I think so, for the moment anyhow!
Thanks all,
John S.

Cliff Ford wrote:
Comment on Peter's suggestion: I am no expert on these things, but it is my understanding that for MySQL LAST_INSERT_ID() fetches the last autoincrement value made by the current insert, so the outcome is not affected by virtually simultaneous requests. And I don't think MySQL accepts a value for the autoincrement key. I am a bit surprised that the code you quote is reliable - surely there is a possibility of an insert after calling GetNextID and before calling SQLInsert in the python code?

Comment on Tino's suggestion: I think that LAST_INSERT_ID() is MySQL specific and I guess CURRVAL() is Postgres specific. But the principle is the same: calling within the same Z SQL Method ought to be safe.

Anyway, I hope John has had is question answered.


Tino Wildenhain wrote:

Peter Bengtsson wrote:

What if you have 1,000,000 requests/sec?
What if between the INSERT and the LAST_INSERT_ID() another INSERT is made?

I use PostgreSQL and with postgres you can always ask the sequence what
the next id is going to be. It goes something like this::

next_id = context.GetNextId()[0].next_id
context.SQLInsertUser(uid=next_id, name='Peter')

where 'GetNextId' is a ZSQL method that looks like this::

SELECT NEXTVAL('users_uid_seq') AS next_id

Its even easier:
one ZSQL Method:

INSERT INTO foo (foo_id,blah,bar) VALUES
(nextval('foo_foo_id_seq'),<dtml-sqlvar blah> ... );
SELECT CURRVAL('foo_foo_id_seq') as foo_id;

But your above solution is valid too.

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John Schinnerer - MA, Whole Systems Design
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