Performance 11g

Question

Hi all
oracle 11g.2 ASM RAC under OL 5.6
i have sql statemant running by dev team and this update contain rowid
and i know when using the rowid the update will take more time to finish any way
i use the below query to find the complete %
SQL> SELECT * FROM (select username,opname,sid,serial#,context,sofar,totalwork
,round(sofar/totalwork*100,2) "% Complete"
from v$session_longops where totalwork !=0)
WHERE "% Complete" != 100;  2    3    4
no rows selected
SQL>and always it working fine with me , when i check the this query in OEM i found that query
first table scan and then sort and then update (path of the query)
when i run the above query it show me the % was increased till reach 100% (table-scan) and then finished
and in OEM it's done but till now the query still running and i don't know why my query return no rows and from OEM there is no record for this update
in top activity
also i recommend the dev to use the below parameter before running the update after i increase the undo and temp and replace the mod of this table to nologging
alter session enable parallel dml;
alter session set sort_area_size=1800000000;
alter session set hash_area_size=1800000000;please any suggestion ??? and how can i improve the update ???

Answer 1

Hi,
it was entirely accidental that this query was showing correct progress of the UDPATE statement, because it only works well if your query's execution time is mostly spent on one and only one long operation ("longop"). Apparently, because of change in the plan or the data, other operations started to take longer than they used to, or maybe concurrency issues are preventing the statement from progressing once the read part is done.
If you have the Diagnostic Pack license, then the easiest way to provide us information necessary for tuning this statement is by posting here the result of select dbms_sqltune.report_sql_monitor(sql_id => :this_sql_id) from dual (be sure to use tags to preserve formatting) together with the explain plan with the predicate section (SQL monitor doesn't contain predicate information).
Best regards,
  Nikolay
Edited by: Nikolay Savvinov on Apr 1, 2013 11:03 AM