Re: lchwaits, read aheads

Manoj, Referring to page 40-86 in the ODS Admin Guide Vol2, ixda-RA refers to the count of read-aheads from index leaves to data pages. Put another way, its the number of read-ahead pages resulting from an optimization path of INDEX PATH wherein the query reads the index and then the data page. idx-RA refers to the count if read-aheads traversing index leaves. Put another way, it is the number of read-ahead pages resulting from an optimization path of INDEX KEYwherein the entire query can be satisfied by an index and does not require a page read to the table. da-RA refers to the count of data-path-only scans. Otherwise known as SEQUENTIAL SCAN. In your example, 32,188 read-ahead pages were used out of the 32,232 read-ahead pages retrieved. That means only 44 pages were abandoned. That is pretty good (99.86%). You may benefit from increases these parameters a little. But watch for this percentage to drop off as it is an indication that you are reading in too much and wasting I/O. Now, in the event that I missed something, I'm sure my esteemed cohorts here in c.d.i. will complete anything I missed. Take Care, Chuck. +++------------------------------------------------------------------------- -------------------+++ Chuck Ludwigsen <cludwigs@hotmail.com> Sr. Engineer - Summit Data Group <chuckl@summitdata.com> President - Memphis Informix Usr Grp <miug@hotmail.com> +++------------------------------------------------------------------------- -------------------+++ Manoj <manoj@mailhost.twowaytv.co.uk> wrote in article <5vbc7r$9jj@cssun.mathcs.emory.edu>... > > All, > > Are there any guidelines for the below ? > > ixda-RA idx-RA da-RA RA-pgsused lchwaits > 4398 29 27805 32188 55 > > Thanks, > > Manoj Schroff, > Two Way TV Ltd, UK > +44(0)181 996 8221 > manoj@mailhost.twowaytv.co.uk > http://www.twowaytv.co.uk > > >