/*-------------------------------------------------------------------------
 *
 * gist.c
 *	  interface routines for the postgres GiST index access method.
 *
 *
 * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *	  $PostgreSQL: pgsql/src/backend/access/gist/gist.c,v 1.118 2005/06/06 17:01:21 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/genam.h"
#include "access/gist_private.h"
#include "access/gistscan.h"
#include "access/heapam.h"
#include "catalog/index.h"
#include "commands/vacuum.h"
#include "miscadmin.h"
#include "utils/memutils.h"


#undef GIST_PAGEADDITEM

#define ATTSIZE(datum, tupdesc, i, isnull) \
	( \
		(isnull) ? 0 : \
			att_addlength(0, (tupdesc)->attrs[(i)-1]->attlen, (datum)) \
	)

/* result's status */
#define INSERTED	0x01
#define SPLITED		0x02

/* group flags ( in gistSplit ) */
#define LEFT_ADDED	0x01
#define RIGHT_ADDED 0x02
#define BOTH_ADDED	( LEFT_ADDED | RIGHT_ADDED )

/*
 * This defines only for shorter code, used in gistgetadjusted
 * and gistadjsubkey only
 */
#define FILLITEM(evp, isnullkey, okey, okeyb, rkey, rkeyb)	 do { \
	if (isnullkey) {											  \
		gistentryinit((evp), rkey, r, NULL,						  \
					  (OffsetNumber) 0, rkeyb, FALSE);			  \
	} else {													  \
		gistentryinit((evp), okey, r, NULL,						  \
					  (OffsetNumber) 0, okeyb, FALSE);			  \
	}															  \
} while(0)

#define FILLEV(isnull1, key1, key1b, isnull2, key2, key2b) do { \
	FILLITEM(*ev0p, isnull1, key1, key1b, key2, key2b);		\
	FILLITEM(*ev1p, isnull2, key2, key2b, key1, key1b);		\
} while(0);

/* Working state for gistbuild and its callback */
typedef struct
{
	GISTSTATE	giststate;
	int			numindexattrs;
	double		indtuples;
	MemoryContext tmpCxt;
} GISTBuildState;


/* non-export function prototypes */
static void gistbuildCallback(Relation index,
				  HeapTuple htup,
				  Datum *values,
				  bool *isnull,
				  bool tupleIsAlive,
				  void *state);
static void gistdoinsert(Relation r,
			 IndexTuple itup,
			 GISTSTATE *GISTstate);
static int gistlayerinsert(Relation r, BlockNumber blkno,
				IndexTuple **itup,
				int *len,
				GISTSTATE *giststate);
static OffsetNumber gistwritebuffer(Relation r,
				Page page,
				IndexTuple *itup,
				int len,
				OffsetNumber off);
static bool gistnospace(Page page, IndexTuple *itvec, int len);
static IndexTuple *gistreadbuffer(Buffer buffer, int *len);
static IndexTuple *gistjoinvector(
			   IndexTuple *itvec, int *len,
			   IndexTuple *additvec, int addlen);
static IndexTuple gistunion(Relation r, IndexTuple *itvec,
		  int len, GISTSTATE *giststate);

static IndexTuple gistgetadjusted(Relation r,
				IndexTuple oldtup,
				IndexTuple addtup,
				GISTSTATE *giststate);
static int gistfindgroup(GISTSTATE *giststate,
			  GISTENTRY *valvec, GIST_SPLITVEC *spl);
static void gistadjsubkey(Relation r,
			  IndexTuple *itup, int *len,
			  GIST_SPLITVEC *v,
			  GISTSTATE *giststate);
static IndexTuple gistFormTuple(GISTSTATE *giststate,
			Relation r, Datum *attdata, int *datumsize, bool *isnull);
static IndexTuple *gistSplit(Relation r,
		  Buffer buffer,
		  IndexTuple *itup,
		  int *len,
		  GISTSTATE *giststate);
static void gistnewroot(Relation r, IndexTuple *itup, int len);
static void GISTInitBuffer(Buffer b, uint32 f);
static OffsetNumber gistchoose(Relation r, Page p,
		   IndexTuple it,
		   GISTSTATE *giststate);
static void gistdelete(Relation r, ItemPointer tid);

#ifdef GIST_PAGEADDITEM
static IndexTuple gist_tuple_replacekey(Relation r,
					  GISTENTRY entry, IndexTuple t);
#endif
static void gistcentryinit(GISTSTATE *giststate, int nkey,
			   GISTENTRY *e, Datum k,
			   Relation r, Page pg,
			   OffsetNumber o, int b, bool l, bool isNull);
static void gistDeCompressAtt(GISTSTATE *giststate, Relation r,
							  IndexTuple tuple, Page p, OffsetNumber o,
							  GISTENTRY *attdata, bool *isnull);
static void gistpenalty(GISTSTATE *giststate, int attno,
			GISTENTRY *key1, bool isNull1,
			GISTENTRY *key2, bool isNull2,
			float *penalty);

#undef GISTDEBUG

#ifdef GISTDEBUG
static void gist_dumptree(Relation r, int level, BlockNumber blk, OffsetNumber coff);
#endif

