diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/typeconv.sgml | 27 |
1 files changed, 22 insertions, 5 deletions
diff --git a/doc/src/sgml/typeconv.sgml b/doc/src/sgml/typeconv.sgml index c5373aa7533..7cf3efdb1ae 100644 --- a/doc/src/sgml/typeconv.sgml +++ b/doc/src/sgml/typeconv.sgml @@ -1,4 +1,4 @@ -<!-- $PostgreSQL: pgsql/doc/src/sgml/typeconv.sgml,v 1.52 2007/06/05 21:31:04 tgl Exp $ --> +<!-- $PostgreSQL: pgsql/doc/src/sgml/typeconv.sgml,v 1.53 2007/11/26 16:46:50 tgl Exp $ --> <chapter Id="typeconv"> <title>Type Conversion</title> @@ -845,9 +845,17 @@ and Related Constructs</title> <step performance="required"> <para> +If all inputs are of the same type, and it is not <type>unknown</type>, +resolve as that type. Otherwise, replace any domain types in the list with +their underlying base types. +</para> +</step> + +<step performance="required"> +<para> If all inputs are of type <type>unknown</type>, resolve as type <type>text</type> (the preferred type of the string category). -Otherwise, ignore the <type>unknown</type> inputs while choosing the result type. +Otherwise, the <type>unknown</type> inputs will be ignored. </para> </step> @@ -860,14 +868,23 @@ If the non-unknown inputs are not all of the same type category, fail. <step performance="required"> <para> Choose the first non-unknown input type which is a preferred type in -that category or allows all the non-unknown inputs to be implicitly -converted to it. +that category, if there is one. +</para> +</step> + +<step performance="required"> +<para> +Otherwise, choose the last non-unknown input type that allows all the +preceding non-unknown inputs to be implicitly converted to it. (There +always is such a type, since at least the first type in the list must +satisfy this condition.) </para> </step> <step performance="required"> <para> -Convert all inputs to the selected type. +Convert all inputs to the selected type. Fail if there is not a +conversion from a given input to the selected type. </para> </step> </procedure> |