Best way to create index for MongoDB - mongodb

Question

I am having records stored in mongo-db collection for customer and there transactions with below format:
{
"_id" : ObjectId("59b6992a0b54c9c4a5434088"),
"Results" : {
"id" : "2139623696",
"member_joined_date" : ISODate("2010-07-07T00:00:00.000+0000"),
"account_activation_date" : ISODate("2010-07-07T00:00:00.000+0000"),
"family_name" : "XYZ",
"given_name" : "KOKI HOI",
"gender" : "Female",
"dob" : ISODate("1967-07-20T00:00:00.000+0000"),
"preflanguage" : "en-GB",
"title" : "MR",
"contact_no" : "60193551626",
"email" : "abc123#xmail.com",
"street1" : "address line 1",
"street2" : "address line 2",
"street3" : "address line 3",
"zipcd" : "123456",
"city" : "xyz",
"countrycd" : "Malaysia",
"Transaction" : [
{
"txncd" : "411",
"txndate" : ISODate("2017-08-02 00:00:00.000000"),
"prcs_date" : ISODate("2017-08-02 00:00:00.000000"),
"txn_descp" : "Some MALL : SHOP & FLY FREE",
"merchant_id" : "6587867dsfd",
"orig_pts" : "0.00000",
"text" : "Some text"
}
]
}
I want to create index on fields "txn_descp", "txndate", "member_joined_date", "gender", "dob" for faster access. Can some one help me in creating index for this document? Will appreciate any kind of help and suggestions.

Answer 1

While creating the index there are a few things to keep in mind.
Always create the index for the queries you use.
Go for compound indexes whenever possible.
First field in the index should be the one with the minimum possible values.Ie, if there is an index with gender and DOB as keys, It is better to have {gender:1,dob:1}