.TH MDB_COPY 1 "2017/07/31" "LMDB 0.9.70"
.\" Copyright 2012-2020 Howard Chu, Symas Corp. All Rights Reserved.
.\" Copying restrictions apply.  See COPYRIGHT/LICENSE.
.SH NAME
mdb_copy \- LMDB environment copy tool
.SH SYNOPSIS
.B mdb_copy
[\c
.BR \-V ]
[\c
.BR \-c ]
[\c
.BR \-n ]
[\c
.BR \-v ]
.B srcpath
[\c
.BR dstpath ]
.SH DESCRIPTION
The
.B mdb_copy
utility copies an LMDB environment. The environment can
be copied regardless of whether it is currently in use.
No lockfile is created, since it gets recreated at need.

If
.I dstpath
is specified it must be the path of an empty directory
for storing the backup. Otherwise, the backup will be
written to stdout.

.SH OPTIONS
.TP
.BR \-V
Write the library version number to the standard output, and exit.
.TP
.BR \-c
Compact while copying. Only current data pages will be copied; freed
or unused pages will be omitted from the copy. This option will
slow down the backup process as it is more CPU-intensive.
Currently it fails if the environment has suffered a page leak.
.TP
.BR \-n
Open LDMB environment(s) which do not use subdirectories.
.TP
.BR \-v
Use the previous environment state instead of the latest state.
This may be useful if the latest state has been corrupted.

.SH DIAGNOSTICS
Exit status is zero if no errors occur.
Errors result in a non-zero exit status and
a diagnostic message being written to standard error.
.SH CAVEATS
This utility can trigger significant file size growth if run
in parallel with write transactions, because pages which they
free during copying cannot be reused until the copy is done.
.SH "SEE ALSO"
.BR mdb_stat (1)
.SH AUTHOR
Howard Chu of Symas Corporation <http://www.symas.com>