| From: | Laurenz Albe <laurenz(dot)albe(at)cybertec(dot)at> |
|---|---|
| To: | Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk>, Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com> |
| Cc: | pgsql-hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: Fix optimization of foreign-key on update actions |
| Date: | 2019-02-06 09:11:13 |
| Message-ID: | f00b53febc524ce74a2365f2f11d25603e761c84.camel@cybertec.at |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
Andrew Gierth wrote:
> SQL2016, 15.17 Execution of referential actions
>
> 10) If a non-null value of a referenced column RC in the referenced
> table is updated to a value that is distinct from the current value
> of RC, then,
>
> [snip all the stuff about how ON UPDATE actions work]
>
> does that "is distinct from" mean that IS DISTINCT FROM would be true,
> or does it mean "is in some way distinguishable from"? Nothing I can see
> in the spec suggests the latter.
My 2003 standard defines, and even condescends to be informal:
3.1.6.8 distinct (of a pair of comparable values): Capable of being distinguished within a given context.
Informally, not equal, not both null. A null value and a non-null value are distinct.
Yours,
Laurenz Albe
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Andres Freund | 2019-02-06 09:17:40 | Re: fast defaults in heap_getattr vs heap_deform_tuple |
| Previous Message | Bruce Momjian | 2019-02-06 09:00:24 | Re: Early WIP/PoC for inlining CTEs |