How to use lobject function in psycopg2

Question

I am trying to insert Large Binary data into postgresql using psycopg2. I understand bytea datatype is more common to use but testing BLOB for any future use cases.

Versions of postgresql and psycopg2 is below.

pip list | grep psycopg2
psycopg2 (2.5.1)

rpm -qa | grep postgres
postgresql-server-9.2.15-1.el7_2.x86_64

I use python 2.7.5

python -V
Python 2.7.5

Below is my code snippet

file = "/home/test/jefferson_love_memorial_514993.jpg"
with open(file,"r") as fd:
  try:
    # First connect to postgresql server
    conn = psycopg2.connect("dbname='sample' user='sample' host='10.1.0.19' password='sample'")

    # Initate the session with postgresql to write large object instance
    lobj = conn.lobject(0,'r',0)

    # Write the data to database
    lobj.write(fd.read())

  except (psycopg2.Warning, psycopg2.Error) as e:
    print "Exception: {}".format(e)

However, after I execute the code I get no error but nothing is inserted into the table.

-bash-4.2$ psql -d sample
psql (9.2.15)
Type "help" for help.

sample=# SELECT * FROM pg_largeobject_metadata;
 lomowner | lomacl
----------+--------
(0 rows)

sample=# SELECT * FROM pg_largeobject;
 loid | pageno | data
------+--------+------
(0 rows)

May I ask what is lacking in my code?

Answer 1

I found the reason.

I have forgotten to do conn.commit() after lobj.write(). After doing commit it works perfectly.