Subject: Re: psycopg3, prepared statements
To: Daniele Varrazzo <daniele.varrazzo@gmail.com>,
 Vladimir Ryabtsev <greatvovan@gmail.com>
Cc: psycopg@postgresql.org
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From: Adrian Klaver <adrian.klaver@aklaver.com>
Message-ID: <c07974b0-471b-340d-ee6e-1a145fbd8999@aklaver.com>
Date: Wed, 23 Dec 2020 15:12:36 -0800
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On 12/23/20 2:53 PM, Daniele Varrazzo wrote:
> On Tue, 22 Dec 2020 at 22:36, Daniele Varrazzo
> <daniele.varrazzo@gmail.com> wrote:
>>
>> On Tue, 22 Dec 2020 at 05:39, Vladimir Ryabtsev <greatvovan@gmail.com> wrote:
> 

> 
> Heads up about this: it's better than I thought!
> 
> I wrote a first implementation of the prepared statements cache using
> the query as a key, but it's actually enough to use the (query, types)
> tuple in order to tell apart statements that are executed with
> different types. This way even the "SELECT %s" case won't be a
> problem. Of course a statement executed with a mix of types will be
> prepared later than `prepare_threshold`, but I think it's perfectly

Alright I was following you until you got to above. I'm not following 
why it would overshoot prepare_threshold?

> acceptable: the case doesn't happen often and having the query
> prepared after 10 times instead of 5 doesn't change much if it will be
> executed hundreds of times or more.
> 
> What seems a feature-complete branch is available in [1]. The tests
> [2] illustrate the main behaviour of the prepared statements system.
> 
> [1]: https://github.com/psycopg/psycopg3/tree/prepared-statements>.
> [2]: https://github.com/psycopg/psycopg3/blob/prepared-statements/tests/test_prepared.py
> 
> Off to do some benchmarks now...
> 
> -- Daniele
> 


-- 
Adrian Klaver
adrian.klaver@aklaver.com