Re: missing page when calculating extents

1 page is always assigned to the bit-map page. Do a tbcheck -pT on the table and you will see all of this information. Therefore by default a table always uses at least 1 page (extent) rather it contains data or no data. On Wed, 13 Dec 1995, Lucy Lastik wrote: } Apologies if this is old hat ... } } I have been trying to calculate extent sizes, I faithfully followed what it } said in chapter 10 of the Tutorial, but I found an interesting 'problem' } } take for example a table with a rowsize of 12 bytes and no indexes } the number of rows per page should work out as } (pagesize-28)/(rowsize+4) } = (2048-28)/(12+4) } = 2020/16 } = 126 } } I should therefore be able to fit 4*126 = 504 rows in 4 pages (one 8K extent) } However, I can only fit 3*126 = 378 rows in 4 pages; when I insert the 379th } row } I get a second extent. } The same applies to other extent/row sizes, there is always one "missing" page. } } Is this because OnLine always wants at least one empty page or is it because } the "missing" page has some other info on it? } And what about Indexes, the calculations in chapter 10 seem way out. } When I added a 4 byte index to my table, I could only fit 669 rows into 12 } pages } } any clues anyone?? } } [machine = HP-UX A.09.04 E 9000/847, OnLine = 5.02.UC6] } -- } John Cooke } AT&T Network Systems UK } Though the opinions are mine, they remain the intellectual property my employer } }