Re: A Replication Idea

From: "Zeugswetter Andreas SB SD" <ZeugswetterA(at)spardat(dot)at>
To: "Orion Henry" <orion(at)trustcommerce(dot)com>, <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: A Replication Idea
Date: 2002-02-22 14:31:49
Message-ID: 46C15C39FEB2C44BA555E356FBCD6FA41EB51C@m0114.s-mxs.net
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> The only assumption I am aware of
> that I am making is that two identical databases, given the same set of
> arbitrary transactions will end up being the same.

Unfortunately I do not think you can make that assumption. Since
response time of the two machines will be different you might end up
generating different data on different servers.

> If an insert/update/delete/DDL command comes, it forwards it to both
> machines.
> If a query comes down the line it forwards it to one machine or the
> other.

Also in PostgreSQL you cannot easily distinguish between read-only
and read-write statements. Not without looking at the query plan.

Thus imho generic replication cannot be achieved by plugging something between
clients and the backend.

Andreas

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