The good and bad sides of index can be explained in this way: Good: - Fast search using _simple_ queries. As far as I know more advanced queries using fore instance the Like operator may not be faster even if there is an index, especially if you use it like this "Where MYCOLUMN Like "%M�ller%"
Bad: - Every action that makes changes to the data in the table will be slower. This is caused be two things: 1 MapInfo has to update the index. 2. MapInfo creates 3 transaction files. And the TIN is the same size as the original index file !! This can however be avoided if you turn on the FastEdit Mode before doing any changes. But this also means that there is no way to undo the edits, unless you have a backup of the table. Peter Horsb�ll M�ller GIS Developer Geographical Information & IT COWI A/S Odensevej 95 DK-5260 Odense S Denmark Tel +45 6311 4900 Direct +45 6311 4908 Mob +45 5156 1045 Fax +45 6311 4949 E-mail [EMAIL PROTECTED] http://www.cowi.dk *****CHANGE OF ADDRESS - COWI's offices in Odense are now under the same roof***** On December 8th. 2003, Geographical Information & IT moved from Rugaardsvej 55, 5000 Odense C to Odensevej 95, 5260 Odense S. Please note our new telephone, direct and telefax numbers. > -----Original Message----- > From: Marty Sprenz [mailto:[EMAIL PROTECTED] > Sent: Friday, January 23, 2004 3:22 AM > To: [EMAIL PROTECTED] > Cc: [EMAIL PROTECTED]; [EMAIL PROTECTED] > Subject: RE: MI-L slow query > > > Thank you for the suggestion however creating the index takes > a very long time (15 to 20 minutes). I have to do in excess > of 400 select queries. What slows down if indexing is > active? The reason I ask is that I'll keep an eye out for > unusually slow processes. > > Marty > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] > Sent: Thursday, January 22, 2004 2:30 PM > To: Marty Sprenz > Cc: [EMAIL PROTECTED]; [EMAIL PROTECTED] > Subject: RE: MI-L slow query > > > > > > > Indexing is good, when you are selecting data. But it slows > down many other functions in MapInfo. Create it, use it, > drop it. ____________ Kent Treichel Analyst-GIS Tax Research > Minnesota Department of Revenue MS 2230 600 North Robert St > St. Paul, MN 55146-2230 651-556-6150 > > > |---------+---------------------------> > | | "Marty Sprenz" | > | | <[EMAIL PROTECTED]| > | | lting.com> | > | | | > | | 01/22/2004 01:23| > | | PM | > | | | > |---------+---------------------------> > > >------------------------------------------------------------- > ---------- > -------------------------------------------------------| > | > | > | To: "'Melissa Blackwell'" <[EMAIL PROTECTED]>, > <[EMAIL PROTECTED]> | > | cc: > | > | Subject: RE: MI-L slow query > | > | > | > > >------------------------------------------------------------- > ---------- > -------------------------------------------------------| > > > > WOW! Indexing took the select query process from > 30m to < > 1m. Thank you for the suggestion. > > Marty > > -----Original Message----- > From: Melissa Blackwell [mailto:[EMAIL PROTECTED] > Sent: Thursday, January 22, 2004 1:10 PM > To: Marty Sprenz; [EMAIL PROTECTED] > Subject: RE: MI-L slow query > > Yes Marty, Indexing is pretty much a "must" when working with > large amounts of data. > > Go into the Table>Maintenance>Table Structure & Index the ID > field and any other field which you might need to search. > (Indexing does increase the file size so you don't want to > index every field - just the ones you need like ID.) > > MI will close the Map & Browser Windows when you Index the > table, but after that you should see a dramatic improvement > in your query times. > > Melissa Blackwell > Training & CRM Administrator > Empower Geographics > Work: (847) 299-6952 x416 > Cell Phone: (847) 910-2404 > www.empower.com > > Stay informed on important news! > Subscribe to our eLetter here: <<http://www.empower.com/eLetter>> > > How will moving to a new business location impact the people > you serve? Find out with Empower Relocator! <http://www.empower.com/MapPoint/relocator.htm>> Check out our new Demographic solutions area: <http://www.empower.com/Demographics/index.htm>> Need a refresher course on MapInfo? Come to a training class and use our powerful new computers! <http://www.empower.com/pages/training.htm>> -----Original Message----- From: Marty Sprenz [mailto:[EMAIL PROTECTED] Sent: Thursday, January 22, 2004 11:57 AM To: [EMAIL PROTECTED] Subject: MI-L slow query I have a table with around 2.5 Mil records. It takes 30 minutes to do a simple select query. Is there a way, such as indexing, that I could speed up the query process? Currently I'm selecting records based on the value in an ID field in MapInfo 7.0. Marty --------------------------------------------------------------------- List hosting provided by Directions Magazine | www.directionsmag.com | To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Message number: 10068 --------------------------------------------------------------------- List hosting provided by Directions Magazine | www.directionsmag.com | To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Message number: 10069 --------------------------------------------------------------------- List hosting provided by Directions Magazine | www.directionsmag.com | To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Message number: 10073 --------------------------------------------------------------------- List hosting provided by Directions Magazine | www.directionsmag.com | To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Message number: 10075
