From: | Darko Prenosil <darko(dot)prenosil(at)finteh(dot)hr> |
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To: | Nagib Abi Fadel <nagib_postgres(at)yahoo(dot)com>, pgsql-general(at)postgresql(dot)org |
Cc: | Richard Huxton <dev(at)archonet(dot)com> |
Subject: | Re: Accessing 2 different databases in the same query ? |
Date: | 2003-06-02 12:20:36 |
Message-ID: | 200306021420.36955.darko.prenosil@finteh.hr |
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Lists: | pgsql-general |
On Monday 02 June 2003 10:39, Nagib Abi Fadel wrote:
> From what i read dblink let's us access another database in the same query
> ... Which is great. But does it slow down the query ??
What do You mean slow down ? In compare to what ?
If You question was is such query slower than the query on tables in local
database, the answer is YES. Let me describe the mechanism of dblink:
Your backend process becomes client of another backend (on same or different
server). dblink establishes connection to remote database, executes the
query, and send data to Your backend.
I use dblink over slow ISDN connection, so You can figure out how slow it can
be, but that is the beauty of dblink: You can query servers that are anywhere
on the network !
> And what about making references between tables (creating foreign keys) is
> it possible ?????
>
No, but you can create "remote view" using dblink and then do the same thing
using triggers(foreign keys are just specific triggers).
There are few samples in dblink documentation - check them out !
Regards !
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