Re: Dropping a temporary view? - Mailing list pgsql-general

On 3/20/24 10:54 AM, Celia McInnis wrote:

Comments below more to sort out the process in my head then anything else.

Hi Adrian

The only behaviour changed for the debugging was to make the view non-temporary, so that I could verify in psql that the content of the view was what I wanted it to be. Debugging CGI software can be quite difficult, so it's always good to have debugging hooks as a part of the software - I know that I always have a DEBUG flag which, if on, prints out all kinds of stuff into a debug file, and I just had my software set a different name for DEBUG mode's non-temporary view than I was using for the temporary view, as advised by Christophe Pettus.

This indicates you are working in different sessions and therefore creating a regular view to see the same data in all sessions.

Previously this regular view was named the same as the temporary view you create in the production database.

Now you name that regular view a unique name not to conflict with the temporary view name(s).

No, unfortunately I didn't do an explain on the slow query - and it's too late now since the views are removed. However, I never had a delay when waiting for the view to be created in my web software, so, I'll just proceed being more careful and hope that the delay seen was due to some big mess I created.

In your original post you say the delay occurred on a SELECT not a CREATE VIEW after:

"DROP VIEW tempview;
DROP VIEW

postgresql did that successfully, but when I then did

select * from tempview:

"

Where the select would have been on the regular view named tempview.

Thanks,

Celia McInnis

On Wed, Mar 20, 2024 at 1:01 PM Adrian Klaver <adrian.klaver@aklaver.com> wrote:

On 3/20/24 09:51, Celia McInnis wrote:
> The view is being used in some web query software that multiple people
> will be accessing and the contents of the view depend on what the person
> is querying, so I think that temporary views or tables are a good idea.
> I change to non-temporary views or tables (in a test version of the
> software which is not web-crawl-able) when I'm trying to debug things,
> and I guess I have to be careful to clean those up when I switch back to
> the temporary tables/views.

Why change behavior for the tests? Seems that sort of negates the value
of the testing.

Have you run EXPLAIN ANALYZE on the problem query?


>
>
>
> On Wed, Mar 20, 2024 at 11:46 AM Adrian Klaver
> <adrian.klaver@aklaver.com <mailto:adrian.klaver@aklaver.com>> wrote:
>
>     On 3/20/24 08:39, Celia McInnis wrote:
>      > Ok, thanks - so I guess that means that if there is both a
>     temporary and
>      > a non temporary view called "tempvie",
>      >
>      > DROP VIEW tempview;
>      >
>      > will remove the 1st tempview found, which with my path is the
>     temporary
>      > one. Is there some reason why it then took 7 minutes to select
>     from the
>      > non-temporary view tempview after I dropped the temporary view
>     tempview?
>      >
>      > I have sometimes had some very long query times when running query
>      > software, and maybe they are resulting from my switching between
>      > temporary and non-temporary views of the same name while
>     debugging. If
>      > so, is there something I should be doing to clean up any temporary
>      > messes I am creating?
>
>     What is the purpose of the temp view over the the regular view process?
>
>     How do they differ in data?
>
>     Is all the above happening in one session?
>
>     Have you run EXPLAIN ANALYZE on the select from the regular view?
>
>      >
>      > Thanks,
>      > Celia McInnis
>      >
>
>
>     --
>     Adrian Klaver
>     adrian.klaver@aklaver.com <mailto:adrian.klaver@aklaver.com>
>

--
Adrian Klaver
adrian.klaver@aklaver.com

-- 
Adrian Klaver
adrian.klaver@aklaver.com