| From: | Peter Eisentraut <peter_e(at)gmx(dot)net> |
|---|---|
| To: | MaRcElO PeReIrA <gandalf_mp(at)yahoo(dot)com(dot)br> |
| Cc: | pgsql-general(at)postgresql(dot)org |
| Subject: | Re: Sequences without blank holes |
| Date: | 2003-11-06 08:58:41 |
| Message-ID: | Pine.LNX.4.44.0311060956080.9763-100000@peter.localdomain |
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| Lists: | pgsql-general |
MaRcElO PeReIrA writes:
> How can I assure a ''sequence WITHOUT holes''?
> $ SELECT max(prod_id)+1 FROM products;
You can do that, but
SELECT prod_id FROM products ORDER BY prod_id DESC LIMIT 1;
will be faster. In fact, if you have a B-tree index on prod_id (which you
should), it will be nearly constant time.
Also, make sure if you do a SELECT, then some client application logic,
then an UPDATE, to do it in one transaction and use the appropriate
isolation level, locking, etc.
--
Peter Eisentraut peter_e(at)gmx(dot)net
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