NAME¶
mongooplog - MongoDB
New in version 2.2.
SYNOPSIS¶
mongooplog is a simple tool that polls operations from the
replication oplog of a remote server, and applies them to the
local server. This capability supports certain classes of real-time migrations
that require that the source server remain online and in operation throughout
the migration process.
Typically this command will take the following form:
mongooplog --from mongodb0.example.net --host mongodb1.example.net
This command copies oplog entries from the
mongod instance running on the
host
mongodb0.example.net and duplicates operations to the host
mongodb1.example.net. If you do not need to keep the
--from host
running during the migration, consider using
mongodump and
mongorestore or another
backup operation, which may be better
suited to your operation.
- Note
- If the mongod instance specified by the
--from argument is running with authentication, then
mongooplog will not be able to copy oplog entries.
- See also
-
mongodump, mongorestore, "
/administration/backups", " Oplog Internals
Overview", and " Replica Set Oplog Sizing".
OPTIONS¶
- --help
- Returns a basic help and usage text.
- --verbose, -v
- Increases the amount of internal reporting returned on the
command line. Increase the verbosity with the -v form by including
the option multiple times, (e.g. -vvvvv.)
- --version
- Returns the version of the mongooplog utility.
- --host <hostname><:port>, -h
- Specifies a resolvable hostname for the mongod
instance to which mongooplog will apply oplog operations
retrieved from the serve specified by the --from option.
mongooplog assumes that all target mongod instances are
accessible by way of port 27017. You may, optionally, declare an
alternate port number as part of the hostname argument.
You can always connect directly to a single mongod instance by
specifying the host and port number directly.
To connect to a replica set, you can specify the replica set seed name, and
a seed list of set members, in the following format:
<replica_set_name>/<hostname1><:port>,<hostname2:<port>,...
- --port
- Specifies the port number of the mongod instance
where mongooplog will apply oplog entries. Only specify this
option if the MongoDB instance that you wish to connect to is not running
on the standard port. (i.e. 27017) You may also specify a port
number using the --host command.
- --ipv6
- Enables IPv6 support that allows mongooplog to
connect to the MongoDB instance using an IPv6 network. All MongoDB
programs and processes, including mongooplog, disable IPv6 support
by default.
- --ssl
- New in version 2.4: MongoDB added support for SSL
connections to mongod instances in mongooplog.
- Note
- SSL support in mongooplog is not compiled into the default
distribution of MongoDB. See /administration/ssl for more
information on SSL and MongoDB.
Additionally, mongooplog does not support connections to mongod
instances that require client certificate validation.
Allows
mongooplog to connect to
mongod instance over an SSL
connection.
- --username <username>, -u
<username>
- Specifies a username to authenticate to the MongoDB
instance, if your database requires authentication. Use in conjunction
with the --password option to supply a password.
- --password <password>, -p
<password>
- Specifies a password to authenticate to the MongoDB
instance. Use in conjunction with the --username option to supply a
username.
If you specify a --username without the --password option,
mongooplog will prompt for a password interactively.
- --authenticationDatabase <dbname>
- New in version 2.4.
Specifies the database that holds the user's (e.g --username)
credentials.
By default, mongooplog assumes that the database specified to the
--db argument holds the user's credentials, unless you specify
--authenticationDatabase.
See userSource, /reference/privilege-documents and
/reference/user-privileges for more information about delegated
authentication in MongoDB.
- --authenticationMechanism <name>
- New in version 2.4.
Specifies the authentication mechanism. By default, the authentication
mechanism is MONGODB-CR, which is the MongoDB challenge/response
authentication mechanism. In the MongoDB Subscriber Edition,
mongooplog also includes support for GSSAPI to handle
Kerberos authentication.
See /tutorial/control-access-to-mongodb-with-kerberos-authentication
for more information about Kerberos authentication.
- --dbpath <path>
- Specifies a directory, containing MongoDB data files, to
which mongooplog will apply operations from the oplog of the
database specified with the --from option. When used, the
--dbpath option enables mongo to attach directly to local
data files and write data without a running mongod instance. To run
with --dbpath, mongooplog needs to restrict access to the
data directory: as a result, no mongod can be access the same path
while the process runs.
- --directoryperdb
- Use the --directoryperdb in conjunction with the
corresponding option to mongod. This option allows
mongooplog to write to data files organized with each database
located in a distinct directory. This option is only relevant when
specifying the --dbpath option.
- --journal
- Allows mongooplog operations to use the durability
journal to ensure that the data files will remain in a consistent
state during the writing process. This option is only relevant when
specifying the --dbpath option.
- --fields [field1[,field2]], -f
[field1[,field2]]
- Specify a field or number fields to constrain which data
mongooplog will migrate. All other fields will be excluded
from the migration. Comma separate a list of fields to limit the applied
fields.
- --fieldFile <file>
- As an alternative to "--fields" the
--fieldFile option allows you to specify a file (e.g.
<file>) that holds a list of field names to include in
the migration. All other fields will be excluded from the
migration. Place one field per line.
- --seconds <number>, -s <number>
- Specify a number of seconds of operations for
mongooplog to pull from the remote host. Unless specified
the default value is 86400 seconds, or 24 hours.
- --from <host[:port]>
- Specify the host for mongooplog to retrieve
oplog operations from. mongooplog requires this
option.
Unless you specify the --host option, mongooplog will apply
the operations collected with this option to the oplog of the
mongod instance running on the localhost interface connected to
port 27017.
- --oplogns <namespace>
- Specify a namespace in the --from host where the
oplog resides. The default value is local.oplog.rs, which is the
where replica set members store their operation log. However, if
you've copied oplog entries into another database or collection,
use this option to copy oplog entries stored in another location.
Namespaces take the form of [database].[collection].
Usage¶
Consider the following prototype
mongooplog command:
mongooplog --from mongodb0.example.net --host mongodb1.example.net
Here, entries from the
oplog of the
mongod running on port
27017. This only pull entries from the last 24 hours.
In the next command, the parameters limit this operation to only apply
operations to the database
people in the collection
usage on the
target host (i.e.
mongodb1.example.net):
mongooplog --from mongodb0.example.net --host mongodb1.example.net --database people --collection usage
This operation only applies oplog entries from the last 24 hours. Use the
--seconds argument to capture a greater or smaller amount of time.
Consider the following example:
mongooplog --from mongodb0.example.net --seconds 172800
In this operation,
mongooplog captures 2 full days of operations. To
migrate 12 hours of
oplog entries, use the following form:
mongooplog --from mongodb0.example.net --seconds 43200
For the previous two examples,
mongooplog migrates entries to the
mongod process running on the localhost interface connected to the
27017 port.
mongooplog can also operate directly on MongoDB's
data files if no
mongod is running on the
target host. Consider
the following example:
mongooplog --from mongodb0.example.net --dbpath /srv/mongodb --journal
Here,
mongooplog imports
oplog operations from the
mongod
host connected to port
27017. This migrates operations to the MongoDB
data files stored in the
/srv/mongodb directory. Additionally
mongooplog will use the durability
journal to ensure that the
data files remain in a consistent state.
AUTHOR¶
MongoDB Documentation Project
COPYRIGHT¶
2011-2013, 10gen, Inc.
