Re: npused < 0 - alive and well in 7.11.UC1 (fwd)

Tom I could not send this directly to you, so I am posting my response on the List, THANKS for you RESPONSE, YET: We did the tbunload/tbload, the only thing it did was unfrag that tables. I have a program that runs from cron to correct this problem of neg npused, yet for some reason the numbers still showed negative in the tbcheck -pT report, for a very few tables. Now I had the whole system to myself during this processing and my npused correction happened before and after the tbunload/tbload. Got any ideas or other explanations? Thanks Cheryl Kendricks E-mail: cherylk@spamis.jcdc.doleta.gov ---------- Tom sent me the following message ---------- Date: Thu, 16 Nov 95 14:46:23 MET From: tom <hogarty.pad@sni.de> To: cherylk@spamis.jcdc.doleta.gov Subject: Re: npused < 0 - alive and well in 7.11.UC1 > > I want to hear more about this one myself guys. It's caused me more grief > then I want to convey. I'm in that number crunch mode, and begging for disk > space (the part of being a DBA, no one enjoys). > Hi Cheryl, I may not be completely in tune here but I think the major problem with this npused < 0 was/is that the optimizer takes the number of pages used into account before hauling pages into the buffer pool. Whenever npused is shown as < 0 then the path over this table is favoured. There is a *fix* for this bug which involves setting the npused equal to nrows / (pagesize/(rowsize+4)) I have found that it improves the optimizer in magnitudes. If you are looking to win back storage space might I suggest doing a tbunload/tbload or concentrate recovering the holes swiss-cheesed into your storage space by clustered indexes ? > > On 14 Nov 1995, Radio Spares wrote: > > } > } Dear All, > } > } Remeber the old npused < 0 bug with update statistics (bug #14829) that was > } meant to be fixed in 5.02. > } > } Jason Harris (RSWA) > } > If I can further help please mail me direct. Best Regards, Tom Hogarty Siemens Nixdorf Informationssysteme Paderborn, Germany e-mail : hogarty.pad@sni.de