Re: A Replication Idea - Mailing list pgsql-hackers

From Zeugswetter Andreas SB SD
Subject Re: A Replication Idea
Date
Msg-id 46C15C39FEB2C44BA555E356FBCD6FA41EB51C@m0114.s-mxs.net
Whole thread Raw
In response to A Replication Idea  (Orion Henry <orion@trustcommerce.com>)
List pgsql-hackers
> 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


pgsql-hackers by date:

Previous
From: Ola Sundell
Date:
Subject: Re: how to stop running postgres process
Next
From: Tom Lane
Date:
Subject: Re: point in time recovery and moving datafiles online