gist.c

关系型数据库 Postgresql 6.5.2

	InsertIndexResult res;
	GISTENTRY	tmpentry;
	IndexTuple	newtup;

	b = ReadBuffer(r, stk->gs_blk);
	p = BufferGetPage(b);

	if (gistnospace(p, ltup))
	{
		res = gistSplit(r, b, stk->gs_parent, ltup, giststate);
		WriteBuffer(b);			/* don't forget to release buffer!  -
								 * 01/31/94 */
		pfree(res);
		gistdoinsert(r, rtup, giststate);
	}
	else
	{
		gistPageAddItem(giststate, r, p, (Item) ltup,
						IndexTupleSize(ltup), InvalidOffsetNumber,
						LP_USED, &tmpentry, &newtup);
		WriteBuffer(b);
		gistAdjustKeys(r, stk->gs_parent, stk->gs_blk, tmpentry.pred,
					   tmpentry.bytes, giststate);
		/* be tidy */
		if (tmpentry.pred != (((char *) ltup) + sizeof(IndexTupleData)))
			pfree(tmpentry.pred);
		if (ltup != newtup)
			pfree(newtup);
		gistentryinsert(r, stk, rtup, giststate);
	}
}


/*
** Insert an entry onto a page
*/
static InsertIndexResult
gistentryinsert(Relation r, GISTSTACK *stk, IndexTuple tup,
				GISTSTATE *giststate)
{
	Buffer		b;
	Page		p;
	InsertIndexResult res;
	OffsetNumber off;
	GISTENTRY	tmpentry;
	IndexTuple	newtup;

	b = ReadBuffer(r, stk->gs_blk);
	p = BufferGetPage(b);

	if (gistnospace(p, tup))
	{
		res = gistSplit(r, b, stk->gs_parent, tup, giststate);
		WriteBuffer(b);			/* don't forget to release buffer!  -
								 * 01/31/94 */
		return res;
	}
	else
	{
		res = (InsertIndexResult) palloc(sizeof(InsertIndexResultData));
		off = gistPageAddItem(giststate, r, p, (Item) tup, IndexTupleSize(tup),
					   InvalidOffsetNumber, LP_USED, &tmpentry, &newtup);
		WriteBuffer(b);
		ItemPointerSet(&(res->pointerData), stk->gs_blk, off);
		gistAdjustKeys(r, stk->gs_parent, stk->gs_blk, tmpentry.pred,
					   tmpentry.bytes, giststate);
		/* be tidy */
		if (tmpentry.pred != (((char *) tup) + sizeof(IndexTupleData)))
			pfree(tmpentry.pred);
		if (tup != newtup)
			pfree(newtup);
		return res;
	}
}


static void
gistnewroot(GISTSTATE *giststate, Relation r, IndexTuple lt, IndexTuple rt)
{
	Buffer		b;
	Page		p;
	GISTENTRY	tmpentry;
	IndexTuple	newtup;

	b = ReadBuffer(r, GISTP_ROOT);
	GISTInitBuffer(b, 0);
	p = BufferGetPage(b);
	gistPageAddItem(giststate, r, p, (Item) lt, IndexTupleSize(lt),
					FirstOffsetNumber,
					LP_USED, &tmpentry, &newtup);
	/* be tidy */
	if (tmpentry.pred != (((char *) lt) + sizeof(IndexTupleData)))
		pfree(tmpentry.pred);
	if (lt != newtup)
		pfree(newtup);
	gistPageAddItem(giststate, r, p, (Item) rt, IndexTupleSize(rt),
					OffsetNumberNext(FirstOffsetNumber), LP_USED,
					&tmpentry, &newtup);
	/* be tidy */
	if (tmpentry.pred != (((char *) rt) + sizeof(IndexTupleData)))
		pfree(tmpentry.pred);
	if (rt != newtup)
		pfree(newtup);
	WriteBuffer(b);
}

static void
GISTInitBuffer(Buffer b, uint32 f)
{
	GISTPageOpaque opaque;
	Page		page;
	Size		pageSize;

	pageSize = BufferGetPageSize(b);

	page = BufferGetPage(b);
	MemSet(page, 0, (int) pageSize);
	PageInit(page, pageSize, sizeof(GISTPageOpaqueData));

	opaque = (GISTPageOpaque) PageGetSpecialPointer(page);
	opaque->flags = f;
}


/*
** find entry with lowest penalty
*/
static OffsetNumber
gistchoose(Relation r, Page p, IndexTuple it,	/* it has compressed entry */
		   GISTSTATE *giststate)
{
	OffsetNumber maxoff;
	OffsetNumber i;
	char	   *id;
	char	   *datum;
	float		usize;
	OffsetNumber which;
	float		which_grow;
	GISTENTRY	entry,
				identry;
	int			size,
				idsize;

