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Commitf27976c

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Make length() disregard trailing spaces in char(n) values, per discussion
some time ago and recent patch from Gavin Sherry. Update documentationto point out that trailing spaces are insignificant in char(n).
1 parent08b0e60 commitf27976c

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2 files changed

+27
-9
lines changed

2 files changed

+27
-9
lines changed

‎doc/src/sgml/datatype.sgml

Lines changed: 18 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
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<!--
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$PostgreSQL: pgsql/doc/src/sgml/datatype.sgml,v 1.140 2004/01/20 22:46:06 tgl Exp $
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$PostgreSQL: pgsql/doc/src/sgml/datatype.sgml,v 1.141 2004/02/01 06:27:48 tgl Exp $
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-->
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<chapter id="datatype">
@@ -901,6 +901,18 @@ CREATE TABLE <replaceable class="parameter">tablename</replaceable> (
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management systems have it as well.
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</para>
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<para>
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Values of type <type>character</type> are physically padded
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with spaces to the specified width <replaceable>n</>, and are
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stored and displayed that way. However, the padding spaces are
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treated as semantically insignificant. Trailing spaces are
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disregarded when comparing two values of type <type>character</type>,
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and they will be removed when converting a <type>character</type> value
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to one of the other string types. Note that trailing spaces
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<emphasis>are</> semantically significant in
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<type>character varying</type> and <type>text</type> values.
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</para>
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<para>
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The storage requirement for data of these types is 4 bytes plus the
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actual string, and in case of <type>character</type> plus the
@@ -922,7 +934,11 @@ CREATE TABLE <replaceable class="parameter">tablename</replaceable> (
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<para>
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There are no performance differences between these three types,
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apart from the increased storage size when using the blank-padded
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type.
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type. While <type>character(<replaceable>n</>)</type> has performance
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advantages in some other database systems, it has no such advantages in
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<productname>PostgreSQL</productname>. In most situations
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<type>text</type> or <type>character varying</type> should be used
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instead.
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</para>
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</tip>
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‎src/backend/utils/adt/varchar.c

Lines changed: 9 additions & 7 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/utils/adt/varchar.c,v 1.103 2003/11/29 19:51:59 pgsql Exp $
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* $PostgreSQL: pgsql/src/backend/utils/adt/varchar.c,v 1.104 2004/02/01 06:27:48 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
@@ -510,14 +510,16 @@ Datum
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bpcharlen(PG_FUNCTION_ARGS)
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{
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BpChar*arg=PG_GETARG_BPCHAR_P(0);
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intlen;
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/* optimization for single byte encoding */
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if (pg_database_encoding_max_length() <=1)
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PG_RETURN_INT32(VARSIZE(arg)-VARHDRSZ);
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/* get number of bytes, ignoring trailing spaces */
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len=bcTruelen(arg);
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/* in multibyte encoding, convert to number of characters */
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if (pg_database_encoding_max_length()!=1)
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len=pg_mbstrlen_with_len(VARDATA(arg),len);
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PG_RETURN_INT32(
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pg_mbstrlen_with_len(VARDATA(arg),VARSIZE(arg)-VARHDRSZ)
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);
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PG_RETURN_INT32(len);
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}
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Datum

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