RE: query and delete records really slow in a table

  • From: "Koppelaars, Toon" <T.Koppelaars@xxxxxxxxxxxxxxxxxxxx>
  • To: <legedoos@xxxxxxxxx>, <oracle-l@xxxxxxxxxxxxx>
  • Date: Fri, 19 Oct 2007 15:06:08 +0200

Rob,

- Can you share the delete statement text?
- Is the index structure on all involved foreign keys the same (on this
and the other database)?
- Can perform a sql-trace of both cases (fast and slow)?

Toon

-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx
[mailto:oracle-l-bounce@xxxxxxxxxxxxx] On Behalf Of LegeDoos
Sent: vrijdag 19 oktober 2007 14:29
To: oracle-l@xxxxxxxxxxxxx
Subject: query and delete records really slow in a table

Hi there!

We have a couple (18) of tables "linked" with foreign keys and
cascading delete. The largest table contains < 1.000.000 records.

When deleting a record from the top level table, this is extremely
slow (like waiting a couple of minutes). On another database (on the
same server and on another server) deleting is fast (<1sec). Tables
contain defferent data.

-There are no blocking locks
-rebuilding the indexes didn't help
-the explain plan looks ok and is the same for the different databases

0               DELETE STATEMENT optimizer=ALL_ROWS (cost=460 card=1
bytes=73)       
1       0         DELETE of 'OST_STUDENT_STUDIEVOORTGANG'       
2       1           HASH JOIN (SEMI) (cost=460 card=1 bytes=73) 
3       2             TABLE ACCESS (FULL) of
'OST_STUDENT_STUDIEVOORTGANG' TABLE
(cost=57 card=31859 bytes=1146924)
4       2             TABLE ACCESS (FULL) of 'OST_STUDENT_EXAMEN' TABLE
(cost=199
card=55431 bytes=2050947)

-I moved all tables en indexes to another tablespace, didn't help
-There are no errors in the alert.log.

Can anybody help?

Thanks!

Rob
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