/*
 * Create and return a temporary memory context for use by GiST. We
 * _always_ invoke user-provided methods in a temporary memory
 * context, so that memory leaks in those functions cannot cause
 * problems. Also, we use some additional temporary contexts in the
 * GiST code itself, to avoid the need to do some awkward manual
 * memory management.
 */
MemoryContext                                                                                 
createTempGistContext(void)                                                                   
{                                                                                             
    return AllocSetContextCreate(CurrentMemoryContext,                                        
                                 "GiST temporary context",                                    
                                 ALLOCSET_DEFAULT_MINSIZE,                                    
                                 ALLOCSET_DEFAULT_INITSIZE,                                   
                                 ALLOCSET_DEFAULT_MAXSIZE);                                   
}                                                                                             

/*
 * Routine to build an index.  Basically calls insert over and over.
 *
 * XXX: it would be nice to implement some sort of bulk-loading
 * algorithm, but it is not clear how to do that.
 */
Datum
gistbuild(PG_FUNCTION_ARGS)
{
	Relation	heap = (Relation) PG_GETARG_POINTER(0);
	Relation	index = (Relation) PG_GETARG_POINTER(1);
	IndexInfo  *indexInfo = (IndexInfo *) PG_GETARG_POINTER(2);
	double		reltuples;
	GISTBuildState buildstate;
	Buffer		buffer;

	/*
	 * We expect to be called exactly once for any index relation. If
	 * that's not the case, big trouble's what we have.
	 */
	if (RelationGetNumberOfBlocks(index) != 0)
		elog(ERROR, "index \"%s\" already contains data",
			 RelationGetRelationName(index));

	/* no locking is needed */
	initGISTstate(&buildstate.giststate, index);

	/* initialize the root page */
	buffer = ReadBuffer(index, P_NEW);
	GISTInitBuffer(buffer, F_LEAF);
	WriteBuffer(buffer);

	/* build the index */
	buildstate.numindexattrs = indexInfo->ii_NumIndexAttrs;
	buildstate.indtuples = 0;
	/*
	 * create a temporary memory context that is reset once for each
	 * tuple inserted into the index
	 */
	buildstate.tmpCxt = createTempGistContext();

	/* do the heap scan */
	reltuples = IndexBuildHeapScan(heap, index, indexInfo,
								   gistbuildCallback, (void *) &buildstate);

	/* okay, all heap tuples are indexed */
	MemoryContextDelete(buildstate.tmpCxt);

	/* since we just counted the # of tuples, may as well update stats */
	IndexCloseAndUpdateStats(heap, reltuples, index, buildstate.indtuples);

	freeGISTstate(&buildstate.giststate);

#ifdef GISTDEBUG
	gist_dumptree(index, 0, GIST_ROOT_BLKNO, 0);
#endif
	PG_RETURN_VOID();
}

/*
 * Per-tuple callback from IndexBuildHeapScan
 */
static void
gistbuildCallback(Relation index,
				  HeapTuple htup,
				  Datum *values,
				  bool *isnull,
				  bool tupleIsAlive,
				  void *state)
{
	GISTBuildState *buildstate = (GISTBuildState *) state;
	IndexTuple	itup;
	GISTENTRY	tmpcentry;
	int			i;
	MemoryContext oldCxt;

	/* GiST cannot index tuples with leading NULLs */
	if (isnull[0])
		return;

	oldCxt = MemoryContextSwitchTo(buildstate->tmpCxt);

	/* immediately compress keys to normalize */
	for (i = 0; i < buildstate->numindexattrs; i++)
	{
		if (isnull[i])
			values[i] = (Datum) 0;
		else
		{
			gistcentryinit(&buildstate->giststate, i, &tmpcentry, values[i],
						   NULL, NULL, (OffsetNumber) 0,
						   -1 /* size is currently bogus */, TRUE, FALSE);
			values[i] = tmpcentry.key;
		}
	}

	/* form an index tuple and point it at the heap tuple */
	itup = index_form_tuple(buildstate->giststate.tupdesc, values, isnull);
	itup->t_tid = htup->t_self;

	/*
	 * Since we already have the index relation locked, we call
	 * gistdoinsert directly.  Normal access method calls dispatch through
	 * gistinsert, which locks the relation for write.	This is the right
	 * thing to do if you're inserting single tups, but not when you're
	 * initializing the whole index at once.
	 */
	gistdoinsert(index, itup, &buildstate->giststate);

	buildstate->indtuples += 1;
	MemoryContextSwitchTo(oldCxt);
	MemoryContextReset(buildstate->tmpCxt);
}

/*
 *	gistinsert -- wrapper for GiST tuple insertion.
 *
 *	  This is the public interface routine for tuple insertion in GiSTs.
 *	  It doesn't do any work; just locks the relation and passes the buck.
 */
Datum
gistinsert(PG_FUNCTION_ARGS)
{
	Relation	r = (Relation) PG_GETARG_POINTER(0);
	Datum	   *values = (Datum *) PG_GETARG_POINTER(1);
	bool	   *isnull = (bool *) PG_GETARG_POINTER(2);
	ItemPointer ht_ctid = (ItemPointer) PG_GETARG_POINTER(3);
#ifdef NOT_USED
	Relation	heapRel = (Relation) PG_GETARG_POINTER(4);
	bool		checkUnique = PG_GETARG_BOOL(5);
#endif
	IndexTuple	itup;
	GISTSTATE	giststate;
	GISTENTRY	tmpentry;
	int			i;
	MemoryContext oldCxt;
	MemoryContext insertCxt;

