Re: Maximum extents

Mickey Mestel wrote: > > Mark D. Stock wrote: > > > I didn't see the original question, but the limit of 8 extents per table > > was up to version 5.x, because only the first 8 extents are tracked in > > SHM. > > In version 6.x onwards extents are tracked in the virtual portion of > > SHM, > > and therefore the number is dynamic. > > cool. i wasn't aware of that. thanks for the update. it's good when > things like this are made dynamic. > > > This is not so true now in 7.x, but is still a good rule of thumb to > > bear > > in mind, in order to reduce fragmentation of tables. > > yes, still, you want to keep the number of extents as low as possible, > performance degradation due to fragmentation. > > mickm In 5.x the partition page (slot 5) contains the extent address information used to locate the physical data page. Each extent takes up 8 bytes. There are other slot entries on this page which expand with the table data. The reason for the 200+ number is due to the page size of 2k / 8, but varying expansion of other slots data (or something like that). -- Jay Engel AG Communication Systems, Phoenix, AZ. http://www.agcs.com Voice: 602 582-7324, Fax: (602) 582-7697, Office: G10 Internet: engelj@agcs.com