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- The
local
Database
The local
Database¶
On this page
Overview¶
Every mongod
instance has its own local
database, which
stores data used in the replication process, and other
instance-specific data. The local
database is invisible to
replication: collections in the local
database are not replicated.
When running with authentication (i.e. auth
), authenticating against the local
database is equivalent to authenticating against the admin
database. This authentication gives access to all databases.
In replication, the local
database store stores internal replication
data for each member of a replica set. The local
database contains the
following collections used for replication:
Collections on Replica Set Members¶
-
local.system.
replset
¶ local.system.replset
holds the replica set’s configuration object as its single document. To view the object’s configuration information, issuers.conf()
from themongo
shell. You can also query this collection directly.
-
local.oplog.
rs
¶ local.oplog.rs
is the capped collection that holds the oplog. You set its size at creation using theoplogSize
setting. To resize the oplog after replica set initiation, use the Change the Size of the Oplog procedure. For additional information, see the Oplog Internals topic in this document and the Oplog topic in the Replica Set Fundamental Concepts document.
-
local.replset.
minvalid
¶ This contains an object used internally by replica sets to track replication status.
-
local.
slaves
¶ This contains information about each member of the set and the latest point in time that this member has synced to. If this collection becomes out of date, you can refresh it by dropping the collection and allowing MongoDB to automatically refresh it during normal replication: