[EMAIL PROTECTED] wrote: > 2. Performance of the TAB file - you'll need to pack it often to ensure that > the spatial indices don't get knackered (technical term)
Knackered? Is that the same as the Canadian english 'hosed' or the American english 'fubar?' And who knows how the Aussies say it, but I bet it's colorful! But seriously, there's a section in the MapBasic Users Guide called "Multi-User Edits" that's worth a read for anyone whose about to wade into this swamp. Apparently MapInfo thinks we can do it. The trick seems to be to design an application/environment where the tables being edited by multiple users are opened for writing for as short a time as possible, and that all applications that access these tables are prepared to retry or cancel read and write operations intelligently. Do this correctly and your system shouldn't cough up its socks even if someone opens a tab file interactively and starts to monkey around with it. At worst, your application should just let users know that a table is locked by another user and either try again or quietly back up and let you do something else. Performance is always an issue with MapBasic, and usually some form of local temporary tables are needed to edit existing objects without tying up the whole table. It gets tricky when posting edited objects back to a table because not only do you have to update just those that have changed but handle new and/or deleted records as well. I think the hardest problem to solve is to write an application so that it can tolerate 'access denied' situations and be prepared to go to Plan B if necessary. Or handle a power failure where recovery may require resetting file & record locks set previously by the application. These are simply multi-user edit issues and have to be dealt with no matter what DBMS you're using. Imagine the fun we'll have in the near future when tables are scattered across the Internet and our applications must run 24/7 and communications failures have to be reckoned with as well! - Bill Thoen --------------------------------------------------------------------- List hosting provided by Directions Magazine | www.directionsmag.com | To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Message number: 10333
