gist.c

PostgreSQL7.4.6 for Linux

	GISTENTRY	entry,
				identry[INDEX_MAX_KEYS];
	bool		IsNull,
				decompvec[INDEX_MAX_KEYS],
				isnull[INDEX_MAX_KEYS];
	int			j;

	maxoff = PageGetMaxOffsetNumber(p);
	*which_grow = -1.0;
	which = -1;
	sum_grow = 1;
	gistDeCompressAtt(giststate, r,
					  it, (Page) NULL, (OffsetNumber) 0,
					  identry, decompvec, isnull);

	for (i = FirstOffsetNumber; i <= maxoff && sum_grow; i = OffsetNumberNext(i))
	{
		IndexTuple	itup = (IndexTuple) PageGetItem(p, PageGetItemId(p, i));

		sum_grow = 0;
		for (j = 0; j < r->rd_att->natts; j++)
		{
			datum = index_getattr(itup, j + 1, giststate->tupdesc, &IsNull);
			gistdentryinit(giststate, j, &entry, datum, r, p, i, ATTSIZE(datum, giststate->tupdesc, j + 1, IsNull), FALSE, IsNull);
			gistpenalty(giststate, j, &entry, IsNull, &identry[j], isnull[j], &usize);

			if ((!isAttByVal(giststate, j)) && entry.key != datum)
				pfree(DatumGetPointer(entry.key));

			if (which_grow[j] < 0 || usize < which_grow[j])
			{
				which = i;
				which_grow[j] = usize;
				if (j < r->rd_att->natts - 1 && i == FirstOffsetNumber)
					which_grow[j + 1] = -1;
				sum_grow += which_grow[j];
			}
			else if (which_grow[j] == usize)
				sum_grow += usize;
			else
			{
				sum_grow = 1;
				break;
			}
		}
	}

	gistFreeAtt(r, identry, decompvec);
	return which;
}

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

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


/*
 * Retail deletion of a single tuple.
 *
 * NB: this is no longer called externally, but is still needed by
 * gistlayerinsert().  That dependency will have to be fixed if GIST
 * is ever going to allow concurrent insertions.
 */
static void
gistdelete(Relation r, ItemPointer tid)
{
	BlockNumber blkno;
	OffsetNumber offnum;
	Buffer		buf;
	Page		page;

	/*
	 * Since GIST is not marked "amconcurrent" in pg_am, caller should
	 * have acquired exclusive lock on index relation.	We need no locking
	 * here.
	 */

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

	/* adjust any scans that will be affected by this deletion */
	/* NB: this works only for scans in *this* backend! */
	gistadjscans(r, GISTOP_DEL, blkno, offnum);

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

	PageIndexTupleDelete(page, offnum);

	WriteBuffer(buf);
}

/*
 * Bulk deletion of all index entries pointing to a set of heap tuples.
 * The set of target tuples is specified via a callback routine that tells
 * whether any given heap tuple (identified by ItemPointer) is being deleted.
 *
 * Result: a palloc'd struct containing statistical info for VACUUM displays.
 */
Datum
gistbulkdelete(PG_FUNCTION_ARGS)
{
	Relation	rel = (Relation) PG_GETARG_POINTER(0);
	IndexBulkDeleteCallback callback = (IndexBulkDeleteCallback) PG_GETARG_POINTER(1);
	void	   *callback_state = (void *) PG_GETARG_POINTER(2);
	IndexBulkDeleteResult *result;
	BlockNumber num_pages;
	double		tuples_removed;
	double		num_index_tuples;
	IndexScanDesc iscan;

	tuples_removed = 0;
	num_index_tuples = 0;

	/*
	 * Since GIST is not marked "amconcurrent" in pg_am, caller should
	 * have acquired exclusive lock on index relation.	We need no locking
	 * here.
	 */

	/*
	 * XXX generic implementation --- should be improved!
	 */

	/* walk through the entire index */
	iscan = index_beginscan(NULL, rel, SnapshotAny, 0, (ScanKey) NULL);
	/* including killed tuples */
	iscan->ignore_killed_tuples = false;

	while (index_getnext_indexitem(iscan, ForwardScanDirection))
	{
		if (callback(&iscan->xs_ctup.t_self, callback_state))
		{
			ItemPointerData indextup = iscan->currentItemData;
			BlockNumber blkno;
			OffsetNumber offnum;
			Buffer		buf;
			Page		page;

			blkno = ItemPointerGetBlockNumber(&indextup);
			offnum = ItemPointerGetOffsetNumber(&indextup);

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

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

			PageIndexTupleDelete(page, offnum);

			WriteBuffer(buf);

			tuples_removed += 1;
		}
		else
			num_index_tuples += 1;
	}

	index_endscan(iscan);

	/* return statistics */
	num_pages = RelationGetNumberOfBlocks(rel);

	result = (IndexBulkDeleteResult *) palloc0(sizeof(IndexBulkDeleteResult));
	result->num_pages = num_pages;
	result->num_index_tuples = num_index_tuples;
	result->tuples_removed = tuples_removed;

