Some of the most important commands and references information for Mongo DBA

MongoDBA.txt

-------------Manually Install MongoDB Service -----------
mkdir c:\mongodata\inMemory\db
mkdir c:\mongodata\mmapv1\db
mkdir c:\mongodata\wiredTiger\db
mkdir c:\mongodata\inMemory\log
mkdir c:\mongodata\mmapv1\log
mkdir c:\mongodata\wiredTiger\log

sc.exe create MongoInMemory binPath= "\"C:\Program Files\MongoDB\Server\3.4\bin\mongod.exe\" --service --config=\"C:\Program Files\MongoDB\Server\3.4\inMemory.cfg\"" DisplayName= "MongoInMemory" start= "auto"
sc.exe create MongoWiredTiger binPath= "\"C:\Program Files\MongoDB\Server\3.4\bin\mongod.exe\" --service --config=\"C:\Program Files\MongoDB\Server\3.4\wiredTiger.cfg\"" DisplayName= "MongoWiredTiger" start= "auto"
sc.exe create MongoMmapv1 binPath= "\"C:\Program Files\MongoDB\Server\3.4\bin\mongod.exe\" --service --config=\"C:\Program Files\MongoDB\Server\3.4\mmapv1.cfg\"" DisplayName= "MongoMmapv1" start= "auto"

net start MongoInMemory
net start MongoWiredTiger
net start MongoMmapv1

sc delete MongoInMemory --- Delete the service 
sc queryex MongoInMemory  ---> serach Serices 

sc queryex type= service state= inactive  --> Search InActive Seriveces 

-------start mongo service ------
net start mongoInMemory  (mongoWiredTiger, mongoMmapv1)
net stop mongoInMemory

netsh interface ip show address    --> show ip address 
------------ get mongo server status from mongo shell-----
$db.serverStatus()

--------------- Mongo server web -----
http://localhost:28017/ -------> port 1000 above mongod server port 

-------------- Dump mongo db -----------
mongodump --host [..] --port [...] --out [...]
mongodump --oplog --port 30100   -----> dump live changes only in replication 
mongodump --db control_tower_dev      -----> single db 
mongodump --db  ... --collection  ...  --> comllection 

mongodump --host mongodb1.example.net --port 3017 --username user --password "pass" --out /opt/backup/mongodump-2013-10-24
------------- Restore 
mongorestore dirctory 
mongorestore --drop sourcedir  ---------> Overwrite 
mongorestore --drop --collection collection --db database sourcedir 
mongorestore --oplogReplay                      --> backup cerated with oplog that will be relay  

---------------- Import/Export 

mongoexport --db database --collection collname       ------stio stream 
mongoexport --db database --collection collname > filename    ---> stream into file 
mongoexport --db database --collection collname --fields f1,f2 
mongoexport --query "{_id:{$gt:2}}"

--------------- indexing 
db.collection.getIndexes()    -----> get the indexes
db.system.indexes.find()
db.collection.ensureIndex({field:1})      --> 1 -- assending 
db.collection.dropIndex('indexName')
db.collection.ensureIndex({'doc.subdoc': 1})


db.collection.find({}).explain()             ---explain query plan  
db.collection.find({}).explain('executionStats') 

sparse index ---- 
db.collection.stats() -----> statistic of the collection 
sparse uniquie index --- > Can allowed multiple null/missing values 
TTL Indexes --> Time to live 

--------------- Replica set 
mongod --dbpath c:\freshDb --replSet r1 --oplogSize 100 
mongo   --> connect to mongod service 
> rs.initiate()   ---> Initialize the replica set 
> rs.config()
> var conf = rs.conf()           --> store conf 
> rs.reconfig(conf)             --> reconfigure 
> rs.status()                  --> replica health 

----------Elections ----------
Only one instance can be primary at a time in replica set 
Elections is to choose the primary instance 
Arbiter --> Votes but dont have data 
Max of 7 voter in elections 

