Re: Index "Fillfactors"

This is a multi-part message in MIME format. --------------2B6656806856 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Greg Moye wrote: > > Has anyone noticed that when v7 (Specifically 7.12.UC1 for me) builds > indexes it usually leaves leaf pages rather sparsely packed?? Averages > of 700 to 1200 bytes free out of 2k bytes is common for me. > > tbcheck -pT output shows this pretty clearly, regardless of what > FILLFACTOR is set to. FWIW, V5 index build looks essentially identical. > > I'm told this might be due to the page splitting process and/or data > distribution, and that all indexes are still built top down (bottom up > v8??). Pretty amazing huh?? I woulda never thunk it. Indexes are not built top-down, as of 6.x or so. The keys are sorted, the leaf nodes built, then the rest of the tree is built up from there. Are you performing your oncheck immediately after building the index? Keep in mind that if you use a FILLFACTOR that is very high, say 90-100, then a moderate number of inserts will result in a lot of node splitting, with the resulting nodes considerably less packed than they were originally. For fairly active tables, you don't want to use too high a FILLFACTOR - 90 is about as high as you want to go. For static tables, you can push it higher. -- Dave Kosenko, Informix Professional Services **************************************************************************** While it is true that there is more than one way to skin a cat, the cat himself generally fails to appreciate the differences. --------------2B6656806856 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="IFXDISCL.TXT" ************************************************************************* Note: please do not send me email asking about features, or asking about Informix problems and how to solve them. I answer what questions I can in this forum (comp.databases.informix) when I have the time to spare. For questions on features, call your local sales rep or check out the Informix web site (http://www.informix.com). For technical problems, call Informix tech support. ************************************************************************* Disclaimer: All opinions expressed in this message are well-reasoned and insightful; needless to say, they are not those of Informix Software, its partners or lackeys. Anyone who says otherwise is itching for a fight. --------------2B6656806856--