Restructure function-internal caching in the range type code.

Move the responsibility for caching specialized information about range
types into the type cache, so that the catalog lookups only have to occur
once per session.  Rearrange APIs a bit so that fn_extra caching is
actually effective in the GiST support code.  (Use of OidFunctionCallN is
bad enough for performance in itself, but it also prevents the function
from exploiting fn_extra caching.)

The range I/O functions are still not very bright about caching repeated
lookups, but that seems like material for a separate patch.

Also, avoid unnecessary use of memcpy to fetch/store the range type OID and
flags, and don't use the full range_deserialize machinery when all we need
to see is the flags value.

Also fix API error in range_gist_penalty --- it was failing to set *penalty
for any case involving an empty range.

1 files changed, 14 insertions, 0 deletions

diff --git a/src/include/utils/typcache.h b/src/include/utils/typcache.h
index eb93c1d3b54..823b6ae576a 100644
--- a/src/include/utils/typcache.h
+++ b/src/include/utils/typcache.h
@@ -32,6 +32,7 @@ typedef struct TypeCacheEntry
 	int16		typlen;
 	bool		typbyval;
 	char		typalign;
+	char		typstorage;
 	char		typtype;
 	Oid			typrelid;
 
@@ -71,6 +72,18 @@ typedef struct TypeCacheEntry
 	 */
 	TupleDesc	tupDesc;
 
+	/*
+	 * Fields computed when TYPECACHE_RANGE_INFO is requested.  Zeroes if
+	 * not a range type or information hasn't yet been requested.  Note that
+	 * rng_cmp_proc_finfo could be different from the element type's default
+	 * btree comparison function.
+	 */
+	struct TypeCacheEntry *rngelemtype;	/* range's element type */
+	Oid			rng_collation;			/* collation for comparisons, if any */
+	FmgrInfo	rng_cmp_proc_finfo;		/* comparison function */
+	FmgrInfo	rng_canonical_finfo;	/* canonicalization function, if any */
+	FmgrInfo	rng_subdiff_finfo;		/* difference function, if any */
+
 	/* Private data, for internal use of typcache.c only */
 	int			flags;			/* flags about what we've computed */
 
@@ -93,6 +106,7 @@ typedef struct TypeCacheEntry
 #define TYPECACHE_TUPDESC			0x0100
 #define TYPECACHE_BTREE_OPFAMILY	0x0200
 #define TYPECACHE_HASH_OPFAMILY		0x0400
+#define TYPECACHE_RANGE_INFO		0x0800
 
 extern TypeCacheEntry *lookup_type_cache(Oid type_id, int flags);