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Re: Online Backup and WAL archives

From: Pallav Kalva <pkalva(at)deg(dot)cc>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Morus Walter <morus(dot)walter(at)tanto(dot)de>, pgsql-admin(at)postgresql(dot)org
Subject: Re: Online Backup and WAL archives
Date: 2005-02-01 19:47:40
Message-ID: 41FFDCDC.4030207@deg.cc (view raw or flat)
Thread:
Lists: pgsql-admin
Hi Tom,

     If I want to restore to a particular point in time lets say to the 
point in time like a day back when one of my table was dropped 
accidentally and if i want restore the archive log only to that 
particular archive log file . what is the procedure we should follow ? 
just keep the archive logs in the directory until the last archive log 
file i need or is there a command something like  " restore only until 
at this archive log file " ?   Also what happens to the transaction log 
files in pg_xlog directory in this scenario ? do i have to still keep 
them or they get created by themself since i am going a day back ?

   Is this possible in postgres 8

Thanks,
Pallav


Tom Lane wrote:

>Morus Walter <morus(dot)walter(at)tanto(dot)de> writes:
>  
>
>>The documentation says 
>>' To make use of this backup, you will need to keep around all the 
>>WAL segment files generated at or after the starting time of the backup. '
>>Now I'm wondering how much of these WAL segment files do I really need
>>in order to recover the databases to a consistent state.
>>    
>>
>
>If you are satisfied with recovering to the state shortly after you
>completed the backup, then it would be sufficient to have a set of WAL
>files spanning the time period in which the backup is done.  I'm dubious
>that this is necessarily an improvement over a pg_dump backup, though.
>
>  
>
>>I expect the online backup to faster on recovery than an SQL dump, since
>>the latter would imply recreation of indexes during recovery.
>>    
>>
>
>Is that assumption founded on any hard evidence?
>
>			regards, tom lane
>
>---------------------------(end of broadcast)---------------------------
>TIP 9: the planner will ignore your desire to choose an index scan if your
>      joining column's datatypes do not match
>
>  
>



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