On 26/09/11 17:06, Ann Harrison wrote: >> Is there a way of finding out how many pages are used to store a given >> table? Or documentation about how the mapping from tables to memory and >> disk pages are implemented on firebird? Maybe http://www.firebirdsql.org/file/documentation/reference_manuals/reference_material/Firebird-Internals.pdf might help, it's a work in [slow] progress though. :-(
HTML version is on-line at http://www.firebirdsql.org/file/documentation/reference_manuals/reference_material/html/fb-internals.html. > Pretty simple. If you care about detail, look at ods.h for the size of the > PAG structure and the exact layout of a generator page. For a rough > approximation of the number of generators on a page, divide the page size by > 8. If I remember, (page-size-32)/8 gives the maximum number of sequences on a page. For a 4K page that's 507. There is also a maximum of 32,767 sequences per database. > Note that this algorithm works ONLY for generators which are not normal > table data. Figuring out how many data records fit on a page is an advanced > exercise. http://www.firebirdsql.org/file/documentation/reference_manuals/reference_material/html/fbint-page-5.html might help explain the difficulties - think Run Length Encoding and NULLs etc. Cheers, Norm. -- Norman Dunbar Dunbar IT Consultants Ltd Registered address: Thorpe House 61 Richardshaw Lane Pudsey West Yorkshire United Kingdom LS28 7EL Company Number: 05132767
