Re: Initial Extents

An extent can be no larger than the largest collection of contiguous pages within a chunk. Thus, if you start with an empty chunk, you are limited to 2 GB (maybe 4 GB with your 4 KB page size, I don't know) minus whatever overhead there is in the chunk - usually 53 pages for the initial chunk in a dbspace, 3 pages for additional chunks. If (IF!) the engine supports 4 GB chunks with 4 KB pages, then the initial extent size does not sound outrageous. If you are limited to 2 GB per chunk, then your 3.3 GB primary extent won't work. The sizing of next extents depends on how much data is being added on a daily/weekly/monthly/yearly/etc. basis and how many extents you are willing to allow. If each table is in its own dbspace, extent compression should make the next extent size a non-issue, as new extents will just be added on to the prior extent, at least until you fill the chunk. Mark Collins mcollins@us.dhl.com Everybody at some level realizes that the calendar is a fairly arbitrary thing, invented by humans, for reasons that have more to do with how committees are structured than with anything that's really happening in the heavens. And yet people look at the fact that the calendar is about to turn 2000, and assume there's some deity who thinks that the base 10 counting system is pretty darn important, and make all sorts of predictions of doom and gloom as a result. To me, that tells you everything you need to know about human beings -- and a whole lot about the market for the NC. Scott Adams, creator of _Dilbert_ ------------------------ From: Herb Blacker <herbb@jcdcrs4.jobcorps.org> Subject: Initial Extents Date: Tue, 24 Feb 1998 13:00:33 -0600 (CST) To: Informix List on WWW <informix-list@iiug.org> Is there an upper limit to initial extents? I'm running ODS 5.02 and I've got one table at 846,000 pages, and several at 300,000-400,000 pages, including indexes. Calculating the extent size at 4KB per page, my largest initial extent size is around 3,385,000 KB. Is this reasonable? Should the next extent size be declared at 20% of initial? I've read TFM, and it doesn't give any limit. TIA, ------------------------------------------------------------------------ Herb Blacker Cimarron, Inc. Database Administrator - DOL Job Corps San Marcos, Texas ------------------------------------------------------------------------ ---------------End of Original Message-----------------