Re: [HACKERS] event triggers with args?

2015-02-25 Thread Fabien COELHO


Hello Andres,


So I have a question: is there a particular reason why arguments were not
provided in the first place?


Yea. The existing trigger argument mechanims is extremely odd
implementation wise - they don't have real datatypes and aren't passed
via the normal parameter passing mechanism.


Indeed, I can only agree!

IIRC we discussed this back when it was introduced and decided against 
introducing for now.


I think the whole trigger argument infrastructure, even for normal 
triggers, should be rewritten. After that we could think of adding it 
for event triggers.


Ok. That sound reasonable. Thanks for the answer.

I think that the new method will have to be upward compatible. This 
suggest providing TG_ARGV with casted to text arguments. Not necessarily a 
big issue.


I've looked into the parser. ISTM that trigger call parameter list could 
use a expr_list, which would have to be evaluated and serialised in 
pg_trigger, maybe as ROW does.


--
Fabien.


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Re: [HACKERS] event triggers with args?

2015-02-25 Thread Andres Freund
On 2015-02-25 10:43:57 +0100, Fabien COELHO wrote:
 
 While looking at event triggers, I noticed that, contrary to basic triggers,
 arguments are not allowed.
 
 However, the example in the documentation with an hour-based filtering of
 ddl commands suggest some handling of arguments would be useful so as to
 allow more generic event triggers.
 
 So I have a question: is there a particular reason why arguments were not
 provided in the first place?

Yea. The existing trigger argument mechanims is extremely odd
implementation wise - they don't have real datatypes and aren't passed
via the normal parameter passing mechanism. IIRC we discussed this back
when it was introduced and decided against introducing for now.

I think the whole trigger argument infrastructure, even for normal
triggers, should be rewritten. After that we could think of adding it
for event triggers.

Greetings,

Andres Freund

-- 
 Andres Freund http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training  Services


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