In SQLite it's possible to define columns using type names such as
"smallint unsigned" or "short integer", without any changes to the way
those data types are handled, given its "dynamic typing" features.
Improve the pgloader casting machinery for SQLite to handle those cases.
When using SQLite 3, a blob column might return either string of byte
vector values dynamically depending on the data itself, or maybe some
more complex parameters controlled at data insert time.
Hard-code the rule that a blob column returned as a string is in fact
base64 encoded (which looks like common practice) and decode it
automatically when needed, before sending to byte-vector-to-bytea. It
might be a tad slow but at least the data is properly converted.
In future, that decision might come and byte us in the back again, at
which point it'll be necessary to consider full casting options as in
the MySQL CAST rules. It seems like a big enough win for now if we can
avoid that.
This issue has been re-opened with blob instead of double. Semi-blindly
implement support for the blob type with an image data type.
Disturbingly enough when tested with non-binary data SQLite was
returning strings rather than byte vectors, tripping up the transform
function that sure expects byte vectors.
