Docs Home → Develop Applications → MongoDB Manual
$indexStats (aggregation)
On this page
Definition
$indexStats
New in version 3.2.
Returns statistics regarding the use of each index for the collection. If running with access control, the user must have privileges that include
indexStats
action.The
$indexStats
stage takes an empty document and has the following syntax:{ $indexStats: { } } For each index, the return document includes the following fields:
Output FieldDescriptionname
Index name.Index key specification.
See also: spec.
The hostname and port of the
mongod
process.Statistics on the index use:
ops
is the number of operations that used the index.since
is the time from which MongoDB gathered the statistics.
The name of the shard associated with the host
Only available for a sharded cluster.
New in version 4.2.4.
The full specfication document for the index, which includes the index key specification document.
The index option
hidden
, available starting in MongoDB 4.4, is only included if the value istrue
.New in version 4.2.4.
Indicates if the index is currently being built.
Only available if
true
.New in version 4.2.4.
Statistics for an index will be reset on
mongod
restart or index drop and recreation.
Behavior
Accesses Field
The statistics reported by the accesses field only includes index access driven by user requests. It does not include internal operations like deletion via TTL Indexes or chunk split and migration operations.
Restrictions
$indexStats
must be the first stage in an aggregation pipeline.$indexStats
is not allowed in transactions.
Index Modifications Resets Statistics
Modification of an existing index (see collMod
command) resets the statistics for that index.
Example
For example, a collection orders
contains the following documents:
{ "_id" : 1, "item" : "abc", "price" : 12, "quantity" : 2, "type": "apparel" } { "_id" : 2, "item" : "jkl", "price" : 20, "quantity" : 1, "type": "electronics" } { "_id" : 3, "item" : "abc", "price" : 10, "quantity" : 5, "type": "apparel" }
Create the following two indexes on the collection:
db.orders.createIndex( { item: 1, quantity: 1 } ) db.orders.createIndex( { type: 1, item: 1 } )
Run some queries against the collection:
db.orders.find( { type: "apparel"} ) db.orders.find( { item: "abc" } ).sort( { quantity: 1 } )
To view statistics on the index use on the orders
collection,
run the following aggregation operation:
db.orders.aggregate( [ { $indexStats: { } } ] )
The operation returns a document that contains usage statistics for each index:
{ "name" : "item_1_quantity_1", "key" : { "item" : 1, "quantity" : 1 }, "host" : "examplehost.local:27018", "accesses" : { "ops" : NumberLong(1), "since" : ISODate("2020-02-10T21:11:23.059Z") }, "shard" : "shardA", // Available starting in MongoDB 4.2.4 if run on sharded cluster "spec" : { // Available starting in MongoDB 4.2.4 "v" : 2, "key" : { "item" : 1, "quantity" : 1 }, "name" : "item_1_quantity_1" } } { "name" : "item_1_price_1", "key" : { "item" : 1, "price" : 1 }, "host" : "examplehost.local:27018", "accesses" : { "ops" : NumberLong(1), "since" : ISODate("2020-02-10T21:11:23.233Z") }, "shard" : "shardA", // Available starting in MongoDB 4.2.4 if run on sharded cluster "spec" : { // Available starting in MongoDB 4.2.4 "v" : 2, "key" : { "item" : 1, "price" : 1 }, "name" : "item_1_price_1" } } { "name" : "item_1", "key" : { "item" : 1 }, "host" : "examplehost.local:27018", "accesses" : { "ops" : NumberLong(0), "since" : ISODate("2020-02-10T21:11:22.947Z") }, "shard" : "shardA", // Available starting in MongoDB 4.2.4 if run on sharded cluster "spec" : { // Available starting in MongoDB 4.2.4 "v" : 2, "key" : { "item" : 1 }, "name" : "item_1" } } { "name" : "_id_", "key" : { "_id" : 1 }, "host" : "examplehost.local:27018", "accesses" : { "ops" : NumberLong(0), "since" : ISODate("2020-02-10T21:11:18.298Z") }, "shard" : "shardA", // Available starting in MongoDB 4.2.4 if run on sharded cluster "spec" : { // Available starting in MongoDB 4.2.4 "v" : 2, "key" : { "_id" : 1 }, "name" : "_id_" } }