Thread

1. Re: [HACKERS] vacuum analyze

   Tom Lane <tgl@sss.pgh.pa.us> — 1999-09-02T15:33:36Z

   Michael Simms <grim@argh.demon.co.uk> writes:
   > But after 4 days of frustration, I just want to be sure - nobody else
   > has found the problem and solved it have they? I just dont want to
   > waste my time on this if someone else has found the cause...
   
   Let's see ... I know that removing pg_vlock while vacuum is running
   will lead to a coredump after vacuum finishes (it doesn't recover
   cleanly after its attempt to unlink pg_vlock fails).  I think I know
   how to fix that but it's not done yet.  The same problem could affect
   any error that is detected between vacuum's internal transactions.
   Do you get any error reports in the postmaster log when there is a
   crash?
   
   Beyond that, I don't recall having heard of any recent fixes that affect
   vacuum.
   
   If you can create a reproducible example then more people could poke
   at it, so that seems like the avenue to focus on.
   
   			regards, tom lane
   
   

2. Re: [HACKERS] vacuum analyze

   Michael Simms <grim@argh.demon.co.uk> — 1999-09-02T19:40:54Z

   > 
   > Michael Simms <grim@argh.demon.co.uk> writes:
   > > But after 4 days of frustration, I just want to be sure - nobody else
   > > has found the problem and solved it have they? I just dont want to
   > > waste my time on this if someone else has found the cause...
   > 
   > Let's see ... I know that removing pg_vlock while vacuum is running
   > will lead to a coredump after vacuum finishes (it doesn't recover
   > cleanly after its attempt to unlink pg_vlock fails).  I think I know
   > how to fix that but it's not done yet.  The same problem could affect
   > any error that is detected between vacuum's internal transactions.
   > Do you get any error reports in the postmaster log when there is a
   > crash?
   
   ahem, well, to be honest, Ive never found any documentation on how to
   read the logs *embarrassed smile*.
   
   template1=> select * from pg_log;
   ERROR:  pg_log cannot be accessed by users
   
   That happens with any account.
   
   It COULD be a problem with that, as I have a crontab process that vacuums
   everything every 24 hours, but also I perform some minor vacuums in the
   meantime, some of which may occur when the main vacuum is happening. I didnt
   notice that as a pattern, but it certainly COULD be that. I'll check into it.
   
   > Beyond that, I don't recall having heard of any recent fixes that affect
   > vacuum.
   > 
   > If you can create a reproducible example then more people could poke
   > at it, so that seems like the avenue to focus on.
   
   Yup, well, if I could get it to happen *at all* any more, I could poke around,
   as I am running the backend that is handling the vacuum under gdb. If I
   find a reproducable way I will certainly report it here.
   
   Thanx
   
   						M Simms
   
   

3. Re: [HACKERS] vacuum analyze

   Christof Petig <christof.petig@wtal.de> — 1999-09-08T11:16:59Z

   Tom Lane wrote:
   
   > Let's see ... I know that removing pg_vlock while vacuum is running
   > will lead to a coredump after vacuum finishes (it doesn't recover
   > cleanly after its attempt to unlink pg_vlock fails).  I think I know
   > how to fix that but it's not done yet.  The same problem could affect
   > any error that is detected between vacuum's internal transactions.
   > Do you get any error reports in the postmaster log when there is a
   > crash?
   >
   > Beyond that, I don't recall having heard of any recent fixes that affect
   > vacuum.
   >
   > If you can create a reproducible example then more people could poke
   > at it, so that seems like the avenue to focus on.
   >
   >                         regards, tom lane
   
   Perhaps the bug I reported on pgsql-bugs about a week ago has some relation
   to this problem:
   I had been able to reproducibly (?) crash postmaster with my example
   program (a loop of
   update table) combined with several vacuum commands in a seperate task.
   As the sice of the table's index grows a failure almost gets certain.
   
   If you think the program might help you, contact me or look into bugs'
   archives.
   
   Regards
         Christof