Re: Maximum extents

> > 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). Yes. The max number of extents varies with each table and depends on the number of indexes and special columns (varchar, text) in the table. These take away page space that could be used by slot 5 which contain extent information.