	idsize = IndexTupleSize(it) - sizeof(IndexTupleData);
	id = ((char *) it) + sizeof(IndexTupleData);
	maxoff = PageGetMaxOffsetNumber(p);
	which_grow = -1.0;
	which = -1;

	gistdentryinit(giststate, &identry, id, (Relation) NULL, (Page) NULL,
				   (OffsetNumber) 0, idsize, FALSE);

	for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
	{
		datum = (char *) PageGetItem(p, PageGetItemId(p, i));
		size = IndexTupleSize(datum) - sizeof(IndexTupleData);
		datum += sizeof(IndexTupleData);
		gistdentryinit(giststate, &entry, datum, r, p, i, size, FALSE);
		(*fmgr_faddr(&giststate->penaltyFn)) (&entry, &identry, &usize);
		if (which_grow < 0 || usize < which_grow)
		{
			which = i;
			which_grow = usize;
			if (which_grow == 0)
				break;
		}
		if (entry.pred != datum)
			pfree(entry.pred);
	}
	if (identry.pred != id)
		pfree(identry.pred);

	return which;
}

static int
gistnospace(Page p, IndexTuple it)
{
	return PageGetFreeSpace(p) < IndexTupleSize(it);
}

void
gistfreestack(GISTSTACK *s)
{
	GISTSTACK  *p;

	while (s != (GISTSTACK *) NULL)
	{
		p = s->gs_parent;
		pfree(s);
		s = p;
	}
}


/*
** remove an entry from a page
*/
void
gistdelete(Relation r, ItemPointer tid)
{
	BlockNumber blkno;
	OffsetNumber offnum;
	Buffer		buf;
	Page		page;

	/*
	 * Notes in ExecUtils:ExecOpenIndices() Also note that only vacuum
	 * deletes index tuples now...
	 *
	 * RelationSetLockForWrite(r);
	 */

	blkno = ItemPointerGetBlockNumber(tid);
	offnum = ItemPointerGetOffsetNumber(tid);

	/* adjust any scans that will be affected by this deletion */
	gistadjscans(r, GISTOP_DEL, blkno, offnum);

	/* delete the index tuple */
	buf = ReadBuffer(r, blkno);
	page = BufferGetPage(buf);

	PageIndexTupleDelete(page, offnum);

	WriteBuffer(buf);

}

void
initGISTstate(GISTSTATE *giststate, Relation index)
{
	RegProcedure consistent_proc,
				union_proc,
				compress_proc,
				decompress_proc;
	RegProcedure penalty_proc,
				picksplit_proc,
				equal_proc;
	HeapTuple	htup;
	Form_pg_index itupform;

	consistent_proc = index_getprocid(index, 1, GIST_CONSISTENT_PROC);
	union_proc = index_getprocid(index, 1, GIST_UNION_PROC);
	compress_proc = index_getprocid(index, 1, GIST_COMPRESS_PROC);
	decompress_proc = index_getprocid(index, 1, GIST_DECOMPRESS_PROC);
	penalty_proc = index_getprocid(index, 1, GIST_PENALTY_PROC);
	picksplit_proc = index_getprocid(index, 1, GIST_PICKSPLIT_PROC);
	equal_proc = index_getprocid(index, 1, GIST_EQUAL_PROC);
	fmgr_info(consistent_proc, &giststate->consistentFn);
	fmgr_info(union_proc, &giststate->unionFn);
	fmgr_info(compress_proc, &giststate->compressFn);
	fmgr_info(decompress_proc, &giststate->decompressFn);
	fmgr_info(penalty_proc, &giststate->penaltyFn);
	fmgr_info(picksplit_proc, &giststate->picksplitFn);
	fmgr_info(equal_proc, &giststate->equalFn);

	/* see if key type is different from type of attribute being indexed */
	htup = SearchSysCacheTuple(INDEXRELID,
							   ObjectIdGetDatum(RelationGetRelid(index)),
							   0, 0, 0);
	itupform = (Form_pg_index) GETSTRUCT(htup);
	if (!HeapTupleIsValid(htup))
		elog(ERROR, "initGISTstate: index %u not found",
			 RelationGetRelid(index));
	giststate->haskeytype = itupform->indhaskeytype;
	if (giststate->haskeytype)
	{
		/* key type is different -- is it byval? */
		htup = SearchSysCacheTuple(ATTNUM,
								   ObjectIdGetDatum(itupform->indexrelid),
								   UInt16GetDatum(FirstOffsetNumber),
								   0, 0);
		if (!HeapTupleIsValid(htup))
		{
			elog(ERROR, "initGISTstate: no attribute tuple %u %d",
				 itupform->indexrelid, FirstOffsetNumber);
			return;
		}
		giststate->keytypbyval = (((Form_pg_attribute) htup)->attbyval);
	}
	else
		giststate->keytypbyval = FALSE;
	return;
}


