Implement operator class parameters

PostgreSQL provides set of template index access methods, where opclasses have
much freedom in the semantics of indexing.  These index AMs are GiST, GIN,
SP-GiST and BRIN.  There opclasses define representation of keys, operations on
them and supported search strategies.  So, it's natural that opclasses may be
faced some tradeoffs, which require user-side decision.  This commit implements
opclass parameters allowing users to set some values, which tell opclass how to
index the particular dataset.

This commit doesn't introduce new storage in system catalog.  Instead it uses
pg_attribute.attoptions, which is used for table column storage options but
unused for index attributes.

In order to evade changing signature of each opclass support function, we
implement unified way to pass options to opclass support functions.  Options
are set to fn_expr as the constant bytea expression.  It's possible due to the
fact that opclass support functions are executed outside of expressions, so
fn_expr is unused for them.

This commit comes with some examples of opclass options usage.  We parametrize
signature length in GiST.  That applies to multiple opclasses: tsvector_ops,
gist__intbig_ops, gist_ltree_ops, gist__ltree_ops, gist_trgm_ops and
gist_hstore_ops.  Also we parametrize maximum number of integer ranges for
gist__int_ops.  However, the main future usage of this feature is expected
to be json, where users would be able to specify which way to index particular
json parts.

Catversion is bumped.

Discussion: https://postgr.es/m/d22c3a18-31c7-1879-fc11-4c1ce2f5e5af%40postgrespro.ru
Author: Nikita Glukhov, revised by me
Reviwed-by: Nikolay Shaplov, Robert Haas, Tom Lane, Tomas Vondra, Alvaro Herrera

1 files changed, 127 insertions, 100 deletions

diff --git a/contrib/pg_trgm/trgm_gist.c b/contrib/pg_trgm/trgm_gist.c
index 35a75c60668..9937ef92531 100644
--- a/contrib/pg_trgm/trgm_gist.c
+++ b/contrib/pg_trgm/trgm_gist.c
@@ -3,11 +3,23 @@
  */
 #include "postgres.h"
 
+#include "access/reloptions.h"
 #include "access/stratnum.h"
 #include "fmgr.h"
 #include "port/pg_bitutils.h"
 #include "trgm.h"
 
+/* gist_trgm_ops opclass options */
+typedef struct
+{
+	int32		vl_len_;		/* varlena header (do not touch directly!) */
+	int			siglen;			/* signature length in bytes */
+} TrgmGistOptions;
+
+#define LTREE_GET_ASIGLEN()		(PG_HAS_OPCLASS_OPTIONS() ? \
+								 ((TrgmGistOptions *) PG_GET_OPCLASS_OPTIONS())->siglen : \
+								 SIGLEN_DEFAULT)
+
 typedef struct
 {
 	/* most recent inputs to gtrgm_consistent */
@@ -37,6 +49,7 @@ PG_FUNCTION_INFO_V1(gtrgm_union);
 PG_FUNCTION_INFO_V1(gtrgm_same);
 PG_FUNCTION_INFO_V1(gtrgm_penalty);
 PG_FUNCTION_INFO_V1(gtrgm_picksplit);
+PG_FUNCTION_INFO_V1(gtrgm_options);
 
 
 Datum
@@ -53,20 +66,41 @@ gtrgm_out(PG_FUNCTION_ARGS)
 	PG_RETURN_DATUM(0);
 }
 
+static TRGM *
+gtrgm_alloc(bool isalltrue, int siglen, BITVECP sign)
+{
+	int			flag = SIGNKEY | (isalltrue ? ALLISTRUE : 0);
+	int			size = CALCGTSIZE(flag, siglen);
+	TRGM	   *res = palloc(size);
+
+	SET_VARSIZE(res, size);
+	res->flag = flag;
+
+	if (!isalltrue)
+	{
+		if (sign)
+			memcpy(GETSIGN(res), sign, siglen);
+		else
+			memset(GETSIGN(res), 0, siglen);
+	}
+
+	return res;
+}
+
 static void
-makesign(BITVECP sign, TRGM *a)
+makesign(BITVECP sign, TRGM *a, int siglen)
 {
 	int32		k,
 				len = ARRNELEM(a);
 	trgm	   *ptr = GETARR(a);
 	int32		tmp = 0;
 
