Re: Sizing Online databases.

Ric wrote (from the address of Paul Middleton <paulm@compans.com>) : >We are just about to undertake a conversion from Standard Engine to >Online version 5 on a group of SCO 3.2.4.2 platforms. >Can anyone recommend or provide a utility to 'guestimate' the amount of >space we will require based on the calculations shown in the >Informix-Guide to SQL? I don't think you need to be that accurate. I just divide 2020 (Page Size of 2048 less OnLine overhead) by the row size of the table and then truncate. This gives the Rows per Page. Then divide the initial number of rows by this amount to get an initial number of pages (I usually round this up to a power of two - I'm not sure quite why). If the indexes are significant (ie a long key, a short row, or huge number of rows) then I add 20% or so. Since your data is all added at once it doesn't matter if you get the number too small because the extra rows will be placed into NEXT SIZE areas which will be added to the initial extent. Working out next size is a little trickier. The OnLine course I went on recommended a seventh of the EXTENT SIZE (since you want to keep the number of extents to 8 or less, this gives the table room to double). I use the following sort of guide, but it will need adjusting upwards if you have long rows (ie > 150 chars) or significant indexes. Static Table NEXT SIZE 8 Basically Static NEXT SIZE 16 Steadily Growing NEXT SIZE (1/4 of EXTENT SIZE) Dynamic NEXT SIZE (1/2 of EXTENT SIZE) (Dynamic tables are like transaction logs or error logs that added to daily and purged regularly). Obviously, disk space requirements should be bourne in mind. Don't forget that the SIZEs specified in CREATE TABLE are in kilobytes, whereas those reported by "tbcheck -pe" are in Pages, which should be doubled to get kilobytes (assuming Page Size = 2048). Hope this helps. Cheers, Brent Jackson. brent@advgroup.co.nz Phone : 64-9-3610613 Fax : 64-9-3764210