Thursday, March 24, 2011

Performance Tuning Queries : -

Shows active (in progress) transactions  
select username, terminal, osuser,
t.start_time, r.name, t.used_ublk "ROLLB BLKS",
decode(t.space, 'YES', 'SPACE TX',
decode(t.recursive, 'YES', 'RECURSIVE TX',
decode(t.noundo, 'YES', 'NO UNDO TX', t.status)
)) status
from sys.v_$transaction t, sys.v_$rollname r, sys.v_$session s
where t.xidusn = r.usn
and t.ses_addr = s.saddr;

Display rollback segment statistics
Select rn.Name "Rollback Segment", rs.RSSize/1024 "Size (KB)", rs.Gets "Gets",
rs.waits "Waits", (rs.Waits/rs.Gets)*100 "% Waits",
rs.Shrinks "# Shrinks", rs.Extends "# Extends"
from sys.v_$RollName rn, sys.v_$RollStat rs
where rn.usn = rs.usn;
Display database sessions using rollback segments
SELECT r.name "RBS", s.sid, s.serial#, s.username "USER", t.status,
t.cr_get, t.phy_io, t.used_ublk, t.noundo,
substr(s.program, 1, 78) "COMMAND"
FROM sys.v_$session s, sys.v_$transaction t, sys.v_$rollname r
WHERE t.addr = s.taddr
and t.xidusn = r.usn
ORDER BY t.cr_get, t.phy_io;
Regards,
Sukhwinder Singh

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