-	MemSet((void *) sign, 0, sizeof(BITVEC));
-	SETBIT(sign, SIGLENBIT);	/* set last unused bit */
+	MemSet((void *) sign, 0, siglen);
+	SETBIT(sign, SIGLENBIT(siglen));	/* set last unused bit */
 	for (k = 0; k < len; k++)
 	{
 		CPTRGM(((char *) &tmp), ptr + k);
-		HASH(sign, tmp);
+		HASH(sign, tmp, siglen);
 	}
 }
 
@@ -74,6 +108,7 @@ Datum
 gtrgm_compress(PG_FUNCTION_ARGS)
 {
 	GISTENTRY  *entry = (GISTENTRY *) PG_GETARG_POINTER(0);
+	int			siglen = LTREE_GET_ASIGLEN();
 	GISTENTRY  *retval = entry;
 
 	if (entry->leafkey)
@@ -90,22 +125,17 @@ gtrgm_compress(PG_FUNCTION_ARGS)
 	else if (ISSIGNKEY(DatumGetPointer(entry->key)) &&
 			 !ISALLTRUE(DatumGetPointer(entry->key)))
 	{
-		int32		i,
-					len;
+		int32		i;
 		TRGM	   *res;
 		BITVECP		sign = GETSIGN(DatumGetPointer(entry->key));
 
-		LOOPBYTE
+		LOOPBYTE(siglen)
 		{
 			if ((sign[i] & 0xff) != 0xff)
 				PG_RETURN_POINTER(retval);
 		}
 
-		len = CALCGTSIZE(SIGNKEY | ALLISTRUE, 0);
-		res = (TRGM *) palloc(len);
-		SET_VARSIZE(res, len);
-		res->flag = SIGNKEY | ALLISTRUE;
-
+		res = gtrgm_alloc(true, siglen, sign);
 		retval = (GISTENTRY *) palloc(sizeof(GISTENTRY));
 		gistentryinit(*retval, PointerGetDatum(res),
 					  entry->rel, entry->page,
@@ -139,7 +169,7 @@ gtrgm_decompress(PG_FUNCTION_ARGS)
 }
 
 static int32
-cnt_sml_sign_common(TRGM *qtrg, BITVECP sign)
+cnt_sml_sign_common(TRGM *qtrg, BITVECP sign, int siglen)
 {
 	int32		count = 0;
 	int32		k,
@@ -150,7 +180,7 @@ cnt_sml_sign_common(TRGM *qtrg, BITVECP sign)
 	for (k = 0; k < len; k++)
 	{
 		CPTRGM(((char *) &tmp), ptr + k);
-		count += GETBIT(sign, HASHVAL(tmp));
+		count += GETBIT(sign, HASHVAL(tmp, siglen));
 	}
 
 	return count;
@@ -165,6 +195,7 @@ gtrgm_consistent(PG_FUNCTION_ARGS)
 
 	/* Oid		subtype = PG_GETARG_OID(3); */
 	bool	   *recheck = (bool *) PG_GETARG_POINTER(4);
+	int			siglen = LTREE_GET_ASIGLEN();
 	TRGM	   *key = (TRGM *) DatumGetPointer(entry->key);
 	TRGM	   *qtrg;
 	bool		res;
@@ -292,7 +323,7 @@ gtrgm_consistent(PG_FUNCTION_ARGS)
 			}
 			else
 			{					/* non-leaf contains signature */
-				int32		count = cnt_sml_sign_common(qtrg, GETSIGN(key));
+				int32		count = cnt_sml_sign_common(qtrg, GETSIGN(key), siglen);
 				int32		len = ARRNELEM(qtrg);
 
