Artem Tomyuk <admin@leboutique.com> writes:
> Trying to upgrade from 9.1 to 9.4
> Upgrade fails with error:
> Could not load library "$libdir/dblink"
> ERROR: could not load library "/usr/pgsql-9.4/lib/dblink.so":
> /usr/pgsql-9.4/lib/dblink.so: undefined symbol: PQsetSingleRowMode
dblink.so is apparently trying to link to the 9.1 version of libpq.so,
which lacks some functions that exist in 9.4. You probably need to
install the 9.4 libpq.so library first (it should work with 9.1 callers,
unlike vice versa).
regards, tom lane
