"Christopher Kings-Lynne" <[EMAIL PROTECTED]> writes:
>> Uh, why exactly do you think this is race-free?
> How about:
> INSERT INTO table SELECT 1, 'foo' WHERE NOT EXISTS (SELECT TRUE FROM table
> WHERE pkcol=1 FOR UPDATE);
> It's a lot more straightforward and has a FOR UPDATE. Can this still
> Uh, why exactly do you think this is race-free?
>
> It looks fancy, but AFAICS the SELECT will return info that is correct
> as of its starting timestamp; which is not enough to guarantee that the
> INSERT won't conflict with another transaction doing the same thing
> concurrently.
How about:
"Christopher Kings-Lynne" <[EMAIL PROTECTED]> writes:
> INSERT INTO table SELECT 1, 'foo' EXCEPT SELECT 1, 'foo' FROM table WHERE
> pkcol=1;
> See? So now that INSERT statement will insert the row if it doesn't exist,
> or insert zero rows if it does. You are then guaranteed that your
> transacti
