MongoDB : Basic Administration

After going through CRUD operations on MongoDB database, We will take look at some more basic MongoDB Administration

Getting MongoDB database-related information

If you want to know databases available in the system, execute "show dbs" command, it will list out all the databases

> show dbs;

admin      0.000GB

config     0.000GB

local      0.016GB

techno_db  0.001GB

> 

If you want to know in which database, you are currently execute db 

> db

techno_db

> 

if you are curious about what are the collections available under the database, just execute show collections or show tables

>show collections;

tech_large

techno_col

> 

or

> show tables;

tech_large

techno_col

> 

The command db.stats() will give you all the stats about the database 

> db.stats();

{

        "db" : "techno_db",

        "collections" : 2,

        "views" : 0,

        "objects" : 17000,

        "avgObjSize" : 37.64705882352941,

        "dataSize" : 640000,

        "storageSize" : 335872,

        "numExtents" : 0,

        "indexes" : 2,

        "indexSize" : 208896,

        "fsUsedSize" : 587198464,

        "fsTotalSize" : 10693378048,

        "ok" : 1,

        "operationTime" : Timestamp(1549877990, 1),

        "$clusterTime" : {

                "clusterTime" : Timestamp(1549877990, 1),

                "signature" : {

                        "hash" : BinData(0,"OFOjmV2iLyqywB6fMf4bdiUZ5CU="),

                        "keyId" : NumberLong("6636938165653340162")

                }

        }

}

> 

If you want to know stats about only particular collections then that is also possible, execute db..stats() command

  

> db.techno_col.stats();

{

        "ns" : "techno_db.techno_col",

        "size" : 70000,

        "count" : 2000,

        "avgObjSize" : 35,

        "storageSize" : 86016,

        "capped" : false,

        "wiredTiger" : {

                "metadata" : {

                        "formatVersion" : 1

                },

                "creationString" :

…

…

…

},

        "nindexes" : 1,

        "totalIndexSize" : 61440,

        "indexSizes" : {

                "_id_" : 61440

        },

        "ok" : 1,

        "operationTime" : Timestamp(1549878100, 1),

        "$clusterTime" : {

                "clusterTime" : Timestamp(1549878100, 1),

                "signature" : {

                        "hash" : BinData(0,"eBwJSS4K5vUHyZJKT54h2pduSEc="),

                        "keyId" : NumberLong("6636938165653340162")

                }

        }

}

> 

Getting Help

MongoDB provides by default build command called db.help(), it lists out commonly used methods for operating database

we can get the type command on any collections using db..help()

> db.help();

DB methods:

        db.adminCommand(nameOrDocument) - switches to 'admin' db, and runs command [just calls db.runCommand(...)]

        db.aggregate([pipeline], {options}) - performs a collectionless aggregation on this database; returns a cursor

        db.auth(username, password)

        db.cloneDatabase(fromhost) - deprecated

        db.commandHelp(name) returns the help for the command

        db.copyDatabase(fromdb, todb, fromhost) - deprecated

        db.createCollection(name, {size: ..., capped: ..., max: ...})

        db.createView(name, viewOn, [{$operator: {...}}, ...], {viewOptions})

        db.createUser(userDocument)

        db.currentOp() displays currently executing operations in the db

...

...

...

        db.shutdownServer()

        db.stats()

        db.version() current version of the server

> 

> db.techno_col.help();

DBCollection help

       db.techno_col.find().help() - show DBCursor help

       db.techno_col.bulkWrite( operations, )- ulk execute write operations, optional parameters are: w, wtimeout, j

        db.techno_col.count( query = {}, ) - count the number of documents that matches the query, optional parameters are: limit, skip, hint, maxTimeMS

...

...

...

        db.techno_col.unsetWriteConcern( ) - unsets the write concern for writes to the collection

        db.techno_col.latencyStats() - display operation latency histograms for this collection

>  

There is one method to increase the speed of your administration by simply using the tab key on the keyboard

Just type function or procedure name and press tab, it will all available functions under it

> db.techno_col.get

db.techno_col.getCollection(        db.techno_col.getIndexSpecs(    db.techno_col.getName(             db.techno_col.getShardVersion(

db.techno_col.getDB(                db.techno_col.getIndexes(        db.techno_col.getPlanCache(         db.techno_col.getSlaveOk(

db.techno_col.getFullName(          db.techno_col.getIndices(        db.techno_col.getQueryOptions(  db.techno_col.getSplitKeysForChunks(

db.techno_col.getIndexKeys(           db.techno_col.getMongo(        db.techno_col.getShardDistribution(   db.techno_col.getWriteConcern(

To get the definition of any method can be found using not providing brackets at the time of invocation of the method

for example

> db.techno_col.getIndexes

function (filter) {

    var res = this._getIndexesCommand(filter);

    if (res) {

        return res;

    }

    return this._getIndexesSystemIndexes(filter);

}

>