agree! thx
On Fri, Sep 18, 2009 at 11:07 AM, Brett Wooldridge <[email protected]> wrote: > Glad the updated statistics worked for you. The specificity of messageId > seemed extremely high, and given only 1 million rows should have been > returning sub-second results. You don't need indexes on either of the other > two fields, they won't improve performance and will slow insertion speed. > Brett > > On Fri, Sep 18, 2009 at 9:31 AM, Andrew Bruno <[email protected]> > wrote: >> >> Hey all, >> >> Sorry been flat chat for a while, but I gotta say that the query >> improved dramatically when the stats updated. >> >> When I created the index, I didnt wait for the stats to be updated. >> >> I came back the next day, and the query was running in sub seconds. >> Now ExchangeSync can run well again on this 3G database. >> >> I want to thank everyone for the awesome support, including some of >> those left or right field ideas! >> >> Cheers >> Andrew >> >> >> On Thu, Sep 17, 2009 at 7:26 PM, Knut Anders Hatlen <[email protected]> >> wrote: >> > Brett Wooldridge <[email protected]> writes: >> > >> >> You can force Derby to update statistics with this command: >> >> >> >> alter table <table-name> compress [sequential] >> >> >> >> Note this command itself might take a long time -- dozens of minutes -- >> >> but in >> >> a system like yours you could get away with running it once or month or >> >> so at >> >> some off-peak time. >> > >> > In Derby 10.5 you have a cheaper way of updating the index cardinality >> > statistics. This statement will update the statistics for all the >> > indexes on columns in MYSCHEMA.MYTABLE without doing an expensive >> > compress: >> > >> > CALL SYSCS_UTIL.SYSCS_UPDATE_STATISTICS('MYSCHEMA', 'MYTABLE', NULL) >> > >> > http://db.apache.org/derby/docs/10.5/ref/rrefupdatestatsproc.html >> > >> > -- >> > Knut Anders >> > > >
