RE: Lock
- From: "Taylor, Chris David" <ChrisDavid.Taylor@xxxxxxxxxxxxxxx>
- To: "'cure@xxxxxxxxxxxxx'" <cure@xxxxxxxxxxxxx>, "'oracle-l@xxxxxxxxxxxxx'" <oracle-l@xxxxxxxxxxxxx>
- Date: Mon, 12 Mar 2012 07:01:49 -0500
Paul,
It's ONE lock that in this case will be for EVERY row in the table (since you
do not specify a WHERE statement)
Lock Type = DML
Mode Held = Row-X (SX)
Any subsequent updates/deletes from this table will "WAIT" for your update to
complete before they are allowed (inserts and selects will be unaffected).
If you specify a WHERE statement (i.e. update...where ROWNUM=1) you also get
ONE lock for ONE row: Row-X (SX). Other updates on other rows will continue to
process.
I think Row-X (SX) lock can be 1:1 or 1:M though that may not be technically
correct.
If you specify a where statement to only update a subset of rows
Chris Taylor
"Quality is never an accident; it is always the result of intelligent effort."
-- John Ruskin (English Writer 1819-1900)
Any views and/or opinions expressed herein are my own and do not necessarily
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employees.
-----Original Message-----
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On
Behalf Of Paul Harrison
Sent: Saturday, March 10, 2012 10:57 AM
To: oracle-l@xxxxxxxxxxxxx
Subject: Lock
Hello,
I have a table with four rows. I issue the sql statement: update table set name
= 'test'; this will update 4 rows. Will Oracle create 4 locks one for each row
or 1 lock for the 4 rows?
Thanks,
Paul
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