Re: Indexes on highly duplicate columns - Performance?

We have dealt with that problem and determined that highly duplicate values make for performance difficulties. I believe it is because of excessive index manipulation that occurs expecially in insert activities. With only 800 rows it might have little effect. On the other hand, unless the table is terribly volatile, the additional index space probably costs you little in memory, and probably nothing in disk space allocated. Good luck -- Con Woodall Colorado St. U.; Veterinary Teach. Hosp.; cwoodall@vth1.vth.colostate.edu On Wed, 7 Dec 1994, Kerry Sainsbury wrote: } We have a little column (CHAR(2)) in a table of about 800 rows. } There are about 6 different values in the column. } } People here (who pay me money) reckon I should create an index on it } that looks like this: } } So: CREATE INDEX myindex ON mytable (little_column, other_uniqueish_column) } } Not: CREATE INDEX myindex ON mytable (little_column) } } Their logic states that one should add some other columns into the } index so that the B-Tree isn't filled with lots of duplicate records. } } Is this sensible? Anybody else heard this theory before? JL? } } Regards, } Kerry S } --------------------------------------,------------------------------------- } Kerry Sainsbury, kerry@kcbbs.gen.nz | THE INFORMIX FAQ } Quanta Systems, Auckland, New Zealand | kcbbs.gen.nz:/informix/* } | mathcs.emory.edu:/pub/informix/faq/* } +64 9 377-4473 (work) 276-5546 (home) | quasar.ucar.edu:/? }