From: Richard Huxton <dev@archonet.com>
To: Andreas Tille <tillea@rki.de>
To: PostgreSQL SQL <pgsql-sql@postgresql.org>
Subject: Re: Explicite typecasting of functions
Date: Wed, 14 Aug 2002 12:10:29 +0100
Message-ID: <200208141210.29995.dev@archonet.com> (raw)
In-Reply-To: <Pine.LNX.4.44.0208141123010.8253-100000@wr-linux02.rki.ivbb.bund.de>
References: <Pine.LNX.4.44.0208141123010.8253-100000@wr-linux02.rki.ivbb.bund.de>
On Wednesday 14 Aug 2002 10:30 am, Andreas Tille wrote:
> Hello,
>
> I want to insert new data into a table with increasing data set ids.
> The table has two separate "regions" of data: Those with Ids below
> 1000000 and other. If I want to create a new Id in the "lower region"
> I tried the following (simplified example):
>
>
> CREATE TABLE Items (
> Id int DEFAULT NextItem()
> CREATE FUNCTION NextItem() RETURNS INT4
> AS 'select max(Id)+1 from Items where Id < 1000000;'
> LANGUAGE 'sql';
> ERROR: Relation "items" does not exist
>
> Any hint to solve this kind of chicken-egg-problem?
Your solution is not safe anyway - you could end up with two processes trying
to insert the next value.
Can I suggest two sequences: item_low_seq and item_high_seq? Set the initial
value of each to 1,000,000 and 99,000,000 (or whatever) and then use
whichever sequence is appropriate.
In the example above you'd want something like:
id int not null default nextval('item_low_seq')
- Richard Huxton
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To: pgsql-sql@postgresql.org
Cc: dev@archonet.com, tillea@rki.de
Subject: Re: Explicite typecasting of functions
In-Reply-To: <200208141210.29995.dev@archonet.com>
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