pg_lo_open() opens a large object in the database
and returns large object resource so that it can be manipulated.
Warning
Do not close the database connection before closing the large
object resource.
To use the large object interface, it is necessary to
enclose it within a transaction block.
Note:
This function used to be called pg_loopen().
Parameters
connection
PostgreSQL database connection resource. When
connection
is not present, the default connection
is used. The default connection is the last connection made by
pg_connect() or pg_pconnect().
oid
The OID of the large object in the database.
mode
Can be either "r" for read-only, "w" for write only or "rw" for read and
write.