muk_base/muk_fields_lobject

MuK Large Objects Field

PostgreSQL offers support for large objects, which provide stream-style access to user data that is stored in a special large-object structure. They are useful with data values too large to be manipulated conveniently as a whole.

Psycopg allows access to the large object using the lobject class. Objects are generated using the connection.lobject() factory method. Data can be retrieved either as bytes or as Unicode strings.

Psycopg large object support efficient import/export with file system files using the lo_import() and lo_export() libpq functions.

Changed in version 2.6: added support for large objects greated than 2GB. Note that the support is enabled only if all the following conditions are verified:

• the Python build is 64 bits;
• the extension was built against at least libpq 9.3;
• the server version is at least PostgreSQL 9.3 (server_version must be >= 90300).

If Psycopg was built with 64 bits large objects support (i.e. the first two contidions above are verified), the psycopg2.__version__ constant will contain the lo64 flag. If any of the contition is not met several lobject methods will fail if the arguments exceed 2GB.