Re: large object write performance

[Bram Van Steenlandt <bram@xxxxxxxxxxx>]

Op 08-10-15 om 14:10 schreef Graeme B. Bell:

On 08 Oct 2015, at 13:50, Bram Van Steenlandt <bram@xxxxxxxxxxx> wrote:

1. The part is "fobj = lobject(db.db,0,"r",0,fpath)", I don't think there is anything there

Re: lobject

http://initd.org/psycopg/docs/usage.html#large-objects

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

See *

I was under the impression they meant that the lobject was using lo_import and lo_export.
I can't seem to find how to use lo_import en export, I searched google and came to the conclusion the lobject was the way to go.
>>> x.lo_import()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'psycopg2._psycopg.connection' object has no attribute 'lo_import'

>>> from psycopg2.extensions import lo_importTraceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: cannot import name lo_import

Also:
http://initd.org/psycopg/docs/connection.html

lobject([oid[, mode[, new_oid[, new_file[, lobject_factory]]]]])

Return a new database large object as a lobject instance.

See Access to PostgreSQL large objects for an overview.

Parameters:

oid – The OID of the object to read or write. 0 to create a new large object and and have its OID assigned automatically. mode – Access mode to the object, see below. new_oid – Create a new object using the specified OID. The function raises OperationalError if the OID is already in use. Default is 0, meaning assign a new one automatically. new_file – The name of a file to be imported in the the database (using the lo_import() function) lobject_factory – Subclass of lobject to be instantiated.

lobject seems to default to string handling in Python
That’s going to be slow.
Try using lo_import / export?

Graeme Bell