tkprof question regarding cr and cur values
Date: 17 Feb 93 20:11:30 GMT
Message-ID: <C2M037.7GA_at_inews.Intel.COM>
I am trying to understand more about cr, cur values in tkprof output.
when I execute select field1 from table1 where field1='somevalue';
(assuming no indexes on table1)
the execution plan is "TABLE ACESS FULL (TABLE1)"
however the tkprof output shows
Phys cr Cur Rows Parse 0 0 0 Execute 0 0 2 0 Fetch 5 10 0 2 a) why are there 2 buffers in CUR mode ? (CUR is for modifying trans) b) why are there 10 in CR mode ? (CR is for consistent read) There are NO other users or transaction in database. then whay are the buffers read in CR mode at all ?
Strangely if I create anotehr table as "Select table2 as selct * from table1" and then run the tkprof output I get
Phys CR CUR Rows Parse 0 0 0 Execute 0 0 2 0 Fetch 10 10 0 2
why should the buffers increase in Phys,cr. or in other words why should Phys be less in case of table1 ?
If it really matters I am using Oracle v6.0.33.+ on AT&T Unix 5.4 there are about 700 records in table.
and select count(distinct substr(rowid,1,8)) from table1 (also table2) gives me 10 (which I guess is unchained blocks)
there is no likelihood of chaining as pctfree is 15% and I have not done any updates to the data.
Aniruddha Kortikar (kortikar_at_mipos2.intel.com)
E-mail : kortikar_at_mipos2.intel.com | A billion here, a billion there ... Phone(W): 408 765 5515 | pretty soon it adds upto real big money
Received on Wed Feb 17 1993 - 21:11:30 CET