Re: Update statistics high vs medium

Susanna, If you are using wild card search or uses "match/like/subscripts" the query cannot use index even if there is an index on the column(s). So update statistics cannot have any effect in performance of your query. You should get the same result even if you never run update statistics. I will be interseted in seeing your query and sqexplain.out. Cheers Chung-Wong, Susanna@EDD wrote in message <6kibp5$t0p$1@news.xmission.com>... > >Hi, we are running Informix ODS v7.23 on AIX 4.2. There is a table with >27000 records look like this: > TABLE dot > ( dot_serial_num char(11) not null PK, > dot_title char(82), > create_dt date indexed) > >We have several queries that join multiple tables including this DOT >table and they perform wild card search on dot_title like this: >dot_title like '%CLERK%'. I found out if the update statistics is not >run correctly for this column, the optimizer chooses to sequential scan >the other tables in these queries. And I found out only update >statistics medium works for this column: > Update statistics medium for table dot(dot_title) distributions only> >Originally, I run these two statements everyday: > Update statistics low;