Mongo DB Index name

Question

I created mongo db collection index using java code

dbCollection.createIndex("accountNumber");

When i see indices using

db.accounts.getIndexes()

I am getting the index name as "accountNumber_1"

How to get the index name also same as document field? or how to give index name?

Is naming indices important or i can ignore this?

Is there any specific reason you need to use the index name? When you hint to mongo which index to use in a query, you specify the field name that is indexed - not the actual index name: db.users.find().hint( { age: 1 } ) — Lix
– Lix, Commented Jan 19, 2016 at 8:46

zangw · Accepted Answer · 2016-01-19 08:57:27Z

When we create index on the document users

> db.users.createIndex({name: 1})
{
        "ok" : 0,
        "errmsg" : "Index with name: name_1 already exists with different option
s",
        "code" : 85
}

the name: name_1 is returned, then we can get the index through getIndexes()

> db.users.getIndexes()
[
        {
                "v" : 1,
                "key" : {
                        "_id" : 1
                },
                "name" : "_id_",
                "ns" : "test.users"
        },
        {
                "v" : 1,
                "unique" : true,
                "key" : {
                        "name" : 1
                },
                "name" : "name_1",
                "ns" : "test.users",
                "background" : true,
                "safe" : null
        }
]

We know, the name_1 is just the value of index name. and the key name is used to create index for document users. I think the name_1 is the value of name to meet BSON structure. We can ignore it...

Poorna Subhash · Accepted Answer · 2016-01-19 09:14:50Z

You can create index with the name you wanted using the other variant of createIndex method, refer java API here.


public void createIndex(DBObject keys,
                        DBObject options)
Creates an index on the field specified, if that index does not already exist.
Prior to MongoDB 3.0 the dropDups option could be used with unique indexes allowing documents with duplicate values to be dropped when building the index. Later versions of MongoDB will silently ignore this setting.

Parameters:
keys - a document that contains pairs with the name of the field or fields to index and order of the index
options - a document that controls the creation of the index.
MongoDB documentation
Index Creation Tutorials

You can corresponding mongodb documentation here.

Basically the second parameter 'options' contain an option to supply index name explicitly.

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