<!--
-$PostgreSQL: pgsql/doc/src/sgml/datatype.sgml,v 1.140 2004/01/20 22:46:06 tgl Exp $
+$PostgreSQL: pgsql/doc/src/sgml/datatype.sgml,v 1.141 2004/02/01 06:27:48 tgl Exp $
-->
<chapter id="datatype">
</para>
<para>
+ Values of type <type>character</type> are physically padded
+ with spaces to the specified width <replaceable>n</>, and are
+ stored and displayed that way. However, the padding spaces are
+ treated as semantically insignificant. Trailing spaces are
+ disregarded when comparing two values of type <type>character</type>,
+ and they will be removed when converting a <type>character</type> value
+ to one of the other string types. Note that trailing spaces
+ <emphasis>are</> semantically significant in
+ <type>character varying</type> and <type>text</type> values.
+ </para>
+
+ <para>
The storage requirement for data of these types is 4 bytes plus the
actual string, and in case of <type>character</type> plus the
padding. Long strings are compressed by the system automatically, so
<para>
There are no performance differences between these three types,
apart from the increased storage size when using the blank-padded
- type.
+ type. While <type>character(<replaceable>n</>)</type> has performance
+ advantages in some other database systems, it has no such advantages in
+ <productname>PostgreSQL</productname>. In most situations
+ <type>text</type> or <type>character varying</type> should be used
+ instead.
</para>
</tip>
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/utils/adt/varchar.c,v 1.103 2003/11/29 19:51:59 pgsql Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/adt/varchar.c,v 1.104 2004/02/01 06:27:48 tgl Exp $
*
*-------------------------------------------------------------------------
*/
bpcharlen(PG_FUNCTION_ARGS)
{
BpChar *arg = PG_GETARG_BPCHAR_P(0);
+ int len;
- /* optimization for single byte encoding */
- if (pg_database_encoding_max_length() <= 1)
- PG_RETURN_INT32(VARSIZE(arg) - VARHDRSZ);
+ /* get number of bytes, ignoring trailing spaces */
+ len = bcTruelen(arg);
+
+ /* in multibyte encoding, convert to number of characters */
+ if (pg_database_encoding_max_length() != 1)
+ len = pg_mbstrlen_with_len(VARDATA(arg), len);
- PG_RETURN_INT32(
- pg_mbstrlen_with_len(VARDATA(arg), VARSIZE(arg) - VARHDRSZ)
- );
+ PG_RETURN_INT32(len);
}
Datum