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F.41. vacuumlo

vacuumlo is a simple utility program that will remove any "orphaned" large objects from a PostgreSQL database. An orphaned large object (LO) is considered to be any LO whose OID does not appear in any oid or lo data column of the database.

If you use this, you may also be interested in the lo_manage trigger in contrib/lo (see Section F.17). lo_manage is useful to try to avoid creating orphaned LOs in the first place.

F.41.1. Usage

vacuumlo [options] database [database2 ... databaseN]

All databases named on the command line are processed. Available options include:

-v

Write a lot of progress messages.

-n

Don't remove anything, just show what would be done.

-l limit

Remove no more than limit large objects per transaction (default 1000). Since the server acquires a lock per LO removed, removing too many LOs in one transaction risks exceeding max_locks_per_transaction. Set the limit to zero if you want all removals done in a single transaction.

-U username

User name to connect as.

-w
--no-password

Never issue a password prompt. If the server requires password authentication and a password is not available by other means such as a .pgpass file, the connection attempt will fail. This option can be useful in batch jobs and scripts where no user is present to enter a password.

-W

Force vacuumlo to prompt for a password before connecting to a database.

This option is never essential, since vacuumlo will automatically prompt for a password if the server demands password authentication. However, vacuumlo will waste a connection attempt finding out that the server wants a password. In some cases it is worth typing -W to avoid the extra connection attempt.

-h hostname

Database server's host.

-p port

Database server's port.

F.41.2. Method

First, vacuumlo builds a temporary table which contains all of the OIDs of the large objects in the selected database.

It then scans through all columns in the database that are of type oid or lo, and removes matching entries from the temporary table. (Note: only types with these names are considered; in particular, domains over them are not considered.)

The remaining entries in the temporary table identify orphaned LOs. These are removed.

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