Re: [ADMIN] Deadlock on transaction

On Mon, Feb 12, 2007 at 03:08:27PM -0300, Ezequias Rodrigues da Rocha wrote:
> I mean really deadlock. Other transactions can't access the database until
> the main transaction is complete. 

What you describe sounds like a blocking lock: one transaction uses a 
resource and another has to wait until it is not locked anymore

A deadlock is a special case: two transactions both need resources A and 
B. transaction 1 locks A, and the next moment transaction 2 locks B. Now 
transaction 1 waits for 2 to release B, but at the same time 2 waits for 1 
to release A. This is called a deadlock, or circulair lock.
Postgresql automatically detects such a situation and rolls one of them 
back. The client recieves a 'restartable database error' and that is 
exactly true: ususally another try will work. 

One method of fixing deadlocks is to make sure all your code accesses the 
database in the same order. Alphabetically is easiest to remember...

-- 
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"Nothing is as subjective as reality"
Reinoud van Leeuwen    reinoud.v@n.leeuwen.net
http://www.xs4all.nl/~reinoud
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