.\" This is -*-nroff-*-
.\" XXX standard disclaimer belongs here....
.\" $Header: /data/01/postgres/src/ref/unix/RCS/vacuum.1src,v 1.2 1993/01/26 02:43:13 aoki Exp $
.TH VACUUM UNIX 01/23/93
.XA 1 Vacuum
.SH NAME
vacuum \(em vacuum a database
.SH SYNOPSIS
.BR vacuum
[\c
.BR -a
system]
[\c
.BR -h
host]
[\c
.BR -p
port]
[dbname]
.SH DESCRIPTION
.BR Vacuum
vacuums a POSTGRES database.
Vacuuming a database moves deleted records to an archive
(for archived classes; see 
.IR create (commands)),
cleans out records from aborted transactions, and updates statistics
that are stored in the system catalogs and used by the query
optimizer.  Databases should be vacuumed periodically, if for no other
reason than to update the statistics (which make the system run more
efficiently).  We recommend using using a mechanism such as
.IR "cron" (1)
or 
.IR "at" (1)
to vacuum production databases on a nightly basis.
.PP
.IR Vacuum
is a shell script that invokes
.IR monitor .
Hence, a
.IR postmaster
process must be running on the database server host before
.IR vacuum 
is executed.  In addition, the 
.SM PGOPTION
and
.SM PGREALM
environment variables will be passed on to
.IR monitor
and processed as described in 
.IR monitor (unix).
.PP
The optional argument
.IR dbname
specifies the name of the database to be vacuumed.
.IR Dbname
defaults to the value of the 
.SM USER
environment variable.
.PP
.IR Vacuum
understands the following command-line options:
.TP 5n
.BR "-a" " system"
Specifies an authentication system 
.IR "system"
(see 
.IR introduction (unix))
to use in connecting to the 
.IR postmaster
process.  The default is site-specific.
.TP
.BR "-h" " host"
Specifies the hostname of the machine on which the 
.IR postmaster
is running.  Defaults to the name of the local host, or the value of
the
.SM PGHOST
environment variable (if set).
.TP
.BR "-p" " port"
Specifies the Internet TCP port on which the
.IR postmaster
is listening for connections.  Defaults to 4321, or the value of the
.SM PGPORT
environment variable (if set).
.SH "SEE ALSO"
monitor(unix),
postmaster(unix),
vacuum(commands).
.SH DIAGNOSTICS
.TP 5n
.BI "Error: Failed to connect to backend (host=" "xxx" ", port=" "xxx" ")"
.IR Vacuum
could not attach to the 
.IR postmaster 
process on the specified host and port.  If you see this message,
ensure that the
.IR postmaster
is running on the proper host and that you have specified the proper
port.  If your site uses an authentication system, ensure that you
have obtained the required authentication credentials.
.TP
.BI "user \*(lq" "username" "\*(rq is not in \*(lqpg_user\*(rq"
You do not have a valid entry in the relation \*(lqpg_user\*(rq and
cannot do anything with \*(PG at all; contact your \*(PG site
administrator.