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

	/* GiST cannot index tuples with leading NULLs */
	if (isnull[0])
		PG_RETURN_BOOL(false);

	insertCxt = createTempGistContext();
	oldCxt = MemoryContextSwitchTo(insertCxt);

	initGISTstate(&giststate, r);

	/* immediately compress keys to normalize */
	for (i = 0; i < r->rd_att->natts; i++)
	{
		if (isnull[i])
			values[i] = (Datum) 0;
		else
		{
			gistcentryinit(&giststate, i, &tmpentry, values[i],
						   NULL, NULL, (OffsetNumber) 0,
						   -1 /* size is currently bogus */, TRUE, FALSE);
			values[i] = tmpentry.key;
		}
	}
	itup = index_form_tuple(giststate.tupdesc, values, isnull);
	itup->t_tid = *ht_ctid;

	gistdoinsert(r, itup, &giststate);

	/* cleanup */
	freeGISTstate(&giststate);
	MemoryContextSwitchTo(oldCxt);
	MemoryContextDelete(insertCxt);

	PG_RETURN_BOOL(true);
}

#ifdef GIST_PAGEADDITEM
/*
 * Take a compressed entry, and install it on a page.  Since we now know
 * where the entry will live, we decompress it and recompress it using
 * that knowledge (some compression routines may want to fish around
 * on the page, for example, or do something special for leaf nodes.)
 */
static OffsetNumber
gistPageAddItem(GISTSTATE *giststate,
				Relation r,
				Page page,
				Item item,
				Size size,
				OffsetNumber offsetNumber,
				ItemIdFlags flags,
				GISTENTRY *dentry,
				IndexTuple *newtup)
{
	GISTENTRY	tmpcentry;
	IndexTuple	itup = (IndexTuple) item;
	OffsetNumber retval;
	Datum		datum;
	bool		IsNull;

	/*
	 * recompress the item given that we now know the exact page and
	 * offset for insertion
	 */
	datum = index_getattr(itup, 1, r->rd_att, &IsNull);
	gistdentryinit(giststate, 0, dentry, datum,
				   (Relation) 0, (Page) 0,
				   (OffsetNumber) InvalidOffsetNumber,
				   ATTSIZE(datum, r, 1, IsNull),
				   FALSE, IsNull);
	gistcentryinit(giststate, 0, &tmpcentry, dentry->key, r, page,
				   offsetNumber, dentry->bytes, FALSE);
	*newtup = gist_tuple_replacekey(r, tmpcentry, itup);
	retval = PageAddItem(page, (Item) *newtup, IndexTupleSize(*newtup),
						 offsetNumber, flags);
	if (retval == InvalidOffsetNumber)
		elog(ERROR, "failed to add index item to \"%s\"",
			 RelationGetRelationName(r));
	return retval;
}
#endif

/*
 * Workhouse routine for doing insertion into a GiST index. Note that
 * this routine assumes it is invoked in a short-lived memory context,
 * so it does not bother releasing palloc'd allocations.
 */
static void
gistdoinsert(Relation r, IndexTuple itup, GISTSTATE *giststate)
{
	IndexTuple *instup;
	int			ret,
				len = 1;

	instup = (IndexTuple *) palloc(sizeof(IndexTuple));
	instup[0] = (IndexTuple) palloc(IndexTupleSize(itup));
	memcpy(instup[0], itup, IndexTupleSize(itup));

	ret = gistlayerinsert(r, GIST_ROOT_BLKNO, &instup, &len, giststate);
	if (ret & SPLITED)
		gistnewroot(r, instup, len);
}

static int
gistlayerinsert(Relation r, BlockNumber blkno,
				IndexTuple **itup,		/* in - out, has compressed entry */
				int *len,		/* in - out */
				GISTSTATE *giststate)
{
	Buffer		buffer;
	Page		page;
	int			ret;
	GISTPageOpaque opaque;

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

	if (!(opaque->flags & F_LEAF))
	{
        /*
         * This is an internal page, so continue to walk down the
         * tree. We find the child node that has the minimum insertion
         * penalty and recursively invoke ourselves to modify that
         * node. Once the recursive call returns, we may need to
         * adjust the parent node for two reasons: the child node
         * split, or the key in this node needs to be adjusted for the
         * newly inserted key below us.
         */
		ItemId		iid;
		BlockNumber nblkno;
		ItemPointerData oldtid;
		IndexTuple	oldtup;
		OffsetNumber child;

		child = gistchoose(r, page, *(*itup), giststate);
		iid = PageGetItemId(page, child);
		oldtup = (IndexTuple) PageGetItem(page, iid);
		nblkno = ItemPointerGetBlockNumber(&(oldtup->t_tid));

		/*
		 * After this call: 1. if child page was splited, then itup
		 * contains keys for each page 2. if  child page wasn't splited,
		 * then itup contains additional for adjustment of current key
		 */
		ret = gistlayerinsert(r, nblkno, itup, len, giststate);

		/* nothing inserted in child */
		if (!(ret & INSERTED))
		{
			ReleaseBuffer(buffer);
			return 0x00;
		}

		/* child did not split */
		if (!(ret & SPLITED))
		{
			IndexTuple	newtup = gistgetadjusted(r, oldtup, (*itup)[0], giststate);

			if (!newtup)
			{
				/* not need to update key */
				ReleaseBuffer(buffer);
				return 0x00;
			}