 				if (len == 0)
@@ -334,7 +365,7 @@ gtrgm_consistent(PG_FUNCTION_ARGS)
 				for (k = 0; k < len; k++)
 				{
 					CPTRGM(((char *) &tmp), ptr + k);
-					if (!GETBIT(sign, HASHVAL(tmp)))
+					if (!GETBIT(sign, HASHVAL(tmp, siglen)))
 					{
 						res = false;
 						break;
@@ -387,7 +418,7 @@ gtrgm_consistent(PG_FUNCTION_ARGS)
 					for (k = 0; k < len; k++)
 					{
 						CPTRGM(((char *) &tmp), ptr + k);
-						check[k] = GETBIT(sign, HASHVAL(tmp));
+						check[k] = GETBIT(sign, HASHVAL(tmp, siglen));
 					}
 					res = trigramsMatchGraph(cache->graph, check);
 					pfree(check);
@@ -417,6 +448,7 @@ gtrgm_distance(PG_FUNCTION_ARGS)
 
 	/* Oid		subtype = PG_GETARG_OID(3); */
 	bool	   *recheck = (bool *) PG_GETARG_POINTER(4);
+	int			siglen = LTREE_GET_ASIGLEN();
 	TRGM	   *key = (TRGM *) DatumGetPointer(entry->key);
 	TRGM	   *qtrg;
 	float8		res;
@@ -474,7 +506,7 @@ gtrgm_distance(PG_FUNCTION_ARGS)
 			}
 			else
 			{					/* non-leaf contains signature */
-				int32		count = cnt_sml_sign_common(qtrg, GETSIGN(key));
+				int32		count = cnt_sml_sign_common(qtrg, GETSIGN(key), siglen);
 				int32		len = ARRNELEM(qtrg);
 
 				res = (len == 0) ? -1.0 : 1.0 - ((float8) count) / ((float8) len);
@@ -490,7 +522,7 @@ gtrgm_distance(PG_FUNCTION_ARGS)
 }
 
 static int32
-unionkey(BITVECP sbase, TRGM *add)
+unionkey(BITVECP sbase, TRGM *add, int siglen)
 {
 	int32		i;
 
@@ -501,7 +533,7 @@ unionkey(BITVECP sbase, TRGM *add)
 		if (ISALLTRUE(add))
 			return 1;
 
-		LOOPBYTE
+		LOOPBYTE(siglen)
 			sbase[i] |= sadd[i];
 	}
 	else
@@ -512,7 +544,7 @@ unionkey(BITVECP sbase, TRGM *add)
 		for (i = 0; i < ARRNELEM(add); i++)
 		{
 			CPTRGM(((char *) &tmp), ptr + i);
-			HASH(sbase, tmp);
+			HASH(sbase, tmp, siglen);
 		}
 	}
 	return 0;
@@ -525,29 +557,22 @@ gtrgm_union(PG_FUNCTION_ARGS)
 	GistEntryVector *entryvec = (GistEntryVector *) PG_GETARG_POINTER(0);
 	int32		len = entryvec->n;
 	int		   *size = (int *) PG_GETARG_POINTER(1);
-	BITVEC		base;
+	int			siglen = LTREE_GET_ASIGLEN();
 	int32		i;
-	int32		flag = 0;
-	TRGM	   *result;
+	TRGM	   *result = gtrgm_alloc(false, siglen, NULL);
+	BITVECP		base = GETSIGN(result);
 
-	MemSet((void *) base, 0, sizeof(BITVEC));
 	for (i = 0; i < len; i++)
 	{
-		if (unionkey(base, GETENTRY(entryvec, i)))
+		if (unionkey(base, GETENTRY(entryvec, i), siglen))
 		{
-			flag = ALLISTRUE;
+			result->flag = ALLISTRUE;
+			SET_VARSIZE(result, CALCGTSIZE(ALLISTRUE, siglen));
 			break;
 		}
 	}
 
