# How to add indices to a collection?

1. Add the index definition to a collection post the property definition. For example:

   collection Lottery{
   	property lotteryName : String
   	...
     property open:Boolean
   	
     index openIndx { // adds an index on open flag
   		up open
   	}
   	
     unique index lotteryNameIndx { //adds an unique index
   		up lotteryName
   	}
     
     index nameOpenIndx { //compound index
   		up lotteryName
   		up open
   	}
   	
   }
   

   Note: Dont forget to save the file

2. enter sbt shell, run compile command.

3. run command ensureIndices to apply the indices to the collection on mongo server.

   [Lottery] $ LotteryMongo/collection ensureIndices Lottery
   

Advance options:

• sparse indices can also be created.
• index a field with down i.e. reverse ordering
• index string fields with text option available.

Note: while using compound indices ensure the query conditions honour the index ordering. More details here