			(*itup)[0] = newtup;
		}

        /*
         * This node's key has been modified, either because a child
         * split occurred or because we needed to adjust our key for
         * an insert in a child node. Therefore, remove the old
         * version of this node's key.
         */
		ItemPointerSet(&oldtid, blkno, child);
		gistdelete(r, &oldtid);

		/*
		 * if child was splitted, new key for child will be inserted in
		 * the end list of child, so we must say to any scans that page is
		 * changed beginning from 'child' offset
		 */
		if (ret & SPLITED)
			gistadjscans(r, GISTOP_SPLIT, blkno, child);
	}

	ret = INSERTED;

	if (gistnospace(page, (*itup), *len))
	{
		/* no space for insertion */
		IndexTuple *itvec,
				   *newitup;
		int			tlen,
					oldlen;

		ret |= SPLITED;
		itvec = gistreadbuffer(buffer, &tlen);
		itvec = gistjoinvector(itvec, &tlen, (*itup), *len);
		oldlen = *len;
		newitup = gistSplit(r, buffer, itvec, &tlen, giststate);
		ReleaseBuffer(buffer);
		*itup = newitup;
		*len = tlen;			/* now tlen >= 2 */
	}
	else
	{
		/* enough space */
		OffsetNumber off,
					l;

		off = (PageIsEmpty(page)) ?
			FirstOffsetNumber
			:
			OffsetNumberNext(PageGetMaxOffsetNumber(page));
		l = gistwritebuffer(r, page, *itup, *len, off);
		WriteBuffer(buffer);

		if (*len > 1)
		{						/* previous insert ret & SPLITED != 0 */
			/*
			 * child was splited, so we must form union for insertion in
			 * parent
			 */
			IndexTuple	newtup = gistunion(r, (*itup), *len, giststate);
			ItemPointerSet(&(newtup->t_tid), blkno, 1);
			(*itup)[0] = newtup;
			*len = 1;
		}
	}

	return ret;
}

/*
 * Write itup vector to page, has no control of free space
 */
static OffsetNumber
gistwritebuffer(Relation r, Page page, IndexTuple *itup,
				int len, OffsetNumber off)
{
	OffsetNumber l = InvalidOffsetNumber;
	int			i;

	for (i = 0; i < len; i++)
	{
#ifdef GIST_PAGEADDITEM
		GISTENTRY	tmpdentry;
		IndexTuple	newtup;
		bool		IsNull;

		l = gistPageAddItem(giststate, r, page,
							(Item) itup[i], IndexTupleSize(itup[i]),
							off, LP_USED, &tmpdentry, &newtup);
		off = OffsetNumberNext(off);
#else
		l = PageAddItem(page, (Item) itup[i], IndexTupleSize(itup[i]),
						off, LP_USED);
		if (l == InvalidOffsetNumber)
			elog(ERROR, "failed to add index item to \"%s\"",
				 RelationGetRelationName(r));
#endif
	}
	return l;
}

/*
 * Check space for itup vector on page
 */
static bool
gistnospace(Page page, IndexTuple *itvec, int len)
{
	unsigned int size = 0;
	int			i;

	for (i = 0; i < len; i++)
		size += IndexTupleSize(itvec[i]) + sizeof(ItemIdData);

	return (PageGetFreeSpace(page) < size);
}

/*
 * Read buffer into itup vector
 */
static IndexTuple *
gistreadbuffer(Buffer buffer, int *len /* out */ )
{
	OffsetNumber i,
				maxoff;
	IndexTuple *itvec;
	Page		p = (Page) BufferGetPage(buffer);

	maxoff = PageGetMaxOffsetNumber(p);
	*len = maxoff;
	itvec = palloc(sizeof(IndexTuple) * maxoff);
	for (i = FirstOffsetNumber; i <= maxoff; i = OffsetNumberNext(i))
		itvec[i - 1] = (IndexTuple) PageGetItem(p, PageGetItemId(p, i));

	return itvec;
}

/*
 * join two vectors into one
 */
static IndexTuple *
gistjoinvector(IndexTuple *itvec, int *len, IndexTuple *additvec, int addlen)
{
	itvec = (IndexTuple *) repalloc((void *) itvec, sizeof(IndexTuple) * ((*len) + addlen));
	memmove(&itvec[*len], additvec, sizeof(IndexTuple) * addlen);
	*len += addlen;
	return itvec;
}

/*
 * Return an IndexTuple containing the result of applying the "union"
 * method to the specified IndexTuple vector.
 */
static IndexTuple
gistunion(Relation r, IndexTuple *itvec, int len, GISTSTATE *giststate)
{
	Datum		attr[INDEX_MAX_KEYS];
	bool		isnull[INDEX_MAX_KEYS];
	GistEntryVector *evec;
	int			i;
	GISTENTRY	centry[INDEX_MAX_KEYS];

	evec = (GistEntryVector *) palloc(((len == 1) ? 2 : len) * sizeof(GISTENTRY) + GEVHDRSZ);

	for (i = 0; i < r->rd_att->natts; i++)
	{
		Datum		datum;
		int			j;
		int			real_len;

		real_len = 0;
		for (j = 0; j < len; j++)
		{
			bool		IsNull;
			datum = index_getattr(itvec[j], i + 1, giststate->tupdesc, &IsNull);
			if (IsNull)
				continue;

			gistdentryinit(giststate, i,
						   &(evec->vector[real_len]),
						   datum,
						   NULL, NULL, (OffsetNumber) 0,
						   ATTSIZE(datum, giststate->tupdesc, i + 1, IsNull),
						   FALSE, IsNull);
			real_len++;
		}

