Honestly I don't know if it would
worth the hassle of adding conditional runtime import: probably not
for the current set of conditional features, they are just a few.
I also doubt it would be worth the hassle.
I think it would be very nice to expose the libpq-version (and quality of this information as in "asked at compile time" or "asked right now, because it is 9.1 or newer and we can do it") to the Python application: so the application programmer would be able to issue workarounds like the "bytea-encoding to escape".
best wishes,
Harald
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Harald Armin Massa
www.2ndQuadrant.comPostgreSQL Training, Services and Support