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Re: checking update/insert return

From: Bruno LEVEQUE <bruno(dot)leveque(at)net6d(dot)com>
To: "Marcus Andree S(dot) Magalhaes" <marcus(dot)magalhaes(at)vlinfo(dot)com(dot)br>
Cc: pgsql-novice(at)postgresql(dot)org
Subject: Re: checking update/insert return
Date: 2004-01-05 21:22:25
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-novice

Why do you not use the serial data type : SERIAL ?

EX. :
create table mytable (
name text);    <- or anything else

So, when you want to insert data your request becomes :
insert into mytable (name) values ($name)

And you are sure that id is unique (you do not need your loop, your 
tests, ...).


Marcus Andree S. Magalhaes wrote:

>Dear list,
>Is there any way to check a successful insertion or update on a table
>in plpgsql?
>We have a highly concurrent system here, and we want to return a valid
>and unique ID to the caller, like the following pseudo code (no flames,
>didatic use only ;-):
>while (true)
> found = select count (*) from mytable where id = $id
> if (found == 0) /* non existent id */
>     insert into mytable (id. name) values ($id, $name)
>     /* someone in parallel could have inserted the same id before
>        so we need to check if this insertion was OK, but how??? */
>     if (INSERTED) return $id /* we inserted our id with success */
>     else $id = $id + 1 /* someone has used this id, increment it
>                           and try again */
>     end if
> else
>     $id = $id + 1 /*id already exists*/
> end if
>end while
>My question is, is there any postgres internal boolean function
>that somewhat resembles what I described here as "INSERTED" ???
>I did some research and found an internal function called FOUND, but
>it seems to work only with select.
>In short, how to determine if an insert (or update) clause has
>ended with success? The backend seems to indicate this, by a INSERT
>Any help is welcome
>---------------------------(end of broadcast)---------------------------
>TIP 6: Have you searched our list archives?

System Engineer

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Subject: Re: checking update/insert return
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