		/* If this tuple vector was all NULLs, the union is NULL */
		if (real_len == 0)
		{
			attr[i] = (Datum) 0;
			isnull[i] = TRUE;
		}
		else
		{
			int datumsize;

			if (real_len == 1)
			{
				evec->n = 2;
				gistentryinit(evec->vector[1],
							  evec->vector[0].key, r, NULL,
							  (OffsetNumber) 0, evec->vector[0].bytes, FALSE);
			}
			else
				evec->n = real_len;

			/* Compress the result of the union and store in attr array */
			datum = FunctionCall2(&giststate->unionFn[i],
								  PointerGetDatum(evec),
								  PointerGetDatum(&datumsize));

			gistcentryinit(giststate, i, &centry[i], datum,
						   NULL, NULL, (OffsetNumber) 0,
						   datumsize, FALSE, FALSE);
			isnull[i] = FALSE;
			attr[i] = centry[i].key;
		}
	}

	return index_form_tuple(giststate->tupdesc, attr, isnull);
}


/*
 * Forms union of oldtup and addtup, if union == oldtup then return NULL
 */
static IndexTuple
gistgetadjusted(Relation r, IndexTuple oldtup, IndexTuple addtup, GISTSTATE *giststate)
{
	GistEntryVector *evec;
	bool		neednew = false;
	bool		isnull[INDEX_MAX_KEYS];
	Datum		attr[INDEX_MAX_KEYS];
	GISTENTRY	centry[INDEX_MAX_KEYS],
				oldatt[INDEX_MAX_KEYS],
				addatt[INDEX_MAX_KEYS],
			   *ev0p,
			   *ev1p;
	bool		oldisnull[INDEX_MAX_KEYS],
				addisnull[INDEX_MAX_KEYS];
	IndexTuple	newtup = NULL;
	int			i;

	evec = palloc(2 * sizeof(GISTENTRY) + GEVHDRSZ);
	evec->n = 2;
	ev0p = &(evec->vector[0]);
	ev1p = &(evec->vector[1]);

	gistDeCompressAtt(giststate, r, oldtup, NULL,
					  (OffsetNumber) 0, oldatt, oldisnull);

	gistDeCompressAtt(giststate, r, addtup, NULL,
					  (OffsetNumber) 0, addatt, addisnull);

	for (i = 0; i < r->rd_att->natts; i++)
	{
		if (oldisnull[i] && addisnull[i])
		{
			attr[i] = (Datum) 0;
			isnull[i] = TRUE;
		}
		else
		{
			Datum		datum;
			int			datumsize;

			FILLEV(oldisnull[i], oldatt[i].key, oldatt[i].bytes,
				   addisnull[i], addatt[i].key, addatt[i].bytes);

			datum = FunctionCall2(&giststate->unionFn[i],
								  PointerGetDatum(evec),
								  PointerGetDatum(&datumsize));

			if (oldisnull[i] || addisnull[i])
			{
				if (oldisnull[i])
					neednew = true;
			}
			else
			{
				bool	result;

				FunctionCall3(&giststate->equalFn[i],
							  ev0p->key,
							  datum,
							  PointerGetDatum(&result));

				if (!result)
					neednew = true;
			}

			gistcentryinit(giststate, i, &centry[i], datum,
						   NULL, NULL, (OffsetNumber) 0,
						   datumsize, FALSE, FALSE);

			attr[i] = centry[i].key;
			isnull[i] = FALSE;
		}
	}

	if (neednew)
	{
		/* need to update key */
		newtup = index_form_tuple(giststate->tupdesc, attr, isnull);
		newtup->t_tid = oldtup->t_tid;
	}

	return newtup;
}

static void
gistunionsubkey(Relation r, GISTSTATE *giststate, IndexTuple *itvec, GIST_SPLITVEC *spl)
{
	int lr;

	for (lr = 0; lr < 2; lr++)
	{
		OffsetNumber *entries;
		int			i;
		Datum	   *attr;
		int			len,
					*attrsize;
		bool	   *isnull;
		GistEntryVector *evec;

		if (lr)
		{
			attrsize = spl->spl_lattrsize;
			attr = spl->spl_lattr;
			len = spl->spl_nleft;
			entries = spl->spl_left;
			isnull = spl->spl_lisnull;
		}
		else
		{
			attrsize = spl->spl_rattrsize;
			attr = spl->spl_rattr;
			len = spl->spl_nright;
			entries = spl->spl_right;
			isnull = spl->spl_risnull;
		}

		evec = palloc(((len == 1) ? 2 : len) * sizeof(GISTENTRY) + GEVHDRSZ);

		for (i = 1; i < r->rd_att->natts; i++)
		{
			int			j;
			Datum		datum;
			int			datumsize;
			int			real_len;

			real_len = 0;
			for (j = 0; j < len; j++)
			{
				bool		IsNull;

				if (spl->spl_idgrp[entries[j]])
					continue;
				datum = index_getattr(itvec[entries[j] - 1], i + 1,
									  giststate->tupdesc, &IsNull);
				if (IsNull)
					continue;
				gistdentryinit(giststate, i,
							   &(evec->vector[real_len]),
							   datum,
							   NULL, NULL, (OffsetNumber) 0,
							   ATTSIZE(datum, giststate->tupdesc, i + 1, IsNull),
							   FALSE, IsNull);
				real_len++;

