diff options
| author | Tom Lane <tgl@sss.pgh.pa.us> | 2020-11-04 15:08:37 -0500 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2020-11-04 15:08:37 -0500 |
| commit | 5c292e6b90433c760a3e15027646c7b94afd0cdd (patch) | |
| tree | f7a22ff756c6234eb7c234aab6d4d60253847767 /doc/src | |
| parent | 40c24bfef92530bd846e111c1742c2a54441c62c (diff) | |
| download | postgresql-5c292e6b90433c760a3e15027646c7b94afd0cdd.tar.gz postgresql-5c292e6b90433c760a3e15027646c7b94afd0cdd.zip | |
Declare lead() and lag() using anycompatible not anyelement.
This allows use of a "default" expression that doesn't slavishly
match the data column's type. Formerly you got something like
"function lag(numeric, integer, integer) does not exist", which
is not just unhelpful but actively misleading.
The SQL spec suggests that the default should be coerced to the data
column's type, but this implementation instead chooses the common
supertype, which seems at least as reasonable.
(Note: I took the opportunity to run "make reformat-dat-files" on
pg_proc.dat, so this commit includes some cosmetic changes to
recently-added entries that aren't related to lead/lag.)
Vik Fearing
Discussion: https://postgr.es/m/77675130-89da-dab1-51dd-492c93dcf5d1@postgresfriends.org
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/func.sgml | 16 |
1 files changed, 8 insertions, 8 deletions
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml index 87a6ba8d10f..46d6db3cfe0 100644 --- a/doc/src/sgml/func.sgml +++ b/doc/src/sgml/func.sgml @@ -19594,17 +19594,17 @@ SELECT count(*) FROM sometable; <indexterm> <primary>lag</primary> </indexterm> - <function>lag</function> ( <parameter>value</parameter> <type>anyelement</type> + <function>lag</function> ( <parameter>value</parameter> <type>anycompatible</type> <optional>, <parameter>offset</parameter> <type>integer</type> - <optional>, <parameter>default</parameter> <type>anyelement</type> </optional></optional> ) - <returnvalue>anyelement</returnvalue> + <optional>, <parameter>default</parameter> <type>anycompatible</type> </optional></optional> ) + <returnvalue>anycompatible</returnvalue> </para> <para> Returns <parameter>value</parameter> evaluated at the row that is <parameter>offset</parameter> rows before the current row within the partition; if there is no such row, instead returns <parameter>default</parameter> - (which must be of the same type as + (which must be of a type compatible with <parameter>value</parameter>). Both <parameter>offset</parameter> and <parameter>default</parameter> are evaluated @@ -19619,17 +19619,17 @@ SELECT count(*) FROM sometable; <indexterm> <primary>lead</primary> </indexterm> - <function>lead</function> ( <parameter>value</parameter> <type>anyelement</type> + <function>lead</function> ( <parameter>value</parameter> <type>anycompatible</type> <optional>, <parameter>offset</parameter> <type>integer</type> - <optional>, <parameter>default</parameter> <type>anyelement</type> </optional></optional> ) - <returnvalue>anyelement</returnvalue> + <optional>, <parameter>default</parameter> <type>anycompatible</type> </optional></optional> ) + <returnvalue>anycompatible</returnvalue> </para> <para> Returns <parameter>value</parameter> evaluated at the row that is <parameter>offset</parameter> rows after the current row within the partition; if there is no such row, instead returns <parameter>default</parameter> - (which must be of the same type as + (which must be of a type compatible with <parameter>value</parameter>). Both <parameter>offset</parameter> and <parameter>default</parameter> are evaluated |