Message-ID: <44D8D9DE.50000@lsd.di.uminho.pt>
Date: Tue, 08 Aug 2006 19:37:18 +0100
From: alfranio correia junior <alfranio@lsd.di.uminho.pt>
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To: Markus Schiltknecht <markus@bluegap.ch>
CC: Christopher Browne <cbbrowne@acm.org>,  pgsql-hackers@postgresql.org
Subject: Re: standard interfaces for replication providers
References: <44D30B31.2070403@lsd.di.uminho.pt>
	<200608041733.24228.jop@lsd.di.uminho.pt>
	<44D70EDA.9060602@bluegap.ch>
	<200608071940.26750.jop@lsd.di.uminho.pt>
	<44D89EA5.5090703@bluegap.ch> <87irl3uqgx.fsf@wolfe.cbbrowne.com>
	<44D8D334.5050808@bluegap.ch>
In-Reply-To: <44D8D334.5050808@bluegap.ch>
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Markus Schiltknecht wrote:
>
> I'm questioning if a replication system can be written by only using
> triggers as hooks. AFAIK Slony-I uses triggers, so you can probably
> better comment on problems or limitations using triggers. For me a
> shared library with some hooks as C function calls seems a more
> plausible approach.
Of course not...
It is impossible to build a replication system entirely by only using
triggers...
But definitely, there is a set of common requirements among a variety of
replication systems. Moreover, such requirements are also useful to
other systems as well.

Roughly, the GAPI reflects any event inside a database system and allows
any application to intercept and modify them.
For instance, an event might be:
    1 -  database shutdown, startup
    2 - connection shutdown, startup
    3 - statement reception
    4 - parsing
    5 - execution plan generation
    6 - tuples written


Our current prototype covers some of them and some of them partially (2,6).
Besides, we also need the priority mechanism.


Best regards,

Alfranio Junior.