CODEWITHSUNDEEP
mongodb
Zach
Zach

Reputation: 19082

How do you get the size of an individual index in MongoDB?

I know I can use db.collection.totalIndexSize() to get the total index size, but I'm interested in seeing the size of an individual index.

Is this supported?

Upvotes: 44

Views: 30684

Answers (4)

Shubham Taneja
Shubham Taneja

Reputation: 1

Hey Just add a value in the totalIndexSize() function as

  • db.collection.totalIndexSize(1)

for example

db.test.totalIndexSize(1)

Upvotes: -1

Subhranath Chunder
Subhranath Chunder

Reputation: 533

Listing down the size of indexes per collection in a specific db we can use the following code snippet:

use mydb;

var collectionStats = []

// Get the sizes
db.getCollectionNames().forEach(function (collectionName) {
    var collection = db.getCollection(collectionName)
    var collectionIndexSize = collection.totalIndexSize();
    var indexSizeInMB = collectionIndexSize/(1024*1024)
    collectionStats.push({"collection": collectionName, "indexSizeInMB": indexSizeInMB})
});

// Sort on collection name or index size
var reverse = true;
var sortField = "indexSizeInMB";
collectionStats.sort(function (a, b) {
    comparison = a[sortField] - b[sortField];
    if (isNaN(comparison)) comparison = a.collection.localeCompare(b.collection);
    if (reverse) comparison *= -1;
    return comparison;
});undefined;

// Print the collection stats
collectionStats.forEach(function (collection) {
    print(JSON.stringify(collection));
});

// Total size of indexes
print("Total size of indexes: " + db.stats()["indexSize"]/(1024*1024) + " MB");

You can change the value of variables in the snippet above

var reverse = true;
var sortField = "indexSizeInMB";

to change the sorting field and order.

Upvotes: 9

Nico
Nico

Reputation: 4416

This is an easy script to find out the indexes that take up the most space in your entire database:

var indexesArr = {}
db.getCollectionNames().forEach(function(collection) {
   indexes = db[collection].stats().indexSizes
   for (i in indexes) indexesArr[collection + " - " + