hash: Refactor hash index creation.
The primary goal here is to move all of the related page modifications to a single section of code, in preparation for adding write-ahead logging. In passing, rename _hash_metapinit to _hash_init, since it initializes more than just the metapage. Amit Kapila. The larger patch series of which this is a part has been reviewed and tested by Álvaro Herrera, Ashutosh Sharma, Mark Kirkwood, Jeff Janes, and Jesper Pedersen.
This commit is contained in:
Robert Haas
parent
2b87dd8d7a
commit
38305398cd
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@ -120,7 +120,7 @@ hashbuild(Relation heap, Relation index, IndexInfo *indexInfo)
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estimate_rel_size(heap, NULL, &relpages, &reltuples, &allvisfrac);
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/* Initialize the hash index metadata page and initial buckets */
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num_buckets = _hash_metapinit(index, reltuples, MAIN_FORKNUM);
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num_buckets = _hash_init(index, reltuples, MAIN_FORKNUM);
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/*
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* If we just insert the tuples into the index in scan order, then
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@ -182,7 +182,7 @@ hashbuild(Relation heap, Relation index, IndexInfo *indexInfo)
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void
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hashbuildempty(Relation index)
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{
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_hash_metapinit(index, 0, INIT_FORKNUM);
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_hash_init(index, 0, INIT_FORKNUM);
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}
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/*
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@ -570,68 +570,6 @@ _hash_freeovflpage(Relation rel, Buffer bucketbuf, Buffer ovflbuf,
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}
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/*
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* _hash_initbitmap()
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*
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* Initialize a new bitmap page. The metapage has a write-lock upon
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* entering the function, and must be written by caller after return.
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*
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* 'blkno' is the block number of the new bitmap page.
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*
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* All bits in the new bitmap page are set to "1", indicating "in use".
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*/
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void
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_hash_initbitmap(Relation rel, HashMetaPage metap, BlockNumber blkno,
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ForkNumber forkNum)
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{
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Buffer buf;
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Page pg;
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HashPageOpaque op;
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uint32 *freep;
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/*
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* It is okay to write-lock the new bitmap page while holding metapage
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* write lock, because no one else could be contending for the new page.
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* Also, the metapage lock makes it safe to extend the index using
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* _hash_getnewbuf.
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*
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* There is some loss of concurrency in possibly doing I/O for the new
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* page while holding the metapage lock, but this path is taken so seldom
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* that it's not worth worrying about.
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*/
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buf = _hash_getnewbuf(rel, blkno, forkNum);
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pg = BufferGetPage(buf);
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/* initialize the page's special space */
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op = (HashPageOpaque) PageGetSpecialPointer(pg);
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op->hasho_prevblkno = InvalidBlockNumber;
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op->hasho_nextblkno = InvalidBlockNumber;
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op->hasho_bucket = -1;
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op->hasho_flag = LH_BITMAP_PAGE;
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op->hasho_page_id = HASHO_PAGE_ID;
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/* set all of the bits to 1 */
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freep = HashPageGetBitmap(pg);
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MemSet(freep, 0xFF, BMPGSZ_BYTE(metap));
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/* dirty the new bitmap page, and release write lock and pin */
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MarkBufferDirty(buf);
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_hash_relbuf(rel, buf);
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/* add the new bitmap page to the metapage's list of bitmaps */
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/* metapage already has a write lock */
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if (metap->hashm_nmaps >= HASH_MAX_BITMAPS)
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ereport(ERROR,
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(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
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errmsg("out of overflow pages in hash index \"%s\"",
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RelationGetRelationName(rel))));
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metap->hashm_mapp[metap->hashm_nmaps] = blkno;
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metap->hashm_nmaps++;
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}
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/*
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* _hash_initbitmapbuffer()
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*
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@ -156,6 +156,36 @@ _hash_getinitbuf(Relation rel, BlockNumber blkno)
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return buf;
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}
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/*
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* _hash_initbuf() -- Get and initialize a buffer by bucket number.
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*/
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void
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_hash_initbuf(Buffer buf, uint32 max_bucket, uint32 num_bucket, uint32 flag,
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bool initpage)
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{
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HashPageOpaque pageopaque;
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Page page;
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page = BufferGetPage(buf);
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/* initialize the page */
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if (initpage)
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_hash_pageinit(page, BufferGetPageSize(buf));
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pageopaque = (HashPageOpaque) PageGetSpecialPointer(page);
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/*
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* Set hasho_prevblkno with current hashm_maxbucket. This value will
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* be used to validate cached HashMetaPageData. See
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* _hash_getbucketbuf_from_hashkey().
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*/
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pageopaque->hasho_prevblkno = max_bucket;
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pageopaque->hasho_nextblkno = InvalidBlockNumber;
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pageopaque->hasho_bucket = num_bucket;
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pageopaque->hasho_flag = flag;
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pageopaque->hasho_page_id = HASHO_PAGE_ID;
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}
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/*
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* _hash_getnewbuf() -- Get a new page at the end of the index.
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*
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@ -288,7 +318,7 @@ _hash_dropscanbuf(Relation rel, HashScanOpaque so)
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/*
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* _hash_metapinit() -- Initialize the metadata page of a hash index,
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* _hash_init() -- Initialize the metadata page of a hash index,
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* the initial buckets, and the initial bitmap page.
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*
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* The initial number of buckets is dependent on num_tuples, an estimate
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@ -300,19 +330,18 @@ _hash_dropscanbuf(Relation rel, HashScanOpaque so)
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* multiple buffer locks is ignored.
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*/
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uint32
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_hash_metapinit(Relation rel, double num_tuples, ForkNumber forkNum)
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_hash_init(Relation rel, double num_tuples, ForkNumber forkNum)
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{
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HashMetaPage metap;
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HashPageOpaque pageopaque;
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Buffer metabuf;
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Buffer buf;
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Buffer bitmapbuf;
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Page pg;
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HashMetaPage metap;
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RegProcedure procid;
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int32 data_width;
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int32 item_width;
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int32 ffactor;
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double dnumbuckets;
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uint32 num_buckets;
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uint32 log2_num_buckets;
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uint32 i;
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/* safety check */
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@ -334,6 +363,96 @@ _hash_metapinit(Relation rel, double num_tuples, ForkNumber forkNum)
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if (ffactor < 10)
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ffactor = 10;
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procid = index_getprocid(rel, 1, HASHPROC);
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/*
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* We initialize the metapage, the first N bucket pages, and the first
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* bitmap page in sequence, using _hash_getnewbuf to cause smgrextend()
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* calls to occur. This ensures that the smgr level has the right idea of
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* the physical index length.
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*
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* Critical section not required, because on error the creation of the
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* whole relation will be rolled back.
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*/
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metabuf = _hash_getnewbuf(rel, HASH_METAPAGE, forkNum);
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_hash_init_metabuffer(metabuf, num_tuples, procid, ffactor, false);
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MarkBufferDirty(metabuf);
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pg = BufferGetPage(metabuf);
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metap = HashPageGetMeta(pg);
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num_buckets = metap->hashm_maxbucket + 1;
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/*
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* Release buffer lock on the metapage while we initialize buckets.
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* Otherwise, we'll be in interrupt holdoff and the CHECK_FOR_INTERRUPTS
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* won't accomplish anything. It's a bad idea to hold buffer locks for
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* long intervals in any case, since that can block the bgwriter.
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*/
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LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
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/*
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* Initialize and WAL Log the first N buckets
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*/
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for (i = 0; i < num_buckets; i++)
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{
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BlockNumber blkno;
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/* Allow interrupts, in case N is huge */
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CHECK_FOR_INTERRUPTS();
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blkno = BUCKET_TO_BLKNO(metap, i);
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buf = _hash_getnewbuf(rel, blkno, forkNum);
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_hash_initbuf(buf, metap->hashm_maxbucket, i, LH_BUCKET_PAGE, false);
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MarkBufferDirty(buf);
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_hash_relbuf(rel, buf);
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}
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/* Now reacquire buffer lock on metapage */
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LockBuffer(metabuf, BUFFER_LOCK_EXCLUSIVE);
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/*
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* Initialize bitmap page
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*/
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bitmapbuf = _hash_getnewbuf(rel, num_buckets + 1, forkNum);
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_hash_initbitmapbuffer(bitmapbuf, metap->hashm_bmsize, false);
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MarkBufferDirty(bitmapbuf);
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/* add the new bitmap page to the metapage's list of bitmaps */
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/* metapage already has a write lock */
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if (metap->hashm_nmaps >= HASH_MAX_BITMAPS)
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ereport(ERROR,
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(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
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errmsg("out of overflow pages in hash index \"%s\"",
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RelationGetRelationName(rel))));
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metap->hashm_mapp[metap->hashm_nmaps] = num_buckets + 1;
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metap->hashm_nmaps++;
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MarkBufferDirty(metabuf);
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/* all done */
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_hash_relbuf(rel, bitmapbuf);
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_hash_relbuf(rel, metabuf);
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return num_buckets;
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}
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/*
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* _hash_init_metabuffer() -- Initialize the metadata page of a hash index.
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*/
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void
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_hash_init_metabuffer(Buffer buf, double num_tuples, RegProcedure procid,
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uint16 ffactor, bool initpage)
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{
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HashMetaPage metap;
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HashPageOpaque pageopaque;
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Page page;
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double dnumbuckets;
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uint32 num_buckets;
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uint32 log2_num_buckets;
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uint32 i;
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/*
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* Choose the number of initial bucket pages to match the fill factor
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* given the estimated number of tuples. We round up the result to the
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@ -353,30 +472,25 @@ _hash_metapinit(Relation rel, double num_tuples, ForkNumber forkNum)
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Assert(num_buckets == (((uint32) 1) << log2_num_buckets));
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Assert(log2_num_buckets < HASH_MAX_SPLITPOINTS);
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/*
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* We initialize the metapage, the first N bucket pages, and the first
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* bitmap page in sequence, using _hash_getnewbuf to cause smgrextend()
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* calls to occur. This ensures that the smgr level has the right idea of
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* the physical index length.
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*/
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metabuf = _hash_getnewbuf(rel, HASH_METAPAGE, forkNum);
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pg = BufferGetPage(metabuf);
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page = BufferGetPage(buf);
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if (initpage)
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_hash_pageinit(page, BufferGetPageSize(buf));
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pageopaque = (HashPageOpaque) PageGetSpecialPointer(pg);
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pageopaque = (HashPageOpaque) PageGetSpecialPointer(page);
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pageopaque->hasho_prevblkno = InvalidBlockNumber;
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pageopaque->hasho_nextblkno = InvalidBlockNumber;
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pageopaque->hasho_bucket = -1;
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pageopaque->hasho_flag = LH_META_PAGE;
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pageopaque->hasho_page_id = HASHO_PAGE_ID;
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metap = HashPageGetMeta(pg);
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metap = HashPageGetMeta(page);
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metap->hashm_magic = HASH_MAGIC;
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metap->hashm_version = HASH_VERSION;
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metap->hashm_ntuples = 0;
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metap->hashm_nmaps = 0;
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metap->hashm_ffactor = ffactor;
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metap->hashm_bsize = HashGetMaxBitmapSize(pg);
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metap->hashm_bsize = HashGetMaxBitmapSize(page);
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/* find largest bitmap array size that will fit in page size */
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for (i = _hash_log2(metap->hashm_bsize); i > 0; --i)
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{
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@ -393,7 +507,7 @@ _hash_metapinit(Relation rel, double num_tuples, ForkNumber forkNum)
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* pretty useless for normal operation (in fact, hashm_procid is not used
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* anywhere), but it might be handy for forensic purposes so we keep it.
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*/
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metap->hashm_procid = index_getprocid(rel, 1, HASHPROC);
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metap->hashm_procid = procid;
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/*
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* We initialize the index with N buckets, 0 .. N-1, occupying physical
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@ -411,54 +525,9 @@ _hash_metapinit(Relation rel, double num_tuples, ForkNumber forkNum)
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metap->hashm_ovflpoint = log2_num_buckets;
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metap->hashm_firstfree = 0;
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/*
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* Release buffer lock on the metapage while we initialize buckets.
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* Otherwise, we'll be in interrupt holdoff and the CHECK_FOR_INTERRUPTS
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* won't accomplish anything. It's a bad idea to hold buffer locks for
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* long intervals in any case, since that can block the bgwriter.
