Re: Should a DB vacuum use up a lot of space ?

On 08/06/2016 12:01 PM, Philippe Girolami wrote:
> Thanks to Tom & Adrian, here’s what happened (my version was 9.1, sorry I forgot to mention it)
>
> 1) 10 hours after my email, the VACUUM had used up about 3.5TB but had stopped using up more disk space, it was now
“simply”reading data from the file system 
> 2) I attempted to interrupt using CTRL-D to no avail so I interrupted with CTRL-C. That stopped it with a clean
message(but did not relinquish filesystem space) 
> 3) I exited the backend successfully using CTRL-D and relaunched it with the additional “–r” command line argument
> 4) I ran the query to see which tables were the “oldest” and did not recognize the ones before I started the
vacuuming(encouraging!) 
> 5) I ran CHECKPOINT on the backend and got all the disk space back
> 6) I realized that the message regarding wraparound was no longer an ERROR but a WARNING so I was able to restart
postgres“normally” 
> 7) I ran a query based on my previous query to build VACUUM VERBOSE commands on the tables with the oldest
transactionids and wrote it to a text file and then execute that file, I now have tens of millions of transactions back
andcan restart my server. I’ll do the rest of the VACUUM maintenance during low-load periods. 

Thanks for the feedback it is nice to 'close the loop' on an issue.

>
> Cheers
> Philippe
>
>


--
Adrian Klaver
adrian.klaver@aklaver.com