What do these accomplish?

From: <dbaxchange.dba_at_gmail.com>
Date: 28 Nov 2005 09:05:10 -0800
Message-ID: <1133197510.195169.222060@z14g2000cwz.googlegroups.com>

Hello everyone,

I've searched metalink and on the web and could find very little documentation on this and so thought I would post it here......

While collecting database stats using the dbms_stats package and including the option for histograms on indexed columns (FOR ALL INDEXED COLUMNS SIZE AUTO), I've seen oracle submit SQL statements with the following hints:

no_monitoring
cursor_sharing_exact

What do these accomplish? They both are features within the database but how do they translate to be directives to the optimizer? Does cursor_sharing_exact hint mean that "do not share this statement if already in the library cache unless the cursor's exact"? Not really sure....

Also, I've seen the following functions being used by oracle for collecting histograms:

sys_op_descend
sys_op_lbid

The only documentation I could find on sys_op_descend on the web was this : "Used to generate the values stored for indexes with descending columns". What values are exactly being generated? Not really sure here......

Any information on this would be appreciated......

Thanks!

http://www.dbaxchange.com Received on Mon Nov 28 2005 - 11:05:10 CST