Re: More Turbo Informix questions

Since no-one else seems to have come back on this one ... Cheryl Gross writes - > How do indexes work in Turbo Informix? I don't need a real technical > explanation. Indexes are created in the same (raw) disk space used for data: index pages are used rather than data pages to hold the information. Neither indexes nor data are readily visible to users without going thru the engine interface. > I just need to know the differences in plain 2.10.00B Informix > and Informix Turbo SE uses normal unix files, so you can see the amount of disk used, names of the files, etc., with "ls". Turbo/OnLine uses raw disk (or chunks of pre-assigned cooked disk), so you can't. > and how they handle index corruption in Informix Turbo. Badly 8^) It doesn't happen very often, tho', and is a lot safer than SE because of the physical and logical recovery mechanisms. > Understand that 1987 version of Informix is a little out-dated for most > of you all but it happens to be what we have to use on most of our systems. > > We could do check table and repair table under our old version of Informix. bcheck and the like, to fix C-ISAM files. > Under this Turbo Informix 2.10.03G now the database itself is transparent. As in, you can't see it with "ls", because it's on raw disk and not normal unix files. One of mine just went opaque ... > The book says that check table and repair table isql commands are no longer > valid instructions. Yup. > How do we find out if our problem with the system hanging is corrupted > indexes? How do we repair them? With Turbo and OnLine, there is a utility called tbcheck that will verify the integrity of the database: normal checks would be the system catalogs, the data pages (= tables) and index pages (= indexes). This won't indicate whether the data is ok from the application point of view (as in, whether you can JOIN across two columns you intend to join on) but checks informix data structures for consistency (as in, indirection pointers point somewhere sensible, indexes are usable). Turbo comes with a watered-down version of tbcheck: if possible, use OnLine on your systems, it's got some of the Turbo bugs removed and it's a lot more versatile (multiple DBs, for example). In general, if there are corruption problems with your database, there will be messages in the turbo.log file indicating corrupt pages or similar. If you see anything more interesting than "Checkpoint Completed" you might like to post it. tbcheck should provide rather more information and, at least on OnLine, allow you to clean up the mess. In the meantime, how 'bout a cron job to drop and recreate the indexes, possibly clustering the table at the same time ? > Cheryl Gross > Red River Army Depot > Information Center > Texarkana, Texas 75507 > > (903) 334-3518 Hope this helps, if it isn't specific enough mail me and I'll try to do better. -- Cheers - Tony. *********************** LAST FEW DAYS AT THIS ADDRESS ********************** Tony Heskett: theskett@lhr-sys.ssf-sys.dhl.com | Vox: (+44) 81 747 8330 DHL Systems : Kings House, Great West Road, TW8 9HS | Fax: (+44) 81 747 0875