More sensible character_octet_length

For character types with typmod, character_octet_length columns in the
information schema now show the maximum character length times the
maximum length of a character in the server encoding, instead of some
huge value as before.

doc/src/sgml/information_schema.sgml

@@ -1,4 +1,4 @@
-<!-- $PostgreSQL: pgsql/doc/src/sgml/information_schema.sgml,v 1.39 2009/06/10 07:03:34 petere Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/information_schema.sgml,v 1.40 2009/07/07 18:23:13 petere Exp $ -->
 
 <chapter id="information-schema">
  <title>The Information Schema</title>
@@ -343,10 +343,10 @@
       <entry><type>cardinal_number</type></entry>
       <entry>
        If <literal>data_type</literal> identifies a character type,
-       the maximum possible length in octets (bytes) of a datum (this
+       the maximum possible length in octets (bytes) of a datum; null
-       should not be of concern to
+       for all other data types.  The maximum octet length depends on
-       <productname>PostgreSQL</productname> users); null for all
+       the declared character maximum length (see above) and the
-       other data types.
+       server encoding.
       </entry>
      </row>
 
@@ -947,9 +947,10 @@
       <entry><type>cardinal_number</type></entry>
       <entry>
        If <literal>data_type</literal> identifies a character type,
-       the maximum possible length in octets (bytes) of a datum (this
+       the maximum possible length in octets (bytes) of a datum; null
-       should not be of concern to <productname>PostgreSQL</productname> users); null for all
+       for all other data types.  The maximum octet length depends on
-       other data types.
+       the declared character maximum length (see above) and the
+       server encoding.
       </entry>
      </row>
 
@@ -1688,9 +1689,9 @@
       <entry><type>cardinal_number</type></entry>
       <entry>
        If the domain has a character type, the maximum possible length
-       in octets (bytes) of a datum (this should not be of concern to
+       in octets (bytes) of a datum; null for all other data types.
-       <productname>PostgreSQL</productname> users); null for all
+       The maximum octet length depends on the declared character
-       other data types.
+       maximum length (see above) and the server encoding.
       </entry>
      </row>
 

src/backend/catalog/information_schema.sql

@@ -4,7 +4,7 @@
  *
  * Copyright (c) 2003-2009, PostgreSQL Global Development Group
  *
- * $PostgreSQL: pgsql/src/backend/catalog/information_schema.sql,v 1.54 2009/06/10 07:03:34 petere Exp $
+ * $PostgreSQL: pgsql/src/backend/catalog/information_schema.sql,v 1.55 2009/07/07 18:23:13 petere Exp $
  */
 
 /*
@@ -104,7 +104,10 @@ CREATE FUNCTION _pg_char_octet_length(typid oid, typmod int4) RETURNS integer
     AS
 $$SELECT
   CASE WHEN $1 IN (25, 1042, 1043) /* text, char, varchar */
-       THEN CAST(2^30 AS integer)
+       THEN CASE WHEN $2 = -1 /* default typmod */
+                 THEN CAST(2^30 AS integer)
+                 ELSE information_schema._pg_char_max_length($1, $2) * pg_catalog.pg_encoding_max_length((SELECT encoding FROM pg_database WHERE datname = current_database()))
+            END
        ELSE null
   END$$;
 

src/backend/utils/mb/mbutils.c

@@ -4,7 +4,7 @@
  *
  * Tatsuo Ishii
  *
- * $PostgreSQL: pgsql/src/backend/utils/mb/mbutils.c,v 1.87 2009/06/11 14:49:05 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/mb/mbutils.c,v 1.88 2009/07/07 18:23:14 petere Exp $
  */
 #include "postgres.h"
 
@@ -482,6 +482,17 @@ length_in_encoding(PG_FUNCTION_ARGS)
 
 }
 
+Datum
+pg_encoding_max_length_sql(PG_FUNCTION_ARGS)
+{
+	int encoding = PG_GETARG_INT32(0);
+
+	if (PG_VALID_ENCODING(encoding))
+		return pg_wchar_table[encoding].maxmblen;
+	else
+		PG_RETURN_NULL();
+}
+
 /*
  * convert client encoding to server encoding.
  */

src/include/catalog/catversion.h

@@ -37,7 +37,7 @@
  * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.531 2009/06/11 14:49:09 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/catversion.h,v 1.532 2009/07/07 18:23:14 petere Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	200904091
+#define CATALOG_VERSION_NO	200907071
 
 #endif

src/include/catalog/pg_proc.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.544 2009/06/11 14:49:09 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/pg_proc.h,v 1.545 2009/07/07 18:23:14 petere Exp $
  *
  * NOTES
  *	  The script catalog/genbki.sh reads this file and generates .bki
@@ -2278,6 +2278,9 @@ DESCR("convert encoding name to encoding id");
 DATA(insert OID = 1597 (  pg_encoding_to_char	   PGNSP PGUID 12 1 0 0 f f f t f s 1 0 19 "23" _null_ _null_ _null_ _null_ PG_encoding_to_char _null_ _null_ _null_ ));
 DESCR("convert encoding id to encoding name");
 
+DATA(insert OID = 2319 (  pg_encoding_max_length   PGNSP PGUID 12 1 0 0 f f f t f i 1 0 23 "23" _null_ _null_ _null_ _null_ pg_encoding_max_length_sql _null_ _null_ _null_ ));
+DESCR("maximum octet length of a character in an eocidng");
+
 DATA(insert OID = 1638 (  oidgt				   PGNSP PGUID 12 1 0 0 f f f t f i 2 0 16 "26 26" _null_ _null_ _null_ _null_ oidgt _null_ _null_ _null_ ));
 DESCR("greater-than");
 DATA(insert OID = 1639 (  oidge				   PGNSP PGUID 12 1 0 0 f f f t f i 2 0 16 "26 26" _null_ _null_ _null_ _null_ oidge _null_ _null_ _null_ ));

src/include/utils/builtins.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/utils/builtins.h,v 1.332 2009/03/09 14:34:34 petere Exp $
+ * $PostgreSQL: pgsql/src/include/utils/builtins.h,v 1.333 2009/07/07 18:23:15 petere Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -948,6 +948,7 @@ extern Datum pg_convert(PG_FUNCTION_ARGS);
 extern Datum pg_convert_to(PG_FUNCTION_ARGS);
 extern Datum pg_convert_from(PG_FUNCTION_ARGS);
 extern Datum length_in_encoding(PG_FUNCTION_ARGS);
+extern Datum pg_encoding_max_length_sql(PG_FUNCTION_ARGS);
 
 /* format_type.c */
 extern Datum format_type(PG_FUNCTION_ARGS);