Re: PostgreSQL Data Loss - Mailing list pgsql-hackers

From Zdenek Kotala
Subject Re: PostgreSQL Data Loss
Date
Msg-id 45BA7A10.5050700@sun.com
Whole thread Raw
In response to PostgreSQL Data Loss  (BluDes <DESPAMMAMIdarocchi@PERFAVOREtiscali.it>)
List pgsql-hackers
If data are deleted then they are still stored in database until VACUUM 
cleans them. You can look by some hex viewer, if you see some know text 
data there. Or I think there is also some tool which dump tuple list 
from pages.

You can also see deleted data if you change current transaction ID. But 
I not sure if it is simply possible.

Before experiments, do not forget backup of database files.

Zdenek

BluDes wrote:
> Hi everyone,
>  I have a problem with one of my costomers.
> I made a program that uses a PostgreSQL (win32) database to save its data.
> My customer claims that he lost lots of data reguarding his own clients 
> and that those data had surely been saved on the database.
> My first guess is that he is the one who deleted the data but wants to 
> blame someone else, obviously I can't prove it.
> 
> Could it be possible for PostgreSQL to lose its data? Maybe with a file 
> corruption? Could it be possible to restore these data?
> 
> My program does not modify or delete data since its more like a log that 
> only adds information. It is obviously possible to delete these logs but 
> it requires to answer "yes" to 2 different warnings, so the data can't 
> be deleted accidentally.
> 
> I have other customers with even 10 times the amount of data of the one 
> who claimed the loss but no problems with them.
> He obviously made no backups (and claims whe never told him to do them 
> so we are responsible even for this) though the program has a dedicated 
> Backup-section.
> 
> Any suggestion?
> 
> Daniele
> 
> ---------------------------(end of broadcast)---------------------------
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