Re: Driver Module

Hi

On Wed, Jan 11, 2017 at 10:24 PM, George Gelashvili
<ggelashvili(at)pivotal(dot)io> wrote:
> Hi Dave,
>
> Thanks for the pointer.
> We realized that many of the changes we would need to make for supporting
> Greenplum would need to go where there is pg version checking throughout the
> code. This is because unlike PPAS which mostly adds additional features,
> Greenplum is based on postgres 8.3.

Isn't Heikki fixing that for your next release?

> It looks like much of the version checking logic is repeated at points where
> the features are differentiated by postgres version.
>
> It might make sense at this point to refactor the way that feature flagging
> is done to be a little bit more unified between server types and postgres
> versions so that we could for example have logic along the lines of:
>
> feature_enablement = FeatureEnablement(postgres_flavor, postgres_version)
>
> #...
>
> if(feature_enablement.check_internal_triggers ):
> # feature call here
>
> and then in a feature enablement class, reference the various versions and
> flavors of postgres.
>
> Any thoughts on this?

I worry that the list of features would end up being huge - we're not
just talking about basic things like whether DDL triggers are
supported, but the catalog schema (e.g. procpid vs. pid in
pg_stat_activity) and small things like whether a particular GUC can
be set on a tablespace.

Ultimately, you have to do a version check at some point though
(unless you're proposing to do something similar to probing the DOM in
a browser at runtime). Doesn't GP's version string contain additional
info beyond '8.3'? In pgAdmin 3 we had a EdbMinimumVersion(int major,
int minor) function in the connection class that basically did:

return isEdb && BackendMinimumVersion(x, y);

Something like that could check other elements of the GP version number.

--
Dave Page
Blog: http://pgsnake.blogspot.com
Twitter: @pgsnake

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