-	flag |= SIGNKEY;
-	len = CALCGTSIZE(flag, 0);
-	result = (TRGM *) palloc(len);
-	SET_VARSIZE(result, len);
-	result->flag = flag;
-	if (!ISALLTRUE(result))
-		memcpy((void *) GETSIGN(result), (void *) base, sizeof(BITVEC));
-	*size = len;
+	*size = VARSIZE(result);
 
 	PG_RETURN_POINTER(result);
 }
@@ -558,6 +583,7 @@ gtrgm_same(PG_FUNCTION_ARGS)
 	TRGM	   *a = (TRGM *) PG_GETARG_POINTER(0);
 	TRGM	   *b = (TRGM *) PG_GETARG_POINTER(1);
 	bool	   *result = (bool *) PG_GETARG_POINTER(2);
+	int			siglen = LTREE_GET_ASIGLEN();
 
 	if (ISSIGNKEY(a))
 	{							/* then b also ISSIGNKEY */
@@ -574,7 +600,7 @@ gtrgm_same(PG_FUNCTION_ARGS)
 						sb = GETSIGN(b);
 
 			*result = true;
-			LOOPBYTE
+			LOOPBYTE(siglen)
 			{
 				if (sa[i] != sb[i])
 				{
@@ -611,19 +637,19 @@ gtrgm_same(PG_FUNCTION_ARGS)
 }
 
 static int32
-sizebitvec(BITVECP sign)
+sizebitvec(BITVECP sign, int siglen)
 {
-	return pg_popcount(sign, SIGLEN);
+	return pg_popcount(sign, siglen);
 }
 
 static int
-hemdistsign(BITVECP a, BITVECP b)
+hemdistsign(BITVECP a, BITVECP b, int siglen)
 {
 	int			i,
 				diff,
 				dist = 0;
 
-	LOOPBYTE
+	LOOPBYTE(siglen)
 	{
 		diff = (unsigned char) (a[i] ^ b[i]);
 		/* Using the popcount functions here isn't likely to win */
@@ -633,19 +659,19 @@ hemdistsign(BITVECP a, BITVECP b)
 }
 
 static int
-hemdist(TRGM *a, TRGM *b)
+hemdist(TRGM *a, TRGM *b, int siglen)
 {
 	if (ISALLTRUE(a))
 	{
 		if (ISALLTRUE(b))
 			return 0;
 		else
-			return SIGLENBIT - sizebitvec(GETSIGN(b));
+			return SIGLENBIT(siglen) - sizebitvec(GETSIGN(b), siglen);
 	}
 	else if (ISALLTRUE(b))
-		return SIGLENBIT - sizebitvec(GETSIGN(a));
+		return SIGLENBIT(siglen) - sizebitvec(GETSIGN(a), siglen);
 
-	return hemdistsign(GETSIGN(a), GETSIGN(b));
+	return hemdistsign(GETSIGN(a), GETSIGN(b), siglen);
 }
 
 Datum
@@ -654,6 +680,7 @@ gtrgm_penalty(PG_FUNCTION_ARGS)
 	GISTENTRY  *origentry = (GISTENTRY *) PG_GETARG_POINTER(0); /* always ISSIGNKEY */
 	GISTENTRY  *newentry = (GISTENTRY *) PG_GETARG_POINTER(1);
 	float	   *penalty = (float *) PG_GETARG_POINTER(2);
+	int			siglen = LTREE_GET_ASIGLEN();
 	TRGM	   *origval = (TRGM *) DatumGetPointer(origentry->key);
 	TRGM	   *newval = (TRGM *) DatumGetPointer(newentry->key);
 	BITVECP		orig = GETSIGN(origval);
@@ -663,7 +690,7 @@ gtrgm_penalty(PG_FUNCTION_ARGS)
 	if (ISARRKEY(newval))
 	{
 		char	   *cache = (char *) fcinfo->flinfo->fn_extra;
-		TRGM	   *cachedVal = (TRGM *) (cache + MAXALIGN(sizeof(BITVEC)));
+		TRGM	   *cachedVal = (TRGM *) (cache + MAXALIGN(siglen));
 		Size		newvalsize = VARSIZE(newval);
 		BITVECP		sign;
 