	PG_RETURN_POINTER(result);
}


void
initGISTstate(GISTSTATE *giststate, Relation index)
{
	int			i;

	if (index->rd_att->natts > INDEX_MAX_KEYS)
		elog(ERROR, "numberOfAttributes %d > %d",
			 index->rd_att->natts, INDEX_MAX_KEYS);

	giststate->tupdesc = index->rd_att;

	for (i = 0; i < index->rd_att->natts; i++)
	{
		fmgr_info_copy(&(giststate->consistentFn[i]),
				   index_getprocinfo(index, i + 1, GIST_CONSISTENT_PROC),
					   CurrentMemoryContext);
		fmgr_info_copy(&(giststate->unionFn[i]),
					   index_getprocinfo(index, i + 1, GIST_UNION_PROC),
					   CurrentMemoryContext);
		fmgr_info_copy(&(giststate->compressFn[i]),
					 index_getprocinfo(index, i + 1, GIST_COMPRESS_PROC),
					   CurrentMemoryContext);
		fmgr_info_copy(&(giststate->decompressFn[i]),
				   index_getprocinfo(index, i + 1, GIST_DECOMPRESS_PROC),
					   CurrentMemoryContext);
		fmgr_info_copy(&(giststate->penaltyFn[i]),
					   index_getprocinfo(index, i + 1, GIST_PENALTY_PROC),
					   CurrentMemoryContext);
		fmgr_info_copy(&(giststate->picksplitFn[i]),
					index_getprocinfo(index, i + 1, GIST_PICKSPLIT_PROC),
					   CurrentMemoryContext);
		fmgr_info_copy(&(giststate->equalFn[i]),
					   index_getprocinfo(index, i + 1, GIST_EQUAL_PROC),
					   CurrentMemoryContext);
	}
}

void
freeGISTstate(GISTSTATE *giststate)
{
	/* no work */
}

#ifdef GIST_PAGEADDITEM
/*
** 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 or if the null status changes.
**
** XXX this only works for a single-column index tuple!
*/
static IndexTuple
gist_tuple_replacekey(Relation r, GISTENTRY entry, IndexTuple t)
{
	bool		IsNull;
	Datum		datum = index_getattr(t, 1, r->rd_att, &IsNull);

	/*
	 * If new entry fits in index tuple, copy it in.  To avoid worrying
	 * about null-value bitmask, pass it off to the general
	 * index_formtuple routine if either the previous or new value is
	 * NULL.
	 */
	if (!IsNull && DatumGetPointer(entry.key) != NULL &&
		(Size) entry.bytes <= ATTSIZE(datum, r, 1, IsNull))
	{
		memcpy(DatumGetPointer(datum),
			   DatumGetPointer(entry.key),
			   entry.bytes);
		/* clear out old size */
		t->t_info &= ~INDEX_SIZE_MASK;
		/* 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;

		isnull = DatumGetPointer(entry.key) != NULL ? ' ' : 'n';
		newtup = (IndexTuple) index_formtuple(tupDesc,
											  &(entry.key),
											  &isnull);
		newtup->t_tid = t->t_tid;
		return newtup;
	}
}
#endif

/*
** initialize a GiST entry with a decompressed version of key
*/
void
gistdentryinit(GISTSTATE *giststate, int nkey, GISTENTRY *e,
			   Datum k, Relation r, Page pg, OffsetNumber o,
			   int b, bool l, bool isNull)
{
	if (b && !isNull)
	{
		GISTENTRY  *dep;

		gistentryinit(*e, k, r, pg, o, b, l);
		dep = (GISTENTRY *)
			DatumGetPointer(FunctionCall1(&giststate->decompressFn[nkey],
										  PointerGetDatum(e)));
		/* decompressFn may just return the given pointer */
		if (dep != e)
		{
			gistentryinit(*e, dep->key, dep->rel, dep->page, dep->offset,
						  dep->bytes, dep->leafkey);
			pfree(dep);
		}
	}
	else
		gistentryinit(*e, (Datum) 0, r, pg, o, 0, l);
}


/*
** initialize a GiST entry with a compressed version of key
*/
static void
gistcentryinit(GISTSTATE *giststate, int nkey,
			   GISTENTRY *e, Datum k, Relation r,
			   Page pg, OffsetNumber o, int b, bool l, bool isNull)
{
	if (!isNull)
	{
		GISTENTRY  *cep;

		gistentryinit(*e, k, r, pg, o, b, l);
		cep = (GISTENTRY *)
			DatumGetPointer(FunctionCall1(&giststate->compressFn[nkey],
										  PointerGetDatum(e)));
		/* compressFn may just return the given pointer */
		if (cep != e)
		{
			gistentryinit(*e, cep->key, cep->rel, cep->page, cep->offset,
						  cep->bytes, cep->leafkey);
			pfree(cep);
		}
	}
	else
		gistentryinit(*e, (Datum) 0, r, pg, o, 0, l);
}

