Re: Atomicity?

Naz Gassiep wrote:
> I am getting an error that I think I understand, but that I didn't think
> should happen.
>
> Below is the output from psql that I am getting to trigger this error.
> If the violation of the constraint really is being caused WITHIN the
> query, doesn't that violate the principle of atomicity? I.e., operations
> and entities should be considered a single entire construct rather than
> a collection of smaller, discrete parts. Or do I have my understanding
> all wrong?
>
> In any case, how do I get around this problem?

If you do not specify the beginning of a transaction, all statements are
run within their own transaction.. e;g:

Your example actually means:

begin;

> conwatch=# UPDATE replies SET rgt = rgt + 2 WHERE postid = 18 AND rgt >=
> 11;

commit;

begin;
> conwatch=# UPDATE replies SET rgt = rgt + 2 WHERE postid = 18 AND rgt = 14;
commit;

What you want is:

begin;

> UPDATE 1
> conwatch=# UPDATE replies SET rgt = rgt + 2 WHERE postid = 18 AND rgt = 13;
> UPDATE 1
> conwatch=# UPDATE replies SET rgt = rgt + 2 WHERE postid = 18 AND rgt = 12;
> UPDATE 1
> conwatch=# UPDATE replies SET rgt = rgt + 2 WHERE postid = 18 AND rgt = 11;
> UPDATE 1
> conwatch=#

commit;

Joshua D. Drake


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