@@ -677,12 +704,12 @@ gtrgm_penalty(PG_FUNCTION_ARGS)
 			char	   *newcache;
 
 			newcache = MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
-										  MAXALIGN(sizeof(BITVEC)) +
+										  MAXALIGN(siglen) +
 										  newvalsize);
 
-			makesign((BITVECP) newcache, newval);
+			makesign((BITVECP) newcache, newval, siglen);
 
-			cachedVal = (TRGM *) (newcache + MAXALIGN(sizeof(BITVEC)));
+			cachedVal = (TRGM *) (newcache + MAXALIGN(siglen));
 			memcpy(cachedVal, newval, newvalsize);
 
 			if (cache)
@@ -694,31 +721,32 @@ gtrgm_penalty(PG_FUNCTION_ARGS)
 		sign = (BITVECP) cache;
 
 		if (ISALLTRUE(origval))
-			*penalty = ((float) (SIGLENBIT - sizebitvec(sign))) / (float) (SIGLENBIT + 1);
+			*penalty = ((float) (SIGLENBIT(siglen) - sizebitvec(sign, siglen))) / (float) (SIGLENBIT(siglen) + 1);
 		else
-			*penalty = hemdistsign(sign, orig);
+			*penalty = hemdistsign(sign, orig, siglen);
 	}
 	else
-		*penalty = hemdist(origval, newval);
+		*penalty = hemdist(origval, newval, siglen);
 	PG_RETURN_POINTER(penalty);
 }
 
 typedef struct
 {
 	bool		allistrue;
-	BITVEC		sign;
+	BITVECP		sign;
 } CACHESIGN;
 
 static void
-fillcache(CACHESIGN *item, TRGM *key)
+fillcache(CACHESIGN *item, TRGM *key, BITVECP sign, int siglen)
 {
 	item->allistrue = false;
+	item->sign = sign;
 	if (ISARRKEY(key))
-		makesign(item->sign, key);
+		makesign(item->sign, key, siglen);
 	else if (ISALLTRUE(key))
 		item->allistrue = true;
 	else
-		memcpy((void *) item->sign, (void *) GETSIGN(key), sizeof(BITVEC));
+		memcpy((void *) item->sign, (void *) GETSIGN(key), siglen);
 }
 
 #define WISH_F(a,b,c) (double)( -(double)(((a)-(b))*((a)-(b))*((a)-(b)))*(c) )
@@ -739,19 +767,19 @@ comparecost(const void *a, const void *b)
 
 
 static int
-hemdistcache(CACHESIGN *a, CACHESIGN *b)
+hemdistcache(CACHESIGN *a, CACHESIGN *b, int siglen)
 {
 	if (a->allistrue)
 	{
 		if (b->allistrue)
 			return 0;
 		else
-			return SIGLENBIT - sizebitvec(b->sign);
+			return SIGLENBIT(siglen) - sizebitvec(b->sign, siglen);
 	}
 	else if (b->allistrue)
-		return SIGLENBIT - sizebitvec(a->sign);
+		return SIGLENBIT(siglen) - sizebitvec(a->sign, siglen);
 
-	return hemdistsign(a->sign, b->sign);
+	return hemdistsign(a->sign, b->sign, siglen);
 }
 
 Datum
@@ -760,6 +788,7 @@ gtrgm_picksplit(PG_FUNCTION_ARGS)
 	GistEntryVector *entryvec = (GistEntryVector *) PG_GETARG_POINTER(0);
 	OffsetNumber maxoff = entryvec->n - 2;
 	GIST_SPLITVEC *v = (GIST_SPLITVEC *) PG_GETARG_POINTER(1);
+	int			siglen = LTREE_GET_ASIGLEN();
 	OffsetNumber k,
 				j;
 	TRGM	   *datum_l,
@@ -778,19 +807,23 @@ gtrgm_picksplit(PG_FUNCTION_ARGS)
 	BITVECP		ptr;
 	int			i;
 	CACHESIGN  *cache;
+	char	   *cache_sign;
 	SPLITCOST  *costvector;
 
