Tom Lane wrote:
Andrew Dunstan <[EMAIL PROTECTED]> writes:
Bruce Momjian wrote:
Also, Andrew, on your other patch for log_session_info line, Magnus had
the idea of giving each session an id based on the first transaction of
the session.
I did think about using a cluster-wide sequence, if we can make such a thing (might also be useful for system generated UIDs too).
Not a good idea IMHO. If you do that, then there will be no such thing as a purely read-only transaction, because *every* transaction will include a nextval() call. That means even read-only transactions cannot commit till the disk spins.
If we want a unique id for transient purposes like logging, then make some kind of counter in shared memory. Don't use a sequence, it's much too heavyweight.
I'm not sure I understand. I didn't suggest that a sequence should be used for txn ids. For the purpose I had in mind we would call nextval() once per connection, and, for the other purpose where I suggested it would be useful, once per "create user". That doesn't seem very heavyweight.
cheers
andrew
---------------------------(end of broadcast)--------------------------- TIP 4: Don't 'kill -9' the postmaster
