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Re: Command Triggers, patch v11

From: Thom Brown <thom(at)linux(dot)com>
To: Dimitri Fontaine <dimitri(at)2ndquadrant(dot)fr>
Cc: PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Command Triggers, patch v11
Date: 2012-02-25 16:36:41
Message-ID: CAA-aLv7G0WLrQ3fgZ76DybrEmgGriJ-+otgsf6TyOrEcJfWcFw@mail.gmail.com (view raw or flat)
Thread:
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On 25 February 2012 14:30, Thom Brown <thom(at)linux(dot)com> wrote:
> On 25 February 2012 13:28, Thom Brown <thom(at)linux(dot)com> wrote:
>> On 25 February 2012 13:15, Thom Brown <thom(at)linux(dot)com> wrote:
>>> On 25 February 2012 12:42, Thom Brown <thom(at)linux(dot)com> wrote:
>>>> On 25 February 2012 12:07, Thom Brown <thom(at)linux(dot)com> wrote:
>>>>> On 25 February 2012 12:00, Dimitri Fontaine <dimitri(at)2ndquadrant(dot)fr> wrote:
>>>>>
>>>>> D'oh, just as I sent some more queries...
>>>>>
>>>>>> Thom Brown <thom(at)linux(dot)com> writes:
>>>>>>> Is there any reason why the list of commands that command triggers can
>>>>>>> be used with isn't in alphabetical order?  Also it appears to show
>>>>>>
>>>>>> Any reason why?  I don't suppose it's really important one way or the
>>>>>> other, so I'm waiting on some more voices before working on it.
>>>>>
>>>>> Just so it's easy to scan.  If someone is looking for CREATE CAST,
>>>>> they'd kind of expect it near the drop of the CREATE list, but it's
>>>>> actually toward the bottom.  It just looks random at the moment.
>>>>>
>>>>>>> The ALTER COMMAND TRIGGER page also doesn't show which commands it can
>>>>>>> be used against.  Perhaps, rather than repeat the list, there could be
>>>>>>> a note to say that a list of valid commands can be found on the CREATE
>>>>>>> COMMAND TRIGGER page?
>>>>>>
>>>>>> Well you can only alter a command that you were successful in creating,
>>>>>> right?  So I'm not sure that's needed here.  By that count though, I
>>>>>> maybe should remove the supported command list from DROP COMMAND TRIGGER
>>>>>> reference page?
>>>>>
>>>>> Sure, that would be more consistent.  You're right, it's not needed.
>>>>> It just seemed odd that one of the statements lacked what both others
>>>>> had.
>>>>
>>>> Yet another comment... (I should have really started looking at this
>>>> at an earlier stage)
>>>>
>>>> It seems that if one were to enforce a naming convention for relations
>>>> as shown in the 2nd example for CREATE COMMAND TRIGGER, it could be
>>>> circumvented by someone using CREATE TABLE name AS...
>>>>
>>>> test=# CREATE TABLE badname (id int, a int, b text);
>>>> ERROR:  invalid relation name: badname
>>>> test=# CREATE TABLE badname AS SELECT 1::int id, 1::int a, ''::text b;
>>>> SELECT 1
>>>>
>>>> This doesn't even get picked up by ANY COMMAND.
>>>
>>> CREATE COMMAND TRIGGER doesn't output in pg_dump or pg_dumpall.  I'd
>>> expect ALTER COMMAND TRIGGER to output too for when individual
>>> commands are disabled etc.
>>
>> Just found another case where a table can be created without a command
>> trigger firing:
>>
>> SELECT * INTO badname FROM goodname;
>
> Right, hopefully this should be my last piece of list spam for the
> time being. (apologies, I thought I'd just try it out at first, but
> it's ended up being reviewed piecemeal)

I was wrong.. a couple of corrections to my own response:

> On CREATE COMMAND TRIGGER page:
>
> “The trigger will be associated with the specified command and will
> execute the specified function function_name when that command is
> run.”
> should be:
> “The trigger will be associated with the specified commands and will
> execute the specified function function_name when those commands are
> run.”

Actually, perhaps "...when any of those commands..."

> On ALTER COMMAND TRIGGER page:
>
> “ALTER COMMAND TRIGGER name ON command SET enabled”
> should be:
> “ALTER COMMAND TRIGGER name ON command [, ... ] SET enabled”

This one is nonsense, so please ignore it.

-- 
Thom

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