11g oracle lock question

Question

I'm trying to understand locking on "other end of FK", i..e. operations on child table in 11g. Database version 11.2.0.2.0
Table bal_fct has columns(branch id, acct id, cust id, bal dt, bal ccy id, stmt id, bal amt). PK/Unique index on branch id, acct id, cust id, bal dt, bal ccy id, stmt id in that order. All these columns have FKs. No index on these FKs. There is a bitmap index on acct_id.
An ETL job is doing inserts in bal fct table (child). As I understand, any operation on child table would take RX(mode 3) on parent tables in 11g.
I queried locks taken. It is taking mode 3 lock on all the dimension tables EXCEPT ACCT(acct_id). Why? I assumed that it will take also mode 3 lock on ACCT also. I have read in other threads that bitmap index really don't count in these discussions.
Thanks for your help.
Edited by: rkuppa on May 26, 2013 7:10 AM
Edited by: rkuppa on May 26, 2013 7:11 AM
Edited by: rkuppa on May 26, 2013 4:23 PM

Answer 1

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I'm trying to understand locking on "other end of FK", i..e. operations on child table in 11g. Database version 11.2.0.2.0
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Here are two articles about that by Jonathan Lewis
http://jonathanlewis.wordpress.com/2010/06/21/locks/
http://jonathanlewis.wordpress.com/2010/02/15/lock-horror/
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Table bal_fct has columns(branch id, acct id, cust id, bal dt, bal ccy id, stmt id, bal amt). PK/Unique index on branch id, acct id, cust id, bal dt, bal ccy id, stmt id in that order. All these columns have FKs. No index on these FKs. There is a bitmap index on acct_id.
An ETL job is doing inserts in bal fct table (child). As I understand, any operation on child table would take RX(mode 3) on parent tables in 11g.
I queried locks taken. It is taking mode 3 lock on all the tables EXCEPT ACCT(acct_id). Why? I assumed that it will take also mode 3 lock on ACCT also. I have read in other threads that bitmap index really don't count in these discussions.
>
You won't get row level locks when a bitmap index is used.
Can you edit your post and clarify it a bit.
You mention 'bal_fct table (child). The table name has 'fct' in it: is this a fact table or a child table?
And post whether your issue is similar to the one in this other thread from yesterday.
11g child table update locking
Some of the info there may help.