From fc3649fd4c4b1571103f141bd804406e95e449b5 Mon Sep 17 00:00:00 2001
From: Tom Lane
Date: Tue, 25 Aug 2015 19:11:17 -0400
Subject: Docs: be explicit about datatype matching for lead/lag functions.
The default argument, if given, has to be of exactly the same datatype
as the first argument; but this was not stated in so many words, and
the error message you get about it might not lead your thought in the
right direction. Per bug #13587 from Robert McGehee.
A quick scan says that these are the only two built-in functions with two
anyelement arguments and no other polymorphic arguments. There are plenty
of cases of, eg, anyarray and anyelement, but those seem less likely to
confuse. For instance this doesn't seem terribly hard to figure out:
"function array_remove(integer[], numeric) does not exist". So I've
contented myself with fixing these two cases.
---
doc/src/sgml/func.sgml | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)
(limited to 'doc/src')
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 730ac35b48b..1ea9e58f54e 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -13216,9 +13216,9 @@ SELECT xmlagg(x) FROM (SELECT x FROM test ORDER BY y DESC) AS tab;
lag
- lag(value any
+ lag(value anyelement
[, offset integer
- [, default any ]])
+ [, default anyelement ]])
@@ -13228,7 +13228,9 @@ SELECT xmlagg(x) FROM (SELECT x FROM test ORDER BY y DESC) AS tab;
returns value evaluated at
the row that is offset
rows before the current row within the partition; if there is no such
- row, instead return default.
+ row, instead return default
+ (which must be of the same type as
+ value).
Both offset and
default are evaluated
with respect to the current row. If omitted,
@@ -13243,9 +13245,9 @@ SELECT xmlagg(x) FROM (SELECT x FROM test ORDER BY y DESC) AS tab;
lead
- lead(value any
+ lead(value anyelement
[, offset integer
- [, default any ]])
+ [, default anyelement ]])
@@ -13255,7 +13257,9 @@ SELECT xmlagg(x) FROM (SELECT x FROM test ORDER BY y DESC) AS tab;
returns value evaluated at
the row that is offset
rows after the current row within the partition; if there is no such
- row, instead return default.
+ row, instead return default
+ (which must be of the same type as
+ value).
Both offset and
default are evaluated
with respect to the current row. If omitted,
--
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