tag:blogger.com,1999:blog-3086558868352622884.post7724754026304178731..comments2023-06-05T07:33:53.363-07:00Comments on Inside the Oracle Optimizer - Removing the black magic: Improvement of AUTO sampling statistics gathering feature in Oracle 11gOptimizer Development Grouphttp://www.blogger.com/profile/17974370052224384106noreply@blogger.comBlogger5125tag:blogger.com,1999:blog-3086558868352622884.post-80208274336145843652008-01-30T13:26:00.000-08:002008-01-30T13:26:00.000-08:00Good Information. Please keep it coming.Good Information. Please keep it coming.Mayimbehttps://www.blogger.com/profile/14568927676843619322noreply@blogger.comtag:blogger.com,1999:blog-3086558868352622884.post-83382956832808455922008-01-23T13:33:00.000-08:002008-01-23T13:33:00.000-08:00I second Robert's questions; especially I would li...I second Robert's questions; especially I would like to know a bit more about the autosampling algorithm, for the reasons Robert expressed but also out of sheer curiosity.Alberto Dell'ERahttps://www.blogger.com/profile/15037836614464523039noreply@blogger.comtag:blogger.com,1999:blog-3086558868352622884.post-46410774103057544282008-01-23T07:08:00.000-08:002008-01-23T07:08:00.000-08:00Pretty interesting stuff! However, I am missing f...Pretty interesting stuff! However, I am missing few bits of information:<BR/><BR/>What does "deterministic statistics" mean? In how far were statistics non deterministic in older versions of Oracle? Does this refer to the selection of rows for analysis?<BR/><BR/>A column "Auto sampling in Oracle 10g" in table 2 would be great so we can see the difference in accuracy between Oracle 10 and 11 auto sampling.<BR/><BR/>And a hint about what changed in the sampling process would be great in order to help DBA's decide when they can safely rely on auto sampling and when they cannot.<BR/><BR/>Just my 0.02 EUR.roberthttps://www.blogger.com/profile/01724179181550310220noreply@blogger.comtag:blogger.com,1999:blog-3086558868352622884.post-11838807079300212572008-01-23T06:36:00.000-08:002008-01-23T06:36:00.000-08:00And what was the accuracy of the 10g AUTO sampling...And what was the accuracy of the 10g AUTO sampling?Fladohttps://www.blogger.com/profile/04901763101139511192noreply@blogger.comtag:blogger.com,1999:blog-3086558868352622884.post-42747930031222556772008-01-22T19:00:00.000-08:002008-01-22T19:00:00.000-08:00This is fantastic information. We use Oracle 9i c...This is fantastic information. We use Oracle 9i currently (10g shortly) and find the AUTO sample size undesirable in our current implementation.<BR/><BR/>What we have found in our Data Warehouse is that 90-95% accuracy is more desirable than near 100% accuracy if there is a significant speed increase in gathering stats.<BR/><BR/>I would hope in a future version of Oracle that perhaps we could set a target accuracy as a parameter. I wonder what difference that would make in the speed of gathering stats.<BR/><BR/>Regardless, we would look forward to playing with the new enhancements in 11g. Thanks!Catmandohttps://www.blogger.com/profile/10138985602641512594noreply@blogger.com