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*/
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MarkBufferDirty(metabuf);
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LockBuffer(metabuf, BUFFER_LOCK_UNLOCK);
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/*
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* Initialize the first N buckets
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*/
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for (i = 0; i < num_buckets; i++)
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{
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/* Allow interrupts, in case N is huge */
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CHECK_FOR_INTERRUPTS();
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buf = _hash_getnewbuf(rel, BUCKET_TO_BLKNO(metap, i), forkNum);
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pg = BufferGetPage(buf);
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pageopaque = (HashPageOpaque) PageGetSpecialPointer(pg);
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/*
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* Set hasho_prevblkno with current hashm_maxbucket. This value will
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* be used to validate cached HashMetaPageData. See
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* _hash_getbucketbuf_from_hashkey().
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*/
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pageopaque->hasho_prevblkno = metap->hashm_maxbucket;
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pageopaque->hasho_nextblkno = InvalidBlockNumber;
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pageopaque->hasho_bucket = i;
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pageopaque->hasho_flag = LH_BUCKET_PAGE;
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pageopaque->hasho_page_id = HASHO_PAGE_ID;
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MarkBufferDirty(buf);
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_hash_relbuf(rel, buf);
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}
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/* Now reacquire buffer lock on metapage */
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LockBuffer(metabuf, BUFFER_LOCK_EXCLUSIVE);
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/*
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* Initialize first bitmap page
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*/
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_hash_initbitmap(rel, metap, num_buckets + 1, forkNum);
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/* all done */
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MarkBufferDirty(metabuf);
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_hash_relbuf(rel, metabuf);
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return num_buckets;
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/* Set pd_lower just past the end of the metadata. */
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((PageHeader) page)->pd_lower =
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((char *) metap + sizeof(HashMetaPageData)) - (char *) page;
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}
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/*
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@ -535,7 +604,7 @@ restart_expand:
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* than a disk block then this would be an independent constraint.
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*
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* If you change this, see also the maximum initial number of buckets in
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* _hash_metapinit().
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* _hash_init().
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*/
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if (metap->hashm_maxbucket >= (uint32) 0x7FFFFFFE)
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goto fail;
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@ -311,8 +311,6 @@ extern Buffer _hash_addovflpage(Relation rel, Buffer metabuf, Buffer buf, bool r
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extern BlockNumber _hash_freeovflpage(Relation rel, Buffer bucketbuf, Buffer ovflbuf,
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Buffer wbuf, IndexTuple *itups, OffsetNumber *itup_offsets,
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Size *tups_size, uint16 nitups, BufferAccessStrategy bstrategy);
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extern void _hash_initbitmap(Relation rel, HashMetaPage metap,
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BlockNumber blkno, ForkNumber forkNum);
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extern void _hash_initbitmapbuffer(Buffer buf, uint16 bmsize, bool initpage);
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extern void _hash_squeezebucket(Relation rel,
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Bucket bucket, BlockNumber bucket_blkno,
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@ -331,6 +329,8 @@ extern Buffer _hash_getbucketbuf_from_hashkey(Relation rel, uint32 hashkey,
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int access,
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HashMetaPage *cachedmetap);
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extern Buffer _hash_getinitbuf(Relation rel, BlockNumber blkno);
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extern void _hash_initbuf(Buffer buf, uint32 max_bucket, uint32 num_bucket,
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uint32 flag, bool initpage);
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extern Buffer _hash_getnewbuf(Relation rel, BlockNumber blkno,
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ForkNumber forkNum);
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extern Buffer _hash_getbuf_with_strategy(Relation rel, BlockNumber blkno,
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@ -339,8 +339,10 @@ extern Buffer _hash_getbuf_with_strategy(Relation rel, BlockNumber blkno,
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extern void _hash_relbuf(Relation rel, Buffer buf);
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extern void _hash_dropbuf(Relation rel, Buffer buf);
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extern void _hash_dropscanbuf(Relation rel, HashScanOpaque so);
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extern uint32 _hash_metapinit(Relation rel, double num_tuples,
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ForkNumber forkNum);
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extern uint32 _hash_init(Relation rel, double num_tuples,
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ForkNumber forkNum);
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extern void _hash_init_metabuffer(Buffer buf, double num_tuples,
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RegProcedure procid, uint16 ffactor, bool initpage);
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extern void _hash_pageinit(Page page, Size size);
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extern void _hash_expandtable(Relation rel, Buffer metabuf);
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extern void _hash_finish_split(Relation rel, Buffer metabuf, Buffer obuf,
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