How to use the CreateIndex method?

[Jeffrey]

I am using mongodb-csharp driver version 1.2. There are three methods
to create an index in the class MongoCollection:
CreateIndex(array<String>)
CreateIndex(IMongoIndexKeys)
CreateIndex(IMongoIndexKeys, IMongoIndexOptions)
But I don't know how to use them. Can anyone give me some examples to
illustrate? And when I want to make the index unique or drop
duplicates, what should I do? Thank you!

[Robert Stam]

Use the first method when you want to create a simple index with all ascending keys:

    collection.CreateIndex("a", "b", "c");

Use the second method when you want to specify that some of the keys are descending:

    var keys = IndexKeys.Ascending("a", "b").Descending("c");

    collection.CreateIndex(keys);

Use the third method when you want to set any options for the index (like unique or dropDups):

    var keys = IndexKeys.Ascending("a", "b").Descending("c");

    var options = IndexOptions.SetUnique(true).SetDropDups(true);

    collection.CreateIndex(keys, options);

[Jeffrey]

If I create an index, is there any way to specify my own index name in
C# driver?

[Robert Stam]

Checkout all the available IndexOptions. You can name your index like this:

    var keys = IndexKeys.Ascending("a", "b", "c");

    var options = IndexOptions.SetName("abcIndex");

    collection.CreateIndex(keys, options);

2012/1/4 Jeffrey <hujun...@gmail.com>

[Manuel Sopena Ballesteros]

Hi Robert,

regarding the third method "collection.CreateIndex(keys, options)" how would you do using powershell?

thank you very much

[Robert Stam]

This worked for me:

Windows PowerShell

Copyright (C) 2009 Microsoft Corporation. All rights reserved.

PS C:\> Add-Type -Path "C:\mongodb\drivers\csharp\CSharpDriver-1.9.0\MongoDB.Bson.dll"

PS C:\> Add-Type -Path "C:\mongodb\drivers\csharp\CSharpDriver-1.9.0\MongoDB.Driver.dll"

PS C:\> $client = New-Object -TypeName "MongoDB.Driver.MongoClient" "mongodb://localhost"

PS C:\> $server = $client.GetServer()

PS C:\> $database = $server.GetDatabase("test")

PS C:\> $collection = $database.GetCollection("test")

PS C:\> $keys = [MongoDB.Driver.Builders.IndexKeys]::Ascending("a", "b", "c")

PS C:\> $options = [MongoDB.Driver.Builders.IndexOptions]::SetName("abcIndex")

PS C:\> $collection.CreateIndex($keys, $options)

DocumentsAffected   : 0

HasLastErrorMessage : False

LastErrorMessage    :

Upserted            :

UpdatedExisting     : False

Code                :

Command             :

CommandName         :

Response            : {ok=1, n=0}

ErrorMessage        :

Ok                  : True

ServerInstance      :

PS C:\>

You'll have to adjust the paths used in the Add-Type statements depending on where your driver DLLs are located.

Using the MongoDB shell, I ran this before those Powershell statements:

> db.test.drop()

true

> db.test.getIndexes()

[ ]

>

And using the MongoDB shell again afterwards, checked that the index was properly created:

> db.test.getIndexes()

[

        {

                "v" : 1,

                "key" : {

                        "_id" : 1

                },

                "name" : "_id_",

                "ns" : "test.test"

        },

        {

                "v" : 1,

                "key" : {

                        "a" : 1,

                        "b" : 1,

                        "c" : 1

                },

                "name" : "abcIndex",

                "ns" : "test.test"

        }

]

>

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