diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/datatype.sgml | 20 |
1 files changed, 18 insertions, 2 deletions
diff --git a/doc/src/sgml/datatype.sgml b/doc/src/sgml/datatype.sgml index 7bbe676a9a1..bcfe1690588 100644 --- a/doc/src/sgml/datatype.sgml +++ b/doc/src/sgml/datatype.sgml @@ -1,5 +1,5 @@ <!-- -$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"> @@ -902,6 +902,18 @@ CREATE TABLE <replaceable class="parameter">tablename</replaceable> ( </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 @@ -922,7 +934,11 @@ CREATE TABLE <replaceable class="parameter">tablename</replaceable> ( <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> |