/*
** Given an IndexTuple to be inserted on a page, this routine replaces
** the key with another key, which may involve generating a new IndexTuple
** if the sizes don't match
*/
static IndexTuple
gist_tuple_replacekey(Relation r, GISTENTRY entry, IndexTuple t)
{
	char	   *datum = (((char *) t) + sizeof(IndexTupleData));

	/* if new entry fits in index tuple, copy it in */
	if (entry.bytes < IndexTupleSize(t) - sizeof(IndexTupleData))
	{
		memcpy(datum, entry.pred, entry.bytes);
		/* clear out old size */
		t->t_info &= 0xe000;
		/* or in new size */
		t->t_info |= MAXALIGN(entry.bytes + sizeof(IndexTupleData));

		return t;
	}
	else
	{
		/* generate a new index tuple for the compressed entry */
		TupleDesc	tupDesc = r->rd_att;
		IndexTuple	newtup;
		char	   *isnull;
		int			blank;

		isnull = (char *) palloc(r->rd_rel->relnatts);
		for (blank = 0; blank < r->rd_rel->relnatts; blank++)
			isnull[blank] = ' ';
		newtup = (IndexTuple) index_formtuple(tupDesc,
											  (Datum *) &(entry.pred),
											  isnull);
		newtup->t_tid = t->t_tid;
		pfree(isnull);
		return newtup;
	}
}


/*
** initialize a GiST entry with a decompressed version of pred
*/
void
gistdentryinit(GISTSTATE *giststate, GISTENTRY *e, char *pr, Relation r,
			   Page pg, OffsetNumber o, int b, bool l)
{
	GISTENTRY  *dep;

	gistentryinit(*e, pr, r, pg, o, b, l);
	if (giststate->haskeytype)
	{
		dep = (GISTENTRY *) ((*fmgr_faddr(&giststate->decompressFn)) (e));
		gistentryinit(*e, dep->pred, dep->rel, dep->page, dep->offset, dep->bytes,
					  dep->leafkey);
		if (dep != e)
			pfree(dep);
	}
}


/*
** initialize a GiST entry with a compressed version of pred
*/
static void
gistcentryinit(GISTSTATE *giststate, GISTENTRY *e, char *pr, Relation r,
			   Page pg, OffsetNumber o, int b, bool l)
{
	GISTENTRY  *cep;

	gistentryinit(*e, pr, r, pg, o, b, l);
	if (giststate->haskeytype)
	{
		cep = (GISTENTRY *) ((*fmgr_faddr(&giststate->compressFn)) (e));
		gistentryinit(*e, cep->pred, cep->rel, cep->page, cep->offset, cep->bytes,
					  cep->leafkey);
		if (cep != e)
			pfree(cep);
	}
}



#ifdef GISTDEBUG

/*
** sloppy debugging support routine, requires recompilation with appropriate
** "out" method for the index keys.  Could be fixed to find that info
** in the catalogs...
*/
void
_gistdump(Relation r)
{
	Buffer		buf;
	Page		page;
	OffsetNumber offnum,
				maxoff;
	BlockNumber blkno;
	BlockNumber nblocks;
	GISTPageOpaque po;
	IndexTuple	itup;
	BlockNumber itblkno;
	OffsetNumber itoffno;
	char	   *datum;
	char	   *itkey;

	nblocks = RelationGetNumberOfBlocks(r);
	for (blkno = 0; blkno < nblocks; blkno++)
	{
		buf = ReadBuffer(r, blkno);
		page = BufferGetPage(buf);
		po = (GISTPageOpaque) PageGetSpecialPointer(page);
		maxoff = PageGetMaxOffsetNumber(page);
		printf("Page %d maxoff %d <%s>\n", blkno, maxoff,
			   (po->flags & F_LEAF ? "LEAF" : "INTERNAL"));

		if (PageIsEmpty(page))
		{
			ReleaseBuffer(buf);
			continue;
		}

		for (offnum = FirstOffsetNumber;
			 offnum <= maxoff;
			 offnum = OffsetNumberNext(offnum))
		{
			itup = (IndexTuple) PageGetItem(page, PageGetItemId(page, offnum));
			itblkno = ItemPointerGetBlockNumber(&(itup->t_tid));
			itoffno = ItemPointerGetOffsetNumber(&(itup->t_tid));
			datum = ((char *) itup);
			datum += sizeof(IndexTupleData);
			/* get out function for type of key, and out it! */
			itkey = (char *) int_range_out((INTRANGE *) datum);
			/* itkey = " unable to print"; */
			printf("\t[%d] size %d heap <%d,%d> key:%s\n",
				   offnum, IndexTupleSize(itup), itblkno, itoffno, itkey);
			pfree(itkey);
		}

		ReleaseBuffer(buf);
	}
}

static char *
int_range_out(INTRANGE *r)
{
	char	   *result;

	if (r == NULL)
		return NULL;
	result = (char *) palloc(80);
	snprintf(result, 80, "[%d,%d): %d", r->lower, r->upper, r->flag);

	return result;
}

#endif	 /* defined GISTDEBUG */