			}

			if (real_len == 0)
			{
				datum = (Datum) 0;
				datumsize = 0;
				isnull[i] = true;
			}
			else
			{
				/*
				 * evec->vector[0].bytes may be not defined, so form union
				 * with itself
				 */
				if (real_len == 1)
				{
					evec->n = 2;
					memcpy(&(evec->vector[1]), &(evec->vector[0]),
						   sizeof(GISTENTRY));
				}
				else
					evec->n = real_len;
				datum = FunctionCall2(&giststate->unionFn[i],
									  PointerGetDatum(evec),
									  PointerGetDatum(&datumsize));
				isnull[i] = false;
			}

			attr[i] = datum;
			attrsize[i] = datumsize;
		}
	}
}

/*
 * find group in vector with equal value
 */
static int
gistfindgroup(GISTSTATE *giststate, GISTENTRY *valvec, GIST_SPLITVEC *spl)
{
	int			i;
	int			curid = 1;

	/*
	 * first key is always not null (see gistinsert), so we may not check
	 * for nulls
	 */
	for (i = 0; i < spl->spl_nleft; i++)
	{
		int j;
		int len;
		bool result;

		if (spl->spl_idgrp[spl->spl_left[i]])
			continue;
		len = 0;
		/* find all equal value in right part */
		for (j = 0; j < spl->spl_nright; j++)
		{
			if (spl->spl_idgrp[spl->spl_right[j]])
				continue;
			FunctionCall3(&giststate->equalFn[0],
						  valvec[spl->spl_left[i]].key,
						  valvec[spl->spl_right[j]].key,
						  PointerGetDatum(&result));
			if (result)
			{
				spl->spl_idgrp[spl->spl_right[j]] = curid;
				len++;
			}
		}
		/* find all other equal value in left part */
		if (len)
		{
			/* add current val to list of equal values */
			spl->spl_idgrp[spl->spl_left[i]] = curid;
			/* searching .. */
			for (j = i + 1; j < spl->spl_nleft; j++)
			{
				if (spl->spl_idgrp[spl->spl_left[j]])
					continue;
				FunctionCall3(&giststate->equalFn[0],
							  valvec[spl->spl_left[i]].key,
							  valvec[spl->spl_left[j]].key,
							  PointerGetDatum(&result));
				if (result)
				{
					spl->spl_idgrp[spl->spl_left[j]] = curid;
					len++;
				}
			}
			spl->spl_ngrp[curid] = len + 1;
			curid++;
		}
	}

	return curid;
}

/*
 * Insert equivalent tuples to left or right page with minimum
 * penalty
 */
static void
gistadjsubkey(Relation r,
			  IndexTuple *itup, /* contains compressed entry */
			  int *len,
			  GIST_SPLITVEC *v,
			  GISTSTATE *giststate)
{
	int			curlen;
	OffsetNumber *curwpos;
	GISTENTRY	entry,
				identry[INDEX_MAX_KEYS],
			   *ev0p,
			   *ev1p;
	float		lpenalty,
				rpenalty;
	GistEntryVector *evec;
	int			datumsize;
	bool		isnull[INDEX_MAX_KEYS];
	int			i,
				j;

	/* clear vectors */
	curlen = v->spl_nleft;
	curwpos = v->spl_left;
	for (i = 0; i < v->spl_nleft; i++)
	{
		if (v->spl_idgrp[v->spl_left[i]] == 0)
		{
			*curwpos = v->spl_left[i];
			curwpos++;
		}
		else
			curlen--;
	}
	v->spl_nleft = curlen;

	curlen = v->spl_nright;
	curwpos = v->spl_right;
	for (i = 0; i < v->spl_nright; i++)
	{
		if (v->spl_idgrp[v->spl_right[i]] == 0)
		{
			*curwpos = v->spl_right[i];
			curwpos++;
		}
		else
			curlen--;
	}
	v->spl_nright = curlen;

	evec = palloc(2 * sizeof(GISTENTRY) + GEVHDRSZ);
	evec->n = 2;
	ev0p = &(evec->vector[0]);
	ev1p = &(evec->vector[1]);

	/* add equivalent tuple */
	for (i = 0; i < *len; i++)
	{
		Datum		datum;

		if (v->spl_idgrp[i + 1] == 0)	/* already inserted */
			continue;
		gistDeCompressAtt(giststate, r, itup[i], NULL, (OffsetNumber) 0,
						  identry, isnull);

		v->spl_ngrp[v->spl_idgrp[i + 1]]--;
		if (v->spl_ngrp[v->spl_idgrp[i + 1]] == 0 &&
			(v->spl_grpflag[v->spl_idgrp[i + 1]] & BOTH_ADDED) != BOTH_ADDED)
		{
			/* force last in group */
			rpenalty = 1.0;
			lpenalty = (v->spl_grpflag[v->spl_idgrp[i + 1]] & LEFT_ADDED) ? 2.0 : 0.0;
		}
		else
		{
			/* where? */
			for (j = 1; j < r->rd_att->natts; j++)
			{
				gistentryinit(entry, v->spl_lattr[j], r, NULL,
						   (OffsetNumber) 0, v->spl_lattrsize[j], FALSE);
				gistpenalty(giststate, j, &entry, v->spl_lisnull[j],
							&identry[j], isnull[j], &lpenalty);

