Re: unique sequences - Mailing list pgsql-sql

From K Parker
Subject Re: unique sequences
Date
Msg-id LJEBLKFCBIGCGAAA@shared1-mail.whowhere.com
Whole thread Raw
List pgsql-sql
> Rather, each time you wish to do an insert,
> query the existing data to see what the
> maximum value is existing in the database.
> Add 1 to that and use this as your new value.
> This is guaranteed to not have any holes in
> the sequence.

True, but alas it _doesn't_ guarantee uniqueness, since there's nothing to prohibit 2 or more back ends getting the
samemax() at the
 
same time...

Thinking off the top of my head, I'm not sure you can apply FOR UPDATE to an aggregate function, so there's probably no
solutionthere, either.
 



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