RE: Logical logs
Girish,
Why is it difficult to manage more no. of logs from admin point?
If I increase the size of each log to 8 MB, in case of database failure I
will be loosing 8 MB of data(transactions) in case failure occured before it
was backed up.
As you suggest to increase LTXHWM & LTXEHWM are 80 and 90, what will happen
if there is a long transaction and the engine doesn't have enough space to
roll back the transaction even though we have LBU_PRESERVE set to 1? Will it
crash the server? or will it freeze all activity?
I do agree that tunning the application is the best solution to avoid long
trx, but its a long process.
Thanks
Vinod Bhansali
>From: Girish Punjabi <girishpunjabi@my-deja.com>
>Reply-To: Girish Punjabi <girishpunjabi@my-deja.com>
>To: informix-list@iiug.org
>Subject: RE: Logical logs
>Date: Tue, 23 May 2000 23:51:17 GMT
>
>HI Vinodh,
>
>Nothing wrong with more logical logs except that is is inefficient from
>an administrative point of view.
>Instead of having 120 logical logs of 2MB each you can have 30 logs of
>8MB each.You can also set LTXHWM & LTXEHWM are 80 and 90
>respectively.We have overcome the long transaction problem here by
>deviating from Informix suggested values of 50 and 60.
>Also , as William suggested, you need to have a look at the code as
>well , as no amount of tuning can help if the code is inefficient.
>
>
>In article <8ge25v$s64$1@news.xmission.com>,
> William Rice <ricew@operamail.com> wrote:
> >
> > I do not feel their is anything wrong with having that many logical
>logs.
> > One thing you might want to establish is why you are having long
>transactions
> > and whether or not what is being done is required to be one
>transaction.
> >
> > If the cause is a process which is required to be updated in one
>transaction
> > you have no choice but to increase the number of logs.
> >
> > If the cause of the long transactions is a purge or something of that
>nature,
> > which can be done in smaller increments without effecting the
>validity of the
> > data, you might want to look into making the purge use a select cursor
> > and deleting each record and committing periodically.(If their is a
>better way
> > to do this I would love to hear it.) If you just increase the number
>of logs,
> > as
> > the amount of data purged grows, the likelihood of hitting a long
>transaction
> > again grows. A program which commits at regular intervals bypasses
> > these emergencies.
> >
> > If the cause of the long transactions is a lock held for an
>inordinate period
> > of time, it might be worth implementing some sort of timing mechanism
> > to cause the user to abort after holding a lock for some period of
>time,
> > or rewriting the application to not hold locks while waiting for user
>input.
> >
> > Hope this helps,
> > Will
> > >===== Original Message From "Vinod Bhansali" <iiug@hotmail.com> =====
> > >In our system, I am noticing Long Transactions being caused
>sometimes. We
> > >have 80 log files, each of size 2048. LTXHWM & LTXEHWM are 50 & 60.
>I don't
> > >want to increase them. I am planning to increase the no. of log
>files to 120
> > >or to 160. Are there any pros and cons of having more no. of logical
>log
> > >files. We have continuous logical log backup running and we take
>zero level
> > >db backup daily using ontape.
> > >
> > >Thanks in advance
> > >Vinod Bhansali
> >
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