Thread: Why aren't master and slave DBs binary identical?

Hackers,

We've noticed that checksums and file sizes for the master database, and
slave database, even after all transactions have been cleared, are not
identical.  Why is that?

--                                  -- Josh Berkus                                    PostgreSQL Experts Inc.
                        http://www.pgexperts.com
 

Hi,

On Friday 18 June 2010 00:22:00 Josh Berkus wrote:
> We've noticed that checksums and file sizes for the master database, and
> slave database, even after all transactions have been cleared, are not
> identical.  Why is that?
Non Wal-Logged action like visibility bits.

Andres

Andres Freund <andres@anarazel.de> writes:
> On Friday 18 June 2010 00:22:00 Josh Berkus wrote:
>> We've noticed that checksums and file sizes for the master database, and
>> slave database, even after all transactions have been cleared, are not
>> identical.  Why is that?

> Non Wal-Logged action like visibility bits.

That wouldn't affect file sizes though.  Could we have some specifics?
        regards, tom lane

Tom Lane wrote:
> Andres Freund <andres@anarazel.de> writes:
>   
>> On Friday 18 June 2010 00:22:00 Josh Berkus wrote:
>>     
>>> We've noticed that checksums and file sizes for the master database, and
>>> slave database, even after all transactions have been cleared, are not
>>> identical.  Why is that?
>>>       
>
>   
>> Non Wal-Logged action like visibility bits.
>>     
>
> That wouldn't affect file sizes though.  Could we have some specifics?
>
>             
>   

I have not noticed different file sizes, only checksums.

cheers

andrew