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, 8 insertions, 9 deletions

diff --git a/contrib/pg_trgm/trgm.h b/contrib/pg_trgm/trgm.h
index 0fd600d5810..0c34b96d808 100644
--- a/contrib/pg_trgm/trgm.h
+++ b/contrib/pg_trgm/trgm.h
@@ -73,17 +73,16 @@ typedef struct
 #define TRGMHDRSIZE		  (VARHDRSZ + sizeof(uint8))
 
 /* gist */
+#define SIGLEN_DEFAULT	(sizeof(int) * 3)
+#define SIGLEN_MAX		GISTMaxIndexKeySize
 #define BITBYTE 8
-#define SIGLENINT  3			/* >122 => key will toast, so very slow!!! */
-#define SIGLEN	( sizeof(int)*SIGLENINT )
 
-#define SIGLENBIT (SIGLEN*BITBYTE - 1)	/* see makesign */
+#define SIGLENBIT(siglen) ((siglen) * BITBYTE - 1)	/* see makesign */
 
-typedef char BITVEC[SIGLEN];
 typedef char *BITVECP;
 
-#define LOOPBYTE \
-			for(i=0;i<SIGLEN;i++)
+#define LOOPBYTE(siglen) \
+			for (i = 0; i < (siglen); i++)
 
 #define GETBYTE(x,i) ( *( (BITVECP)(x) + (int)( (i) / BITBYTE ) ) )
 #define GETBITBYTE(x,i) ( (((char)(x)) >> (i)) & 0x01 )
@@ -91,8 +90,8 @@ typedef char *BITVECP;
 #define SETBIT(x,i)   GETBYTE(x,i) |=  ( 0x01 << ( (i) % BITBYTE ) )
 #define GETBIT(x,i) ( (GETBYTE(x,i) >> ( (i) % BITBYTE )) & 0x01 )
 
-#define HASHVAL(val) (((unsigned int)(val)) % SIGLENBIT)
-#define HASH(sign, val) SETBIT((sign), HASHVAL(val))
+#define HASHVAL(val, siglen) (((unsigned int)(val)) % SIGLENBIT(siglen))
+#define HASH(sign, val, siglen) SETBIT((sign), HASHVAL(val, siglen))
 
 #define ARRKEY			0x01
 #define SIGNKEY			0x02
@@ -102,7 +101,7 @@ typedef char *BITVECP;
 #define ISSIGNKEY(x)	( ((TRGM*)x)->flag & SIGNKEY )
 #define ISALLTRUE(x)	( ((TRGM*)x)->flag & ALLISTRUE )
 
-#define CALCGTSIZE(flag, len) ( TRGMHDRSIZE + ( ( (flag) & ARRKEY ) ? ((len)*sizeof(trgm)) : (((flag) & ALLISTRUE) ? 0 : SIGLEN) ) )
+#define CALCGTSIZE(flag, len) ( TRGMHDRSIZE + ( ( (flag) & ARRKEY ) ? ((len)*sizeof(trgm)) : (((flag) & ALLISTRUE) ? 0 : (len)) ) )
 #define GETSIGN(x)		( (BITVECP)( (char*)x+TRGMHDRSIZE ) )
 #define GETARR(x)		( (trgm*)( (char*)x+TRGMHDRSIZE ) )
 #define ARRNELEM(x) ( ( VARSIZE(x) - TRGMHDRSIZE )/sizeof(trgm) )