Shulou(Shulou.com)06/01 Report--

First, we need to introduce the role of the mongodb local library.

The local library is the system library of MongoDB, which records information such as timestamps and indexes and replication sets.

Test:PRIMARY > use local

Switched to db local

Test:PRIMARY > show tables

System.replset

Me

Startup_log

Replset.minvalid

Oplog.rs

Replset.election

Test:PRIMARY >

What is recorded separately by each collection under the local library

The me collection under the local library holds the server name

The replset.minvalid collection under the local library holds the timestamp of the latest operation in the database.

The startup_log collection under the local library records the startup information of each mongod.

The system.indexes collection under the local library records all index information for the current library

The system.replset under the local library records the member configuration information of the replication set rs.conf () reads this collection

The oplog.rs collection under the local library records all operations, and MongoDB synchronizes data through oplog.rs. When the Primary node inserts a piece of data, there will be one more record in the oplog.rs collection

Op: operation type, insert corresponding I; update corresponding u; delete corresponding d; but in one case, n, which means no operation (no-op), tightly represents a message message.

For example:

Query the insert record in oplog, corresponding to the record whose op is I:

Test:PRIMARY > db.oplog.rs.find ({"op": "I"}). Pretty (). Limit (3)

Check the update operation command:

Test:PRIMARY > db.oplog.rs.find ({"op": "u"}). Pretty (). Limit (3)

Test:PRIMARY >

Check the delete operation command:

Test:PRIMARY > db.oplog.rs.find ({"op": "d"}). Pretty (). Limit (3)

Check the operation according to the time range:

For example:

Find the operation record after September 1, 2017:

Test:PRIMARY > db.oplog.rs.find ({"o.createTime": {$gte:new Date)}) .limit (3)

Check the operation records between September 1 and October 31, 2017:

Test:PRIMARY > db.oplog.rs.find ({"o.createTime": {$gte:new Date), $lte:new Date}) .limit (3)

Let's check all the oplog records that operate on the chenfeng table

Test:PRIMARY > db.oplog.rs.find ({ns: "testdb.chenfeng"})

Check the timestamp of the operation:

Db.oplog.rs.find ({"op": "I", "ns": "testdb.chenfeng",}, {ts:1}) .pretty ()

{"ts": Timestamp (1509246747, 1)}

{"ts": Timestamp (1509246747, 2)}

{"ts": Timestamp (1509246747, 3)}

{"ts": Timestamp (1509246747, 4)}

{"ts": Timestamp (1509246747, 5)}

Timestamp of the current operation time point:

Test:PRIMARY > rs.status (). Members [0] .optime.ts

Timestamp (1509247609, 3001)

How to back up oplog collections:

[root@192 new] # mongodump-- host localhost-- port 9336-uadmin-padmin-- authenticationDatabase=admin-d local-c oplog.rs-o / root/new

2017-10-29T12:36:45.605+0800 writing local.oplog.rs to local/oplog.rs.bson

2017-10-29T12:36:48.606+0800 [#...] Local.oplog.rs 398917Compact 4937240 (8.1%)

2017-10-29T12:36:51.610+0800 [# #.] Local.oplog.rs 812569 Compact 4937240 (16.5%)

2017-10-29T12:36:54.611+0800 [#.] Local.oplog.rs 1208741 Compact 4937240 (24.5%)

2017-10-29T12:36:57.607+0800 [#.] Local.oplog.rs 1570342 Compact 4937240 (31.8%)

2017-10-29T12:37:00.617+0800 [#.] Local.oplog.rs 1948323 Compact 4937240 (39.5%)

2017-10-29T12:37:03.606+0800 [#.] Local.oplog.rs 2346269 Compact 4937240 (47.5%)

2017-10-29T12:37:06.606+0800 [#.] Local.oplog.rs 2741569 Compact 4937240 (55.5%)

2017-10-29T12:37:09.609+0800 [#.] Local.oplog.rs 3137392 Compact 4937240 (63.5%)

2017-10-29T12:37:12.606+0800 [#.] Local.oplog.rs 3533685 Compact 4937240 (71.6%)

2017-10-29T12:37:15.610+0800 [#.] Local.oplog.rs 3897290Compact 4937240 (78.9%)

2017-10-29T12:37:19.672+0800 [#.] Local.oplog.rs 3947430 Compact 4937240 (80.0%)

2017-10-29T12:37:21.609+0800 [#....] Local.oplog.rs 4147978 amp 4937240 (84.0%)

2017-10-29T12:37:24.607+0800 [#...] Local.oplog.rs 4518546 Compact 4937240 (91.5%)

2017-10-29T12:37:27.606+0800 [# #.] Local.oplog.rs 4910376 Compact 4937240 (99.5%)

2017-10-29T12:37:27.758+0800 writing local.oplog.rs metadata to local/oplog.rs.metadata.json

2017-10-29T12:37:27.770+0800 done dumping local.oplog.rs (4937240 documents)

Use bsondump to check the operation record:

Check the insert operation:

# bsondump oplog.rs.bson | grep "\" op\ ":\" I\ "" | head

Check and delete operation:

# bsondump oplog.rs.bson | grep "\" op\ ":\" d\ "" | head

Check update operation:

[root@192 local] # bsondump oplog.rs.bson | grep "\" op\ ":\" u\ "" | head

Restore the oplog collection command:

Mongorestore-host localhost-port 9336-uadmin-padmin-authenticationDatabase=admin-d local-c oplog.rs / root/new/local/oplog.rs.bson

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