Re: AW: Plans for solving the VACUUM problem

Barry Lind wrote:
>
>
> Zeugswetter Andreas SB wrote:
>
> >>> Vadim, can you remind me what UNDO is used for?
> >>
> >> 4. Split pg_log into small files with ability to remove old ones (which
> >>    do not hold statuses for any running transactions).
> >
> >
> > They are already small (16Mb). Or do you mean even smaller ?
> > This imposes one huge risk, that is already a pain in other db's. You need
> > all logs of one transaction online. For a GigaByte transaction like a bulk
> > insert this can be very inconvenient.
> > Imho there should be some limit where you can choose whether you want
> > to continue without the feature (no savepoint) or are automatically aborted.
> >
> > In any case, imho some thought should be put into this :-)
> >
> > Another case where this is a problem is a client that starts a tx, does one little
> > insert or update on his private table, and then sits and waits for a day.
> >
> > Both cases currently impose no problem whatsoever.
>
> Correct me if I am wrong, but both cases do present a problem currently
> in 7.1.  The WAL log will not remove any WAL files for transactions that
> are still open (even after a checkpoint occurs).  Thus if you do a bulk
> insert of gigabyte size you will require a gigabyte sized WAL
> directory.  Also if you have a simple OLTP transaction that the user
> started and walked away from for his one week vacation, then no WAL log
> files can be deleted until that user returns from his vacation and ends
> his transaction.
   As  a  rule  of  thumb,  online  applications  that hold open   transactions during user interaction  are
considered to  be   Broken  By  Design  (tm).   So I'd slap the programmer/design   team with - let's use the server
boxsince it doesn't contain   anything useful.
 


Jan

--

#======================================================================#
# It's easier to get forgiveness for being wrong than for being right. #
# Let's break this rule - forgive me.                                  #
#================================================== JanWieck@Yahoo.com #



_________________________________________________________
Do You Yahoo!?
Get your free @yahoo.com address at http://mail.yahoo.com