Re: Row and Table Locking

On Tue, 28 Aug 2001, nsouto_at_optushome.com.au.nospam wrote:

> I'm having trouble seeing how updates can be buried in ORACLE,
> Graham. Given that once a row is locked, all other updates are
> queued until lock is released by an end transaction (or
> rollback).

Yes, this is true for any update statement. Oracle will lock a row while it is actually being written to no matter what anybody else might want. But what Oracle will do for the next-in-line update process when the lock is released, is your question. This is all based on the isolation level for that session's transaction.

READ COMMITTED
Oracle will let the queued update process update its rows.

SERIALIZABLE
Oracle will tell the queued update process that it isn't allowed to update this row because it was updated during the duration of the transaction, something like "Non-serializable" error.

> Between tables maybe, but on a single table I can't see it
> happening.

I'm not sure what you meant here.

-- 
Galen Boyer
It seems to me, I remember every single thing I know.