In version 8.0, postgresql's pg_size_pretty function is used
(http://www.postgresql.org/docs/9.4/static/functions-admin.html) when
getting the size of a binary field when reading if `bin_size`
or `bin_size_[col_name]` is set in the context.
So in 8.0 the size of a binary field get units bytes, kB, MB, GB and TB
which was not taken into account. e.g: '5.3 GB'.
This fix uses the size of the string to choose to differenciate the two.
e.g: '10000 bytes' (the longest size) will be returned directly, but
for something longer the human size of the content length will be
returned.
There is a corner case if a file is shorter than 12 bytes but
it is an enough of a small scenario with small implications that it is
deemed acceptable.
closes#7485
opw-644085
e33baecfa3