| v$sess_io info is not changing. [message #349409] |
Sun, 21 September 2008 10:01  |
shrinika
Messages: 306
Registered: April 2008
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Senior Member |
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Dear all,
My understanding is, v$sess_io contains one record for each session. The record contains
values for CONSISTENT_GETS,DB_BLOCK_READS are always for the latest query in the seesion.
In my database, i have only one session for username = 'SCOTT'.
scott@DB1.US.ORACLE.COM> select count(*) from emp1;
COUNT(*)
----------
13762560
scott@DB1.US.ORACLE.COM>
SQL> ;
1 select consistent_gets,physical_reads from v$sess_io
2* where sid in(select sid from v$session where username='SCOTT')
SQL> /
CONSISTENT_GETS PHYSICAL_READS
--------------- --------------
255718 161831
SQL>
The above consistent_gets,physical_reads are reasonable for selecting huge number of records in emp1 table.
Now i run the another query which has only 14 records.
scott@DB1.US.ORACLE.COM> select count(*) from emp;
COUNT(*)
----------
14
scott@DB1.US.ORACLE.COM>
SQL> ;
1 select consistent_gets,physical_reads from v$sess_io
2* where sid in(select sid from v$session where username='SCOTT')
SQL> /
CONSISTENT_GETS PHYSICAL_READS
--------------- --------------
255721 161832
SQL>
Now the consistent_gets/physical_reads are slightly changed. But this count is very high for selecting only 14 records.
Can any one please explain me on this?
Thanks.
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