postgresql/doc
Tom Lane 59029b6fb7 Update docs & tests to reflect that unassigned OLD/NEW are now NULL.
For a long time, plpgsql has allowed trigger functions to parse
references to OLD and NEW even if the current trigger event type didn't
assign a value to one or the other variable; but actually executing such
a reference would fail.  The v11 changes to use "expanded records" for
DTYPE_REC variables changed the behavior so that the unassigned variable
now reads as a null composite value.  While this behavioral change was
more or less unintentional, it seems that leaving it like this is better
than adding code and complexity to be bug-compatible with the old way.
The change doesn't break any code that worked before, and it eliminates
a gotcha that often required extra code to work around.

Hence, update the docs to say that these variables are "null" not
"unassigned" when not relevant to the event type.  And add a regression
test covering the behavior, so that we'll notice if we ever break it
again.

Per report from Kristjan Tammekivi.

Discussion: https://postgr.es/m/CAABK7uL-uC9ZxKBXzo_68pKt7cECfNRv+c35CXZpjq6jCAzYYA@mail.gmail.com
2019-01-09 11:35:14 -05:00
..
src Update docs & tests to reflect that unassigned OLD/NEW are now NULL. 2019-01-09 11:35:14 -05:00
KNOWN_BUGS Remove extra newlines at end and beginning of files, add missing newlines 2010-08-19 05:57:36 +00:00
MISSING_FEATURES Remove extra newlines at end and beginning of files, add missing newlines 2010-08-19 05:57:36 +00:00
Makefile Remove maintainer-check target, fold into normal build 2013-10-10 20:11:56 -04:00
TODO Change documentation references to PG website to use https: not http: 2017-05-20 21:50:47 -04:00
bug.template Stamp HEAD as 12devel 2018-06-30 12:47:59 -04:00