				gistentryinit(entry, v->spl_rattr[j], r, NULL,
						   (OffsetNumber) 0, v->spl_rattrsize[j], FALSE);
				gistpenalty(giststate, j, &entry, v->spl_risnull[j],
							&identry[j], isnull[j], &rpenalty);

				if (lpenalty != rpenalty)
					break;
			}
		}

		/*
		 * add
		 * XXX: refactor this to avoid duplicating code
		 */
		if (lpenalty < rpenalty)
		{
			v->spl_grpflag[v->spl_idgrp[i + 1]] |= LEFT_ADDED;
			v->spl_left[v->spl_nleft] = i + 1;
			v->spl_nleft++;
			for (j = 1; j < r->rd_att->natts; j++)
			{
				if (isnull[j] && v->spl_lisnull[j])
				{
					v->spl_lattr[j] = (Datum) 0;
					v->spl_lattrsize[j] = 0;
				}
				else
				{
					FILLEV(v->spl_lisnull[j], v->spl_lattr[j], v->spl_lattrsize[j],
						   isnull[j], identry[j].key, identry[j].bytes);

					datum = FunctionCall2(&giststate->unionFn[j],
										  PointerGetDatum(evec),
										  PointerGetDatum(&datumsize));

					v->spl_lattr[j] = datum;
					v->spl_lattrsize[j] = datumsize;
					v->spl_lisnull[j] = false;
				}
			}
		}
		else
		{
			v->spl_grpflag[v->spl_idgrp[i + 1]] |= RIGHT_ADDED;
			v->spl_right[v->spl_nright] = i + 1;
			v->spl_nright++;
			for (j = 1; j < r->rd_att->natts; j++)
			{
				if (isnull[j] && v->spl_risnull[j])
				{
					v->spl_rattr[j] = (Datum) 0;
					v->spl_rattrsize[j] = 0;
				}
				else
				{
					FILLEV(v->spl_risnull[j], v->spl_rattr[j], v->spl_rattrsize[j],
						   isnull[j], identry[j].key, identry[j].bytes);

					datum = FunctionCall2(&giststate->unionFn[j],
										  PointerGetDatum(evec),
										  PointerGetDatum(&datumsize));

					v->spl_rattr[j] = datum;
					v->spl_rattrsize[j] = datumsize;
					v->spl_risnull[j] = false;
				}
			}
		}
	}
}

/*
 *	gistSplit -- split a page in the tree.
 */
static IndexTuple *
gistSplit(Relation r,
		  Buffer buffer,
		  IndexTuple *itup,		/* contains compressed entry */
		  int *len,
		  GISTSTATE *giststate)
{
	Page		p;
	Buffer		leftbuf,
				rightbuf;
	Page		left,
				right;
	IndexTuple *lvectup,
			   *rvectup,
			   *newtup;
	BlockNumber lbknum,
				rbknum;
	GISTPageOpaque opaque;
	GIST_SPLITVEC v;
	GistEntryVector *entryvec;
	int			i,
				nlen;

	p = (Page) BufferGetPage(buffer);
	opaque = (GISTPageOpaque) PageGetSpecialPointer(p);

	/*
	 * The root of the tree is the first block in the relation.  If we're
	 * about to split the root, we need to do some hocus-pocus to enforce
	 * this guarantee.
	 */
	if (BufferGetBlockNumber(buffer) == GIST_ROOT_BLKNO)
	{
		leftbuf = ReadBuffer(r, P_NEW);
		GISTInitBuffer(leftbuf, opaque->flags);
		lbknum = BufferGetBlockNumber(leftbuf);
		left = (Page) BufferGetPage(leftbuf);
	}
	else
	{
		leftbuf = buffer;
		IncrBufferRefCount(buffer);
		lbknum = BufferGetBlockNumber(buffer);
		left = (Page) PageGetTempPage(p, sizeof(GISTPageOpaqueData));
	}

	rightbuf = ReadBuffer(r, P_NEW);
	GISTInitBuffer(rightbuf, opaque->flags);
	rbknum = BufferGetBlockNumber(rightbuf);
	right = (Page) BufferGetPage(rightbuf);

	/* generate the item array */
	entryvec = palloc(GEVHDRSZ + (*len + 1) * sizeof(GISTENTRY));
	entryvec->n = *len + 1;

	for (i = 1; i <= *len; i++)
	{
		Datum		datum;
		bool		IsNull;

		datum = index_getattr(itup[i - 1], 1, giststate->tupdesc, &IsNull);
		gistdentryinit(giststate, 0, &(entryvec->vector[i]),
					   datum, r, p, i,
					   ATTSIZE(datum, giststate->tupdesc, 1, IsNull),
					   FALSE, IsNull);
	}

	/*
	 * now let the user-defined picksplit function set up the split
	 * vector; in entryvec have no null value!!
	 */
	FunctionCall2(&giststate->picksplitFn[0],
				  PointerGetDatum(entryvec),
				  PointerGetDatum(&v));

	/* compatibility with old code */
	if (v.spl_left[v.spl_nleft - 1] == InvalidOffsetNumber)
		v.spl_left[v.spl_nleft - 1] = (OffsetNumber) *len;
	if (v.spl_right[v.spl_nright - 1] == InvalidOffsetNumber)
		v.spl_right[v.spl_nright - 1] = (OffsetNumber) *len;

	v.spl_lattr[0] = v.spl_ldatum;
	v.spl_rattr[0] = v.spl_rdatum;
	v.spl_lisnull[0] = false;
	v.spl_risnull[0] = false;

