Fix default signature length for gist_ltree_ops

911e702 implemented operator class parameters including the signature length
in ltree.  Previously, the signature length for gist_ltree_ops was 8.  Because
of bug 911e702 the default signature length for gist_ltree_ops became 28 for
ltree 1.1 (where options method is NOT provided) and 8 for ltree 1.2 (where
options method is provided).  This commit changes the default signature length
for ltree 1.1 to 8.

Existing gist_ltree_ops indexes might be corrupted in various scenarios.
Thus, we have to recommend reindexing all the gist_ltree_ops indexes after
the upgrade.

Reported-by: Victor Yegorov
Reviewed-by: Tomas Vondra, Tom Lane, Andres Freund, Nikita Glukhov
Reviewed-by: Andrew Dunstan
Author: Tomas Vondra, Alexander Korotkov
Discussion: https://postgr.es/m/17406-71e02820ae79bb40%40postgresql.org
Discussion: https://postgr.es/m/d80e0a55-6c3e-5b26-53e3-3c4f973f737c%40enterprisedb.com

Author: akorotkov

contrib/ltree/ltree.h

@@ -229,11 +229,13 @@ int			ltree_strncasecmp(const char *a, const char *b, size_t s);
 
 /* GiST support for ltree */
 
-#define SIGLEN_MAX		GISTMaxIndexKeySize
-#define SIGLEN_DEFAULT	(2 * sizeof(int32))
 #define BITBYTE 8
-#define SIGLEN	(sizeof(int32) * SIGLENINT)
 #define SIGLENBIT(siglen) ((siglen) * BITBYTE)
+#define LTREE_SIGLEN_DEFAULT	(2 * sizeof(int32))
+#define LTREE_SIGLEN_MAX		GISTMaxIndexKeySize
+#define LTREE_GET_SIGLEN()		(PG_HAS_OPCLASS_OPTIONS() ? \
+								 ((LtreeGistOptions *) PG_GET_OPCLASS_OPTIONS())->siglen : \
+								 LTREE_SIGLEN_DEFAULT)
 
 typedef unsigned char *BITVECP;
 

contrib/ltree/ltree_gist.c

@@ -130,7 +130,7 @@ ltree_same(PG_FUNCTION_ARGS)
 	ltree_gist *a = (ltree_gist *) PG_GETARG_POINTER(0);
 	ltree_gist *b = (ltree_gist *) PG_GETARG_POINTER(1);
 	bool	   *result = (bool *) PG_GETARG_POINTER(2);
-	int			siglen = LTREE_GET_ASIGLEN();
+	int			siglen = LTREE_GET_SIGLEN();
 
 	*result = false;
 	if (LTG_ISONENODE(a) != LTG_ISONENODE(b))
@@ -190,7 +190,7 @@ ltree_union(PG_FUNCTION_ARGS)
 {
 	GistEntryVector *entryvec = (GistEntryVector *) PG_GETARG_POINTER(0);
 	int		   *size = (int *) PG_GETARG_POINTER(1);
-	int			siglen = LTREE_GET_ASIGLEN();
+	int			siglen = LTREE_GET_SIGLEN();
 	BITVECP		base = palloc0(siglen);
 	int32		i,
 				j;
@@ -260,7 +260,7 @@ ltree_penalty(PG_FUNCTION_ARGS)
 	ltree_gist *origval = (ltree_gist *) DatumGetPointer(((GISTENTRY *) PG_GETARG_POINTER(0))->key);
 	ltree_gist *newval = (ltree_gist *) DatumGetPointer(((GISTENTRY *) PG_GETARG_POINTER(1))->key);
 	float	   *penalty = (float *) PG_GETARG_POINTER(2);
-	int			siglen = LTREE_GET_ASIGLEN();
+	int			siglen = LTREE_GET_SIGLEN();
 	int32		cmpr,
 				cmpl;
 
@@ -292,7 +292,7 @@ ltree_picksplit(PG_FUNCTION_ARGS)
 {
 	GistEntryVector *entryvec = (GistEntryVector *) PG_GETARG_POINTER(0);
 	GIST_SPLITVEC *v = (GIST_SPLITVEC *) PG_GETARG_POINTER(1);
-	int			siglen = LTREE_GET_ASIGLEN();
+	int			siglen = LTREE_GET_SIGLEN();
 	OffsetNumber j;
 	int32		i;
 	RIX		   *array;
@@ -618,7 +618,7 @@ ltree_consistent(PG_FUNCTION_ARGS)
 
 	/* Oid		subtype = PG_GETARG_OID(3); */
 	bool	   *recheck = (bool *) PG_GETARG_POINTER(4);
-	int			siglen = LTREE_GET_ASIGLEN();
+	int			siglen = LTREE_GET_SIGLEN();
 	ltree_gist *key = (ltree_gist *) DatumGetPointer(entry->key);
 	void	   *query = NULL;
 	bool		res = false;
@@ -724,7 +724,7 @@ ltree_gist_options(PG_FUNCTION_ARGS)
 	init_local_reloptions(relopts, sizeof(LtreeGistOptions));
 	add_local_int_reloption(relopts, "siglen",
 							"signature length in bytes",
-							SIGLEN_DEFAULT, 1, SIGLEN_MAX,
+							LTREE_SIGLEN_DEFAULT, 1, LTREE_SIGLEN_MAX,
 							offsetof(LtreeGistOptions, siglen));
 
 	PG_RETURN_VOID();