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author | Tom Lane <tgl@sss.pgh.pa.us> | 2008-11-13 23:01:09 +0000 |
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committer | Tom Lane <tgl@sss.pgh.pa.us> | 2008-11-13 23:01:09 +0000 |
commit | c23b6fa7b5a338df5d8198a98dd164b475b307d0 (patch) | |
tree | a2b7009e7da54e13192024be828ac532512431c4 /doc/src | |
parent | 312d51798ffb7060b672e1f3b0039639eefffdb4 (diff) | |
download | postgresql-c23b6fa7b5a338df5d8198a98dd164b475b307d0.tar.gz postgresql-c23b6fa7b5a338df5d8198a98dd164b475b307d0.zip |
Marginal editorial improvements for array_agg patch documentation.
Diffstat (limited to 'doc/src')
-rw-r--r-- | doc/src/sgml/func.sgml | 22 |
1 files changed, 11 insertions, 11 deletions
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml index 20443f2b288..aee74366b01 100644 --- a/doc/src/sgml/func.sgml +++ b/doc/src/sgml/func.sgml @@ -1,4 +1,4 @@ -<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.458 2008/11/13 15:59:50 petere Exp $ --> +<!-- $PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.459 2008/11/13 23:01:09 tgl Exp $ --> <chapter id="functions"> <title>Functions and Operators</title> @@ -8387,8 +8387,8 @@ SELECT xmlagg(x) FROM test; </para> <para> - The influence the order of the concatenation, something like the - following approach to sort the input values can be used: + To determine the order of the concatenation, something like the + following approach can be used: <screen><![CDATA[ SELECT xmlagg(x) FROM (SELECT * FROM test ORDER BY y DESC) AS tab; @@ -9772,19 +9772,19 @@ SELECT count(*) FROM sometable; and <function>xmlagg</function>, as well as similar user-defined aggregate functions, produce meaningfully different result values depending on the order of the input values. In the current - implementation, the order of the concatenation is in principle - undefined. Making the input values to be sorted in some other way + implementation, the order of the input is in principle unspecified. + Supplying the input values from a sorted subquery will usually work, however. For example: <screen><![CDATA[ -SELECT xmlagg(x) FROM (SELECT * FROM test ORDER BY y DESC) AS tab; +SELECT xmlagg(x) FROM (SELECT x FROM test ORDER BY y DESC) AS tab; ]]></screen> - But this approach is not guaranteed to work in all situations, and - it is not strictly SQL-conforming. A future version of PostgreSQL - might provide an additional feature to control the order in a - better-defined way (<literal>xmlagg(expr ORDER BY expr, expr, - ...</literal>). + But this syntax is not allowed in the SQL standard, and is + not portable to other database systems. A future version of + <productname>PostgreSQL</> might provide an additional feature to control + the order in a better-defined way (<literal>xmlagg(expr ORDER BY expr, expr, + ...)</literal>). </para> <para> |