Marc, In general terms that would not be a productive use of an index, because the b-tree storing the addresses of the rows would be very deep. Depending on file and table fragmentation in the databases, there might be certain (rare) cases where it would retrieve data faster. It would always slow updates and inserts.
Bill On Wed, Jan 6, 2010 at 9:46 AM, MDRD <[email protected]> wrote: > Is it OK to index a Y/N column if you have 95% N and 5% Y > and you only search for Y? > > I was wondering if those 5% Y's would pop up faster compared > to RBase going row by row. > > Thanks > Marc > > > > > . Do not index any column with relatively few > >> distinct values (such as a Y/N column). >> >> Emmitt Dove >> Manager, Converting Applications Development >> Evergreen Packaging, Inc. >> [email protected] >> (203) 214-5683 m >> (203) 643-8022 o >> (203) 643-8086 f >> [email protected] >> >> -----Original Message----- >> From: [email protected] [mailto:[email protected]] On Behalf Of Dan >> Sent: Wednesday, January 06, 2010 8:19 AM >> To: RBASE-L Mailing List >> Subject: [RBASE-L] - Re: Update command taking forever >> >> >> Bob, >> Thanks for responding. >> 1. using latest version dated last week >> 2. QUALCOLS is set to 10 already >> >> Have not unloaded and reloaded in the last week, but that table never gets >> deletes, but that still is something to try, can't do it now till everyone >> goes home tonight and I stay late. I could try it on a backup database and >> see. I guess that is my next step. >> >> 3. Using the update on just one column where there is a non zero, I am >> getting one row updated per second and a half. So the command is working, >> but will take a long time. >> >> Dan >> >> At 08:08 AM 1/6/2010, you wrote: >> >> Dan, >>> >>> Indexes are only meant to increase the speed of identifying rows, not the >>> actual update. >>> >>> So you definitely do not want to add indexes to the columns you are >>> updating. That would >>> >>> actually slow down the process as you would now be updating the indexes >>> as well as the >>> >>> data. >>> >>> >>> >>> Updating 100,000 rows should not take too long, so something is certainly >>> askew. >>> >>> >>> >>> So some things to check... >>> >>> >>> >>> Look at your setting for QualCols >>> >>> >>> >>> R:>sho qualcols >>> >>> QUALCOLS is set to 10 >>> >>> >>> >>> If it is not set to 10, then set it. This can make a significant >>> >> difference. >> >>> >>> >>> >>> Unload and Reload the database if you have not already done so. If >>> there have >>> >>> been much row deleting etc. sometimes the database files need packed. >>> Although >>> >>> I am hard pressed to think this would cause an hours long update. >>> >>> >>> >>> Try updating just one column at a time and see if the time is different >>> and report back. >>> >>> >>> >>> Make sure you are running the latest version. There were changes made >>> that directly >>> >>> effected speed in certain cases. >>> >>> >>> >>> -Bob >>> >>> >>> ----- Original Message ----- >>> From: "Dan" <[email protected]> >>> To: "RBASE-L Mailing List" <[email protected]> >>> Sent: Wednesday, January 6, 2010 6:25:51 AM GMT -06:00 US/Canada Central >>> Subject: [RBASE-L] - Update command taking forever >>> >>> >>> >>> >>> Hi, >>> We have finally made the conversion to Turbo 8, and am having >>> troubles with my month end financial processes. I assumed it was >>> index problems and made sure there are indexes. >>> >>> Update ardetail set invcur = 0, paycur = 0 >>> >>> used to take seconds in 7.5 26 hours and counting in turbo >>> >>> in 7.5 neither invcur nor paycur had indexes. >>> I added them now, and still no increase in speed. So then I >>> thought, ok with the new indexes, lets key just off those.. >>> >>> Update ardetail set invcur = 0 where invcur <> 0 (excluding 95000 >>> rows) only 1300 should now be looked at, and this still takes forever. >>> >>> Where should I look next? >>> >>> >> >> > >