static IndexTuple
gistFormTuple(GISTSTATE *giststate, Relation r,
			  Datum attdata[], int datumsize[], bool isnull[])
{
	IndexTuple	tup;
	char		isnullchar[INDEX_MAX_KEYS];
	bool		whatfree[INDEX_MAX_KEYS];
	GISTENTRY	centry[INDEX_MAX_KEYS];
	Datum		compatt[INDEX_MAX_KEYS];
	int			j;

	for (j = 0; j < r->rd_att->natts; j++)
	{
		if (isnull[j])
		{
			isnullchar[j] = 'n';
			compatt[j] = (Datum) 0;
			whatfree[j] = FALSE;
		}
		else
		{
			gistcentryinit(giststate, j, &centry[j], attdata[j],
					   (Relation) NULL, (Page) NULL, (OffsetNumber) NULL,
						   datumsize[j], FALSE, FALSE);
			isnullchar[j] = ' ';
			compatt[j] = centry[j].key;
			if (!isAttByVal(giststate, j))
			{
				whatfree[j] = TRUE;
				if (centry[j].key != attdata[j])
					pfree(DatumGetPointer(attdata[j]));
			}
			else
				whatfree[j] = FALSE;
		}
	}

	tup = (IndexTuple) index_formtuple(giststate->tupdesc, compatt, isnullchar);
	for (j = 0; j < r->rd_att->natts; j++)
		if (whatfree[j])
			pfree(DatumGetPointer(compatt[j]));

	return tup;
}

static void
gistDeCompressAtt(GISTSTATE *giststate, Relation r, IndexTuple tuple, Page p,
	OffsetNumber o, GISTENTRY attdata[], bool decompvec[], bool isnull[])
{
	int			i;
	Datum		datum;

	for (i = 0; i < r->rd_att->natts; i++)
	{
		datum = index_getattr(tuple, i + 1, giststate->tupdesc, &isnull[i]);
		gistdentryinit(giststate, i, &attdata[i],
					   datum, r, p, o,
					   ATTSIZE(datum, giststate->tupdesc, i + 1, isnull[i]), FALSE, isnull[i]);
		if (isAttByVal(giststate, i))
			decompvec[i] = FALSE;
		else
		{
			if (attdata[i].key == datum || isnull[i])
				decompvec[i] = FALSE;
			else
				decompvec[i] = TRUE;
		}
	}
}

static void
gistFreeAtt(Relation r, GISTENTRY attdata[], bool decompvec[])
{
	int			i;

	for (i = 0; i < r->rd_att->natts; i++)
		if (decompvec[i])
			pfree(DatumGetPointer(attdata[i].key));
}

static void
gistpenalty(GISTSTATE *giststate, int attno,
			GISTENTRY *key1, bool isNull1,
			GISTENTRY *key2, bool isNull2, float *penalty)
{
	if (giststate->penaltyFn[attno].fn_strict && (isNull1 || isNull2))
		*penalty = 0.0;
	else
		FunctionCall3(&giststate->penaltyFn[attno],
					  PointerGetDatum(key1),
					  PointerGetDatum(key2),
					  PointerGetDatum(penalty));
}

#ifdef GISTDEBUG
static void
gist_dumptree(Relation r, int level, BlockNumber blk, OffsetNumber coff)
{
	Buffer		buffer;
	Page		page;
	GISTPageOpaque opaque;
	IndexTuple	which;
	ItemId		iid;
	OffsetNumber i,
				maxoff;
	BlockNumber cblk;
	char	   *pred;

	pred = (char *) palloc(sizeof(char) * level + 1);
	MemSet(pred, '\t', level);
	pred[level] = '\0';

	buffer = ReadBuffer(r, blk);
	page = (Page) BufferGetPage(buffer);
	opaque = (GISTPageOpaque) PageGetSpecialPointer(page);

	maxoff = PageGetMaxOffsetNumber(page);

	elog(DEBUG4, "%sPage: %d %s blk: %d maxoff: %d free: %d", pred,
		 coff, (opaque->flags & F_LEAF) ? "LEAF" : "INTE", (int) blk,
		 (int) maxoff, PageGetFreeSpace(page));

	for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
	{
		iid = PageGetItemId(page, i);
		which = (IndexTuple) PageGetItem(page, iid);
		cblk = ItemPointerGetBlockNumber(&(which->t_tid));
#ifdef PRINTTUPLE
		elog(DEBUG4, "%s  Tuple. blk: %d size: %d", pred, (int) cblk,
			 IndexTupleSize(which));
#endif

		if (!(opaque->flags & F_LEAF))
			gist_dumptree(r, level + 1, cblk, i);
	}
	ReleaseBuffer(buffer);
	pfree(pred);
}
#endif   /* defined GISTDEBUG */

void
gist_redo(XLogRecPtr lsn, XLogRecord *record)
{
	elog(PANIC, "gist_redo: unimplemented");
}

void
gist_undo(XLogRecPtr lsn, XLogRecord *record)
{
	elog(PANIC, "gist_undo: unimplemented");
}

void
gist_desc(char *buf, uint8 xl_info, char *rec)
{
}