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- getLastError
getLastError¶
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Definition¶
-
getLastError
¶ Returns the error status of the preceding operation on the current connection. Clients typically use
.getLastError
in combination with write operations to ensure that the write succeeds.getLastError
uses the following prototype form:getLastError
uses the following fields:Field Type Description j
Boolean If true
, wait for the next journal commit before returning, rather than waiting for a full disk flush. Ifmongod
does not have journaling enabled, this option has no effect. If this option is enabled for a write operation,mongod
will wait no more than 1/3 of the currentjournalCommitInterval
before writing data to the journal.w
integer or string When running with replication, this is the number of servers to replicate to before returning. A w
value of 1 indicates the primary only. Aw
value of 2 includes the primary and at least one secondary, etc. In place of a number, you may also setw
tomajority
to indicate that the command should wait until the latest write propagates to a majority of replica set members. If usingw
, you should also usewtimeout
. Specifying a value forw
without also providing awtimeout
may causegetLastError
to block indefinitely.fsync
Boolean If true
, wait formongod
to write this data to disk before returning. Defaults to false. In most cases, use thej
option to ensure durability and consistency of the data set.wtimeout
integer Optional. Milliseconds. Specify a value in milliseconds to control how long to wait for write propagation to complete. If replication does not complete in the given timeframe, the getLastError
command will return with an error status.See also
Write Concern, Write Concern Reference, and Replica Acknowledged.
Output¶
Each getLastError()
command returns a document containing a
subset of the fields listed below.
-
getLastError.
ok
¶ ok
istrue
when thegetLastError
command completes successfully.Note
A value of
true
does not indicate that the preceding operation did not produce an error.
-
getLastError.
err
¶ err
isnull
unless an error occurs. When there was an error with the preceding operation,err
contains a textual description of the error.
-
getLastError.
connectionId
¶ The identifier of the connection.
-
getLastError.
lastOp
¶ When issued against a replica set member and the preceding operation was a write or update,
lastOp
is the optime timestamp in the oplog of the change.
-
getLastError.
n
¶ n
reports the number of documents updated or removed, if the preceding operation was an update or remove operation.
-
getLastError.
shards
¶ When issued against a sharded cluster after a write operation,
shards
identifies the shards targeted in the write operation.shards
is present in the output only if the write operation targets multiple shards.
-
getLastError.
singleShard
¶ When issued against a sharded cluster after a write operation, identifies the shard targeted in the write operation.
singleShard
is only present if the write operation targets exactly one shard.
-
getLastError.
updatedExisting
¶ updatedExisting
istrue
when an update affects at least one document and does not result in an upsert.
-
getLastError.
upserted
¶ upserted
is an ObjectId that corresponds to the upserted document if the update resulted in an insert.upserted
is only present in the output ofgetLastError
if the update statement did not include an_id
field.
-
getLastError.
wnote
¶ If set,
wnote
indicates that the preceding operation’s error relates to using thew
parameter togetLastError
.See
Write Concern Reference for more information about
w
values.
-
getLastError.
wtimeout
¶ wtimeout
istrue
if thegetLastError
timed out because of thewtimeout
setting togetLastError
.
-
getLastError.
waited
¶ If the preceding operation specified a timeout using the
wtimeout
setting togetLastError
, thenwaited
reports the number of millisecondsgetLastError
waited before timing out.
-
getLastError.
writtenTo
¶ Array that lists the replica set members that have acknowledged the write operation.
-
getLastError.
wtime
¶ wtime
is the number of milliseconds spent waiting for the preceding operation to complete. IfgetLastError
timed out,wtime
andgetLastError.waited
are equal.
Examples¶
Confirm Replication to Two Replica Set Members¶
The following example ensures the operation has replicated to two members (the primary and one other member):
Confirm Replication to a Majority of a Replica Set¶
The following example ensures the write operation has replicated to a majority of the configured members of the set.
Set a Timeout for a getLastError
Response¶
Unless you specify a timeout, a getLastError
command may
block forever if MongoDB cannot satisfy the requested write
concern. To specify a timeout of 5000 milliseconds, use an invocation
that resembles the following:
When wtimeout
is 0
, the getLastError
operation
will never time out.