 	/* cache the sign data for each existing item */
 	cache = (CACHESIGN *) palloc(sizeof(CACHESIGN) * (maxoff + 2));
+	cache_sign = palloc(siglen * (maxoff + 2));
+
 	for (k = FirstOffsetNumber; k <= maxoff; k = OffsetNumberNext(k))
-		fillcache(&cache[k], GETENTRY(entryvec, k));
+		fillcache(&cache[k], GETENTRY(entryvec, k), &cache_sign[siglen * k],
+				  siglen);
 
 	/* now find the two furthest-apart items */
 	for (k = FirstOffsetNumber; k < maxoff; k = OffsetNumberNext(k))
 	{
 		for (j = OffsetNumberNext(k); j <= maxoff; j = OffsetNumberNext(j))
 		{
-			size_waste = hemdistcache(&(cache[j]), &(cache[k]));
+			size_waste = hemdistcache(&(cache[j]), &(cache[k]), siglen);
 			if (size_waste > waste)
 			{
 				waste = size_waste;
@@ -815,44 +848,22 @@ gtrgm_picksplit(PG_FUNCTION_ARGS)
 	v->spl_nright = 0;
 
 	/* form initial .. */
-	if (cache[seed_1].allistrue)
-	{
-		datum_l = (TRGM *) palloc(CALCGTSIZE(SIGNKEY | ALLISTRUE, 0));
-		SET_VARSIZE(datum_l, CALCGTSIZE(SIGNKEY | ALLISTRUE, 0));
-		datum_l->flag = SIGNKEY | ALLISTRUE;
-	}
-	else
-	{
-		datum_l = (TRGM *) palloc(CALCGTSIZE(SIGNKEY, 0));
-		SET_VARSIZE(datum_l, CALCGTSIZE(SIGNKEY, 0));
-		datum_l->flag = SIGNKEY;
-		memcpy((void *) GETSIGN(datum_l), (void *) cache[seed_1].sign, sizeof(BITVEC));
-	}
-	if (cache[seed_2].allistrue)
-	{
-		datum_r = (TRGM *) palloc(CALCGTSIZE(SIGNKEY | ALLISTRUE, 0));
-		SET_VARSIZE(datum_r, CALCGTSIZE(SIGNKEY | ALLISTRUE, 0));
-		datum_r->flag = SIGNKEY | ALLISTRUE;
-	}
-	else
-	{
-		datum_r = (TRGM *) palloc(CALCGTSIZE(SIGNKEY, 0));
-		SET_VARSIZE(datum_r, CALCGTSIZE(SIGNKEY, 0));
-		datum_r->flag = SIGNKEY;
-		memcpy((void *) GETSIGN(datum_r), (void *) cache[seed_2].sign, sizeof(BITVEC));
-	}
+	datum_l = gtrgm_alloc(cache[seed_1].allistrue, siglen, cache[seed_1].sign);
+	datum_r = gtrgm_alloc(cache[seed_2].allistrue, siglen, cache[seed_2].sign);
 
 	union_l = GETSIGN(datum_l);
 	union_r = GETSIGN(datum_r);
 	maxoff = OffsetNumberNext(maxoff);
-	fillcache(&cache[maxoff], GETENTRY(entryvec, maxoff));
+	fillcache(&cache[maxoff], GETENTRY(entryvec, maxoff),
+			  &cache_sign[siglen * maxoff], siglen);
+
 	/* sort before ... */
 	costvector = (SPLITCOST *) palloc(sizeof(SPLITCOST) * maxoff);
 	for (j = FirstOffsetNumber; j <= maxoff; j = OffsetNumberNext(j))
 	{
 		costvector[j - 1].pos = j;
-		size_alpha = hemdistcache(&(cache[seed_1]), &(cache[j]));
-		size_beta = hemdistcache(&(cache[seed_2]), &(cache[j]));
+		size_alpha = hemdistcache(&(cache[seed_1]), &(cache[j]), siglen);
+		size_beta = hemdistcache(&(cache[seed_2]), &(cache[j]), siglen);
 		costvector[j - 1].cost = abs(size_alpha - size_beta);
 	}
 	qsort((void *) costvector, maxoff, sizeof(SPLITCOST), comparecost);
@@ -878,36 +889,38 @@ gtrgm_picksplit(PG_FUNCTION_ARGS)
 			if (ISALLTRUE(datum_l) && cache[j].allistrue)
 				size_alpha = 0;
 			else
-				size_alpha = SIGLENBIT -
+				size_alpha = SIGLENBIT(siglen) -
 					sizebitvec((cache[j].allistrue) ? GETSIGN(datum_l) :
-							   GETSIGN(cache[j].sign));
+							   GETSIGN(cache[j].sign),
+							   siglen);
 		}
 		else
-			size_alpha = hemdistsign(cache[j].sign, GETSIGN(datum_l));
+			size_alpha = hemdistsign(cache[j].sign, GETSIGN(datum_l), siglen);
 
 		if (ISALLTRUE(datum_r) || cache[j].allistrue)
 		{
 			if (ISALLTRUE(datum_r) && cache[j].allistrue)
 				size_beta = 0;
 			else
-				size_beta = SIGLENBIT -
+				size_beta = SIGLENBIT(siglen) -
 					sizebitvec((cache[j].allistrue) ? GETSIGN(datum_r) :
-							   GETSIGN(cache[j].sign));
+							   GETSIGN(cache[j].sign),
+							   siglen);
 		}
 		else
-			size_beta = hemdistsign(cache[j].sign, GETSIGN(datum_r));
+			size_beta = hemdistsign(cache[j].sign, GETSIGN(datum_r), siglen);
 
 		if (size_alpha < size_beta + WISH_F(v->spl_nleft, v->spl_nright, 0.1))
 		{
 			if (ISALLTRUE(datum_l) || cache[j].allistrue)
 			{
 				if (!ISALLTRUE(datum_l))
-					MemSet((void *) GETSIGN(datum_l), 0xff, sizeof(BITVEC));
+					MemSet((void *) GETSIGN(datum_l), 0xff, siglen);
 			}
 			else
 			{
 				ptr = cache[j].sign;
-				LOOPBYTE
+				LOOPBYTE(siglen)
 					union_l[i] |= ptr[i];
 			}
 			*left++ = j;
@@ -918,12 +931,12 @@ gtrgm_picksplit(PG_FUNCTION_ARGS)
 			if (ISALLTRUE(datum_r) || cache[j].allistrue)
 			{
 				if (!ISALLTRUE(datum_r))
-					MemSet((void *) GETSIGN(datum_r), 0xff, sizeof(BITVEC));
+					MemSet((void *) GETSIGN(datum_r), 0xff, siglen);
 			}
 			else
 			{
 				ptr = cache[j].sign;
-				LOOPBYTE
+				LOOPBYTE(siglen)
 					union_r[i] |= ptr[i];
 			}
 			*right++ = j;
@@ -937,3 +950,17 @@ gtrgm_picksplit(PG_FUNCTION_ARGS)
 
 	PG_RETURN_POINTER(v);
 }
+
+Datum
+gtrgm_options(PG_FUNCTION_ARGS)
+{
+	local_relopts *relopts = (local_relopts *) PG_GETARG_POINTER(0);
+
+	init_local_reloptions(relopts, sizeof(TrgmGistOptions));
+	add_local_int_reloption(relopts, "siglen",
+							"signature length in bytes",
+							SIGLEN_DEFAULT, 1, SIGLEN_MAX,
+							offsetof(TrgmGistOptions, siglen));
+
+	PG_RETURN_VOID();
+}