_UNLOCK);
hash_destroy(tidhtab);
return;
}
npageopaque = (HashPageOpaque) PageGetSpecialPointer(npage);
nbucket = npageopaque->hasho_bucket;
- _hash_splitbucket_guts(rel, metabuf, obucket,
- nbucket, obuf, bucket_nbuf, tidhtab,
- maxbucket, highmask, lowmask);
+ _hash_splitbucket(rel, metabuf, obucket,
+ nbucket, obuf, bucket_nbuf, tidhtab,
+ maxbucket, highmask, lowmask);
- _hash_relbuf(rel, bucket_nbuf);
- _hash_chgbufaccess(rel, obuf, HASH_READ, HASH_NOLOCK);
+ _hash_dropbuf(rel, bucket_nbuf);
hash_destroy(tidhtab);
}
+
+/*
+ * log_split_page() -- Log the split operation
+ *
+ * We log the split operation when the new page in new bucket gets full,
+ * so we log the entire page.
+ *
+ * 'buf' must be locked by the caller which is also responsible for unlocking
+ * it.
+ */
+static void
+log_split_page(Relation rel, Buffer buf)
+{
+ 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);
+ }
+}
+
+/*
+ * _hash_getcachedmetap() -- Returns cached metapage data.
+ *
+ * If metabuf is not InvalidBuffer, caller must hold a pin, but no lock, on
+ * the metapage. If not set, we'll set it before returning if we have to
+ * refresh the cache, and return with a pin but no lock on it; caller is
+ * responsible for releasing the pin.
+ *
+ * We refresh the cache if it's not initialized yet or force_refresh is true.
+ */
+HashMetaPage
+_hash_getcachedmetap(Relation rel, Buffer *metabuf, bool force_refresh)
+{
+ 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 succeeeded.
+ */
+ 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;
+}
+
+/*
+ * _hash_getbucketbuf_from_hashkey() -- Get the bucket's buffer for the given
+ * hashkey.
+ *
+ * Bucket pages do not move or get removed once they are allocated. This give
+ * us an opportunity to use the previously saved metapage contents to reach
+ * the target bucket buffer, instead of reading from the metapage every time.
+ * This saves one buffer access every time we want to reach the target bucket
+ * buffer, which is very helpful savings in bufmgr traffic and contention.
+ *
+ * The access type parameter (HASH_READ or HASH_WRITE) indicates whether the
+ * bucket buffer has to be locked for reading or writing.
+ *
+ * The out parameter cachedmetap is set with metapage contents used for
+ * hashkey to bucket buffer mapping. Some callers need this info to reach the
+ * old bucket in case of bucket split, see _hash_doinsert().
+ */
+Buffer
+_hash_getbucketbuf_from_hashkey(Relation rel, uint32 hashkey, int access,
+ HashMetaPage *cachedmetap)
+{
+ 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 = (HashPageOpaque) PageGetSpecialPointer(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;
+}
projects / postgresql / blobdiff