Re: Slowness of extended protocol

On 11 August 2016 at 10:18, Shay Rojansky <roji(at)roji(dot)org> wrote:

>
>
> On Thu, Aug 11, 2016 at 1:22 PM, Vladimir Sitnikov <
> sitnikov(dot)vladimir(at)gmail(dot)com> wrote:
>
> 2) The driver can use safepoints and autorollback to the good "right
>> before failure" state in case of a known failure. Here's the
>> implementation: https://github.com/pgjdbc/pgjdbc/pull/477
>>
> As far as I can remember, performance overheads are close to zero (no
>> extra roundtrips to create a safepoint)
>>
>
> What? Do you mean you do implicit savepoints and autorollback too? How
> does the driver decide when to do a savepoint? Is it on every single
> command? If not, commands can get lost when an error is raised and you
> automatically roll back? If you do a savepoint on every single command,
> that surely would impact performance even without extra roundtrips...?
>
> You seem to have a very "unique" idea of what a database driver should do
> under-the-hood for its users. At the very least I can say that your concept
> is very far from almost any database driver I've seen up to now (PostgreSQL
> JDBC, psycopg, Npgsql, libpq...). I'm not aware of other drivers that
> implicitly prepare statements, and definitely of no drivers that internally
> create savepoints and roll the back without explicit user APIs. At the very
> least you should be aware (and also clearly admit!) that you're doing
> something very different - not necessarily wrong - and not attempt to
> impose your ideas on everyone as if it's the only true way to write a db
> driver.
>

A number of other drivers default to this behaviour, including at least
MS-SQL and Oracle. psqlODBC also supports this behaviour with statement
rollback mode. And obviously PostgreSQL JDBC which Vladimir is referring to.

Dave Cramer

davec(at)postgresintl(dot)com
www.postgresintl.com