vacuumlo — remove orphaned large objects from a LightDB database
vacuumlo [option...] dbname...
vacuumlo is a simple utility program that will remove any
“orphaned” large objects from a
LightDB 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 the lo module.
lo_manage is useful to try
to avoid creating orphaned LOs in the first place.
All databases named on the command line are processed.
vacuumlo accepts the following command-line arguments:
-l limit--limit=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.
-n--dry-runDon't remove anything, just show what would be done.
-v--verboseWrite a lot of progress messages.
-V--versionPrint the vacuumlo version and exit.
-?--helpShow help about vacuumlo command line arguments, and exit.
vacuumlo also accepts the following command-line arguments for connection parameters:
-h host--host=hostDatabase server's host.
-p port--port=portDatabase server's port.
-U username--username=usernameUser 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--passwordForce 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.
LTHOSTLTPORTLTUSERDefault connection parameters.
This utility, like most other LightDB utilities, also uses the environment variables supported by libpq (see Section 32.14).
The environment variable LT_COLOR specifies whether to use
color in diagnostic messages. Possible values are
always, auto and
never.
vacuumlo works by the following 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.
Peter Mount <peter@retep.org.uk>