Loading Data and Checkpoints
Scott Huppert saw checkpoints every 3 seconds while loading data with dbload, with PHYSFILE at the default 2000 KB. Jonathan Leffler explained the physical log holds before-images of pages, so new pages may be logged. Andrzej Beletsky suggested raising PHYSFILE to 50000 KB with onparams -p. June Tong thought never-initialized pages are not logged. Not conclusively resolved.
Auto-generated by Claude from the posts below — may be imperfect; read the full thread.
While setting up a new development box, I was using Dbload to migrate the data. I left my PHYSFILE at the default 2000Kb, and I was seeing checkpoints every 3 seconds. I understand that when the Physical log gets to 75% full it forces a checkpoint, but I didn't think loading data had to hit the Physical log. - Scott ___________________________________________________ Scott Huppert, Database Administrator Sonata Informix NextGen Systems Global Crossing Conferencing 12110 North Pecos St. Westminster, CO 80234 Voice: 303.633.3917 Fax: 303.633.3001 E-Mail: shupp@cfer.com
Scott Huppert wrote: > While setting up a new development box, I was using Dbload to migrate the > data. I left my PHYSFILE at the default 2000Kb, and I was seeing > checkpoints every 3 seconds. I understand that when the Physical log gets > to 75% full it forces a checkpoint, but I didn't think loading data had to > hit the Physical log. The physical log contains the 'before' images of each page. When a new page is started, therefore, the old (empty) page is copied to the physical log -- at least, in principle. I'd be delighted to be told that there's an optimization which handles previously empty pages, but I have my doubts. -- Jonathan Leffler (jleffler@informix.com, jleffler@earthlink.net) Guardian of DBD::Informix v0.95 -- see http://www.perl.com/CPAN #include <disclaimer.h>
Try to set PHYSFILE 50000Kb ( onparams -p ...)
Scott Huppert <shupp@cfer.com> '''''''' ' ''''''
<87b2t3$rg5$1@news.xmission.com>...
>
> While setting up a new development box, I was using Dbload to migrate the
> data. I left my PHYSFILE at the default 2000Kb, and I was seeing
> checkpoints every 3 seconds. I understand that when the Physical log
gets
> to 75% full it forces a checkpoint, but I didn't think loading data had
to
> hit the Physical log.
Jonathan Leffler wrote: > > Scott Huppert wrote: > > > While setting up a new development box, I was using Dbload to migrate the > > data. I left my PHYSFILE at the default 2000Kb, and I was seeing > > checkpoints every 3 seconds. I understand that when the Physical log gets > > to 75% full it forces a checkpoint, but I didn't think loading data had to > > hit the Physical log. > > The physical log contains the 'before' images of each page. > When a new page is started, therefore, the old (empty) page > is copied to the physical log -- at least, in principle. > I'd be delighted to be told that there's an optimization > which handles previously empty pages, but I have my doubts. I'm not sure about empty pages which had been used at some point in the past, but I'm pretty sure the optimization exists to not log new pages (pages which had never been initialized). June -- june_t@hotmail.com Living on Snickers bars in San Mateo