My situation is that I am interacting PHP 4.1.2 to PostgreSQL 7.2.2
I have no difficulty inserting and managing BLOBs into the Large Object
system table, and I have a user table called images which maintains the
relationship between the BLOB loid and the identity that relates to it in
my user tables. So far so good.
When I RTFM obout psql it refers to the \lo_import, \lo_list, \lo_export
and \lo_unlink functions.
The syntax for the \lo_import function indicates that a comment may be
appended to the BLOB entry in the large object system table. What is not
mentioned is that this will only occur if psql is run as the PostgreSQL
superuser.
Now, my concern is that if I use pg_dump with the --clean or --create, and
the --blobs options, and then try a pg_restore from the resulting archive
file, I believe the BLOBs will take up a different loid to the one they
came from, and hence the relation in my user table will be broken and I
will not be able to relocate the BLOBs using my identifier in my images
table.
My other problem is that the various functions in PHP, namely the various
pg_lo_* functions do not appear to have the ability to include the comment
option that is available to \lo_import under psql.
I suppose one workaround, though not very elegant, would be to use under
PHP something like `psql \lo_export <known_file_name>` whilst running
through the records in the images table, and not to use the --blobs option
under pg_dump, then use `psql \lo_import <known_file_name>` called from
PHP to reload them after a pg_restore has been run, at the same time
updating the loids in my images table. As I say very inelegant.
I guess this must be a shortfall in both PHP, in as much as it doesn't
appear to handle BLOBs to cleanly, and PostgreSQL in its way that it
handles the description column in the large opjects system table.
Am I right or wrong, or is there a better workaround?
--
Howard.
LANNet Computing Associates - Your Linux people <http://www.lannetlinux.com>
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