Start 3 mongod server on different port 
start mongod --dbpath \freshDb\m1 --port 30001 --replSet r1
start mongod --dbpath \freshDb\m2 --port 30002 --replSet r1 
start mongod --dbpath \freshDb\m3 --port 30003 --replSet r1

Connect to the serices and initiate replica sets 
mongo --port 30001
> rs.initiate()
> rs.add("DIPTE-E7450:30002")           --> machineName:port add other machine to replicaset 
> rs.config()
> rs.add("DIPTE-E7450:30003", true)     --> Add as arbiter 
> rs.config()
> rs.status()
> for(i=0; i< 1000; i++){db.demo.save({_id:i})}  --- Write some documents to primary and check replication
> db = connect("DIPTE-E7450:30002/demo")        --> connecting to 30002 server through shell 
> db.demo.find() ---> error  for safty reason 
> db.getMongo().setSlaveOk()
> db.getReplicationInfo()
> rs.printReplicationInfo()

--------Failover --------
Kill primary on 30001 while shell connecting to secondery 
> rs.status()
Secondery should becoms primary
Kill the arbiter 
Primary will change to secondery no one can vote > 50 % 
Start the server again 
start mongod --dpath \freshDb\m2 --port 30002 --replSet r1 

-------------Priority ----------
priority will do favor to elect as primary if its healthy 
> var conf = rs.conf()
> conf.members[0].priority = 10
> rs.reconfig(conf)
> rs.conf()    ---> alwase reconfig from primary or force the changes by rs.reconfig(conf,{force:true})
> db.getMongo()   --> which server connected to 

----------------- Step down ------
Changes in live system 
Stepdown the primary and take over by other 

>rs.stepDown(3*60)        -- stepDown for 3 min 
>db.adminCommand({replSetStepDown: 86400, force: 1}) Stepdown forrce for 24 Hrs 
> rs.status()

-------------- Freez -------------
freez secondery not to become primary for given time 
> rs.freez(5*60)        --> 5 min 

------------- Hidden ------------
Application cant see it so it cant be primary 
But can vote 
> var conf = rs.conf()
> conf.members[0].priority = 0     ---> never become primary 
> conf.members[0].hidden = true 
> rs.reconfig(conf)

------------ Chaining ------------ 
Decide which instance should replicate from which one 
Multiple secondery can replicate from secondery instead of single primary 

------------- Write conrcen ----------
mongo will aknowledge only once condition fullfil 
> db.demo.insert({x: 'Hi'}, {writeConcern: {w:2}})    --- w : write to disk, j: write to journel 
wait for write from 2 machine 
> db.demo.insert({x: 'Hi'}, {writeConcern: {w:'majority', j: true}})


---------------- Sharding --------------
Horizontal spliting of the collection 
Part of the collection can reside on the shard collection 
Shard --> server holding part of the collection 
Config --> stored config about which part collection reside where 
mongos --> shard server, router for application commands, decide routing internally 

start mongod --configsvr --dbpath \freshDb\config1 replSet r1       ---> start configServer 
start mongos --configdb r1/DIPTE-E7450                       --> start shard server by specifying config server replicaset/host 

start other servers 
start mongod --dbpath \freshDb\m1 --replSet r1 --port 30001
start mongod --dbpath \freshDb\m2 --replSet r1 --port 30002

Configure shards from sharding server mongos 
mongo 
add shard 
> sh.addShard("r1/DIPTE-E7450:30001")
> sh.addShard("r1/DIPTE-E7450:30002")
> sh.status()

------------------------- Monitoring --------------











---------------------- Indexes ------------------------ 
db.collection.getIndexes()  --> list all indexes
--- List all Indexes on a Database 
db.getCollectionNames().forEach(function(collection) {
   indexes = db[collection].getIndexes();
   print("Indexes for " + collection + ":");
   printjson(indexes);
});


db.Shipment.createIndex({tenantId: 1})  --create index 
db.Shipment.dropIndex({tenantId: 1})   -- Drop Index 
db.Shipment.dropIndexes()              -- Drop all the indexes 
 
db.Shipment.reIndex()				 -- Drop all indexes and rebuild it 



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