mongoDB : Discovering Indexes

db.system.indexes.find()

Above statement gives you all the indexes present in given database.

> use school
switched to db school
>
> db.system.indexes.find()
{ "v" : 1, "key" : { "_id" : 1 }, "name" : "_id_", "ns" : "school.students" }
{ "v" : 1, "key" : { "student_id" : 1 }, "name" : "student_id_1", "ns" : "school.students" }
{ "v" : 1, "key" : { "_id" : 1 }, "name" : "_id_", "ns" : "school.marks" }

db.students.getIndexes()

Above statement gives you all the indexes of students collection.

> db.students.getIndexes()
[
        {
                "v" : 1,
                "key" : {
                        "_id" : 1
                },
                "name" : "_id_",
                "ns" : "school.students"
        },
        {
                "v" : 1,
                "key" : {
                        "student_id" : 1
                },
                "name" : "student_id_1",
                "ns" : "school.students"
        }
]

db.students.dropIndex({"student_id" : 1})

Above statement drop the index created on field “student_id”.

> db.students.getIndexes()
[
        {
                "v" : 1,
                "key" : {
                        "_id" : 1
                },
                "name" : "_id_",
                "ns" : "school.students"
        },
        {
                "v" : 1,
                "key" : {
                        "student_id" : 1
                },
                "name" : "student_id_1",
                "ns" : "school.students"
        }
]
>
> db.students.dropIndex({"student_id" : 1})
{ "nIndexesWas" : 2, "ok" : 1 }
>
> db.students.getIndexes()
[
        {
                "v" : 1,
                "key" : {
                        "_id" : 1
                },
                "name" : "_id_",
                "ns" : "school.students"
        }
]
>

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