	/*
	 * if index is multikey, then we must to try get smaller bounding box
	 * for subkey(s)
	 */
	if (r->rd_att->natts > 1)
	{
		int			MaxGrpId;

		v.spl_idgrp = (int *) palloc0(sizeof(int) * (*len + 1));
		v.spl_grpflag = (char *) palloc0(sizeof(char) * (*len + 1));
		v.spl_ngrp = (int *) palloc(sizeof(int) * (*len + 1));

		MaxGrpId = gistfindgroup(giststate, entryvec->vector, &v);

		/* form union of sub keys for each page (l,p) */
		gistunionsubkey(r, giststate, itup, &v);

		/*
		 * if possible, we insert equivalent tuples with control by
		 * penalty for a subkey(s)
		 */
		if (MaxGrpId > 1)
			gistadjsubkey(r, itup, len, &v, giststate);
	}

	/* form left and right vector */
	lvectup = (IndexTuple *) palloc(sizeof(IndexTuple) * v.spl_nleft);
	rvectup = (IndexTuple *) palloc(sizeof(IndexTuple) * v.spl_nright);

	for (i = 0; i < v.spl_nleft; i++)
		lvectup[i] = itup[v.spl_left[i] - 1];

	for (i = 0; i < v.spl_nright; i++)
		rvectup[i] = itup[v.spl_right[i] - 1];


	/* write on disk (may need another split) */
	if (gistnospace(right, rvectup, v.spl_nright))
	{
		nlen = v.spl_nright;
		newtup = gistSplit(r, rightbuf, rvectup, &nlen, giststate);
		ReleaseBuffer(rightbuf);
	}
	else
	{
		OffsetNumber l;

		l = gistwritebuffer(r, right, rvectup, v.spl_nright, FirstOffsetNumber);
		WriteBuffer(rightbuf);

		nlen = 1;
		newtup = (IndexTuple *) palloc(sizeof(IndexTuple) * 1);
		newtup[0] = gistFormTuple(giststate, r, v.spl_rattr, v.spl_rattrsize, v.spl_risnull);
		ItemPointerSet(&(newtup[0]->t_tid), rbknum, 1);
	}

	if (gistnospace(left, lvectup, v.spl_nleft))
	{
		int			llen = v.spl_nleft;
		IndexTuple *lntup;

		lntup = gistSplit(r, leftbuf, lvectup, &llen, giststate);
		ReleaseBuffer(leftbuf);

		newtup = gistjoinvector(newtup, &nlen, lntup, llen);
	}
	else
	{
		OffsetNumber l;

		l = gistwritebuffer(r, left, lvectup, v.spl_nleft, FirstOffsetNumber);
		if (BufferGetBlockNumber(buffer) != GIST_ROOT_BLKNO)
			PageRestoreTempPage(left, p);

		WriteBuffer(leftbuf);

		nlen += 1;
		newtup = (IndexTuple *) repalloc(newtup, sizeof(IndexTuple) * nlen);
		newtup[nlen - 1] = gistFormTuple(giststate, r, v.spl_lattr, v.spl_lattrsize, v.spl_lisnull);
		ItemPointerSet(&(newtup[nlen - 1]->t_tid), lbknum, 1);
	}

	*len = nlen;
	return newtup;
}

static void
gistnewroot(Relation r, IndexTuple *itup, int len)
{
	Buffer		b;
	Page		p;

	b = ReadBuffer(r, GIST_ROOT_BLKNO);
	GISTInitBuffer(b, 0);
	p = BufferGetPage(b);

	gistwritebuffer(r, p, itup, len, FirstOffsetNumber);
	WriteBuffer(b);
}

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

	pageSize = BufferGetPageSize(b);
	page = BufferGetPage(b);
	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;
	OffsetNumber which;
	float		sum_grow,
				which_grow[INDEX_MAX_KEYS];
	GISTENTRY	entry,
				identry[INDEX_MAX_KEYS];
	bool		isnull[INDEX_MAX_KEYS];

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

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

		sum_grow = 0;
		for (j = 0; j < r->rd_att->natts; j++)
		{
			Datum		datum;
			float		usize;
			bool		IsNull;

			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 (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;
			}
		}
	}

	return which;
}

/*
 * 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, NULL);
	/* including killed tuples */
	iscan->ignore_killed_tuples = false;

	while (index_getnext_indexitem(iscan, ForwardScanDirection))
	{
		vacuum_delay_point();

		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_form_tuple 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;
		bool		isnull;

		isnull = (DatumGetPointer(entry.key) == NULL);
		newtup = index_form_tuple(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);
	}
	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);
	}
	else
		gistentryinit(*e, (Datum) 0, r, pg, o, 0, l);
}

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

	for (i = 0; i < r->rd_att->natts; i++)
	{
		if (isnull[i])
			compatt[i] = (Datum) 0;
		else
		{
			gistcentryinit(giststate, i, &centry[i], attdata[i],
						   NULL, NULL, (OffsetNumber) 0,
						   datumsize[i], FALSE, FALSE);
			compatt[i] = centry[i].key;
		}
	}

	return index_form_tuple(giststate->tupdesc, compatt, isnull);
}

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

	for (i = 0; i < r->rd_att->natts; i++)
	{
		Datum 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]);
	}
}

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_desc(char *buf, uint8 xl_info, char *rec)
{
}
