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Poor performance while selecting or deleting from DR$WAITING

Poor performance while selecting or deleting from DR$WAITING

2005-03-01       - By Naveen

Reply:     1     2  

Hi All,

Firstly, I have changed my Display name from New DBA
to my original name. The reason I kept it as New DBA
was to highlight the fact that I was just a novice and
be treated likewise :-)

My apologies if it offended anyone.

Back to the question. After tracing a slow running
transaction, I noticed that the 2 queries which took
close to 95% of the response time were on DR$WAITING.
One was a SELECT and the other was a DELETE.

I don't know a heck about this table except that it is
in CTXSYS schema and probably has got something to do
with Oracle Text or Intermedia option.

Please see the relevant extract from the trace file
(formatted using tkprof). Please bear with me if the
output doesn't look properly formated in this email.

Misses in library cache during parse: 0
Optimizer goal: CHOOSE
Parsing user id: 29     (recursive depth: 2)

Elapsed times include waiting on following events:
 Event waited on                             Times  
Max. Wait  Total Waited
 -- ---- ---- ---- ---- ---- ---- ---- --   Waited
-- ---- --  -- ---- ----
 db file sequential read                      2013  
   0.00          0.08
 db file scattered read                       7838  
   0.00          1.06
********************************************************************************

.
.
SELECT WTG_ROWID,ROWID
FROM
DR$WAITING  WHERE WTG_CID = :b1  AND WTG_PID = :b2


call     count       cpu    elapsed       disk    
query    current        rows
-- ---- -- ---  -- ----- -- ---- -- -- ---- --
-- ---- -- -- ---- --  -- ---- --
Parse        0      0.00       0.00          0        
0          0           0
Execute      4      0.00       0.00          0        
0          0           0
Fetch        4     29.71      29.23      85752    
118639          0           0
-- ---- -- ---  -- ----- -- ---- -- -- ---- --
-- ---- -- -- ---- --  -- ---- --
total        8     29.71      29.24      85752    
118639          0           0

Misses in library cache during parse: 0
Optimizer goal: CHOOSE
Parsing user id: 29  (CTXSYS)   (recursive depth: 2)
error during execute of EXPLAIN PLAN statement
ORA-00942 (See ORA-00942.ora-code.com): table or view does not exist

parse error offset: 101

Elapsed times include waiting on following events:
 Event waited on                             Times  
Max. Wait  Total Waited
 -- ---- ---- ---- ---- ---- ---- ---- --   Waited
-- ---- --  -- ---- ----
 db file sequential read                      4837  
   0.00          0.19
 db file scattered read                      17903  
   0.00          2.05

Here are a few details about the table:

Last Analyzed: 28-FEB-05
Freelists: 1
Blocks: 29579

The table was analyzed using
FND_STATS.GATHER_SCHEMA_STATS('CTXSYS') procedure.

There is an index on the table for the following
columns: (WTG_CID, WTG_PID, WTG_ROWID)

Any help or pointers in understanding and optimizing
will be appreciated.

Regards
Naveen



   
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