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Message-ID: <407fa4640807080620r33a3463fgff195d8ae5ef708e@mail.gmail.com>
Date: Tue, 8 Jul 2008 14:20:58 +0100
From: "Michael Nacos" <m.nacos@gmail.com>
To: pgsql-admin@postgresql.org
Subject: Re: How do i compare 2 postgresql instanses ?
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Hello there. Simple counts can certainly prove two databases are not the
same version. But what if you actually want to look at the data? I have been
thinking about row checksums, would you say this would be a reasonable way
of verifying two databases are equivalent? I have many other things on my
mind, so I haven't tried implementing this yet.

Michael


> you could write a little program (awk) to produce an sql file of the form:
> select count(*) from airlines;
> select count(*) from airports;
> select count(*) from airticket;
> select count(*) from airticketflights;
> ....
> select count(*) from zzzobjects;
>
> and then run it against the two databases, and diff the outputs.
> If the outputs are not identical then you have 2 different databases,
> otherwise you have to search more to know the answer.
> So this technique can prove that yours DBs are *not* identical, but does
> not say anything
> about the opposite.
>
> --
> Achilleas Mantzios
>
>

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Hello there. Simple counts can certainly prove two databases are not the same version. But what if you actually want to look at the data? I have been thinking about row checksums, would you say this would be a reasonable way of verifying two databases are equivalent? I have many other things on my mind, so I haven&#39;t tried implementing this yet.<br>
<br>Michael<br><br><div class="gmail_quote"><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><div><div class="Wj3C7c"><br>
</div></div>you could write a little program (awk) to produce an sql file of the form:<br>
select count(*) from airlines;<br>
select count(*) from airports;<br>
select count(*) from airticket;<br>
select count(*) from airticketflights;<br>
....<br>
select count(*) from zzzobjects;<br>
<br>
and then run it against the two databases, and diff the outputs.<br>
If the outputs are not identical then you have 2 different databases,<br>
otherwise you have to search more to know the answer.<br>
So this technique can prove that yours DBs are *not* identical, but does not say anything<br>
about the opposite.<br>
<br>
--<br>
Achilleas Mantzios<br>
<font color="#888888"><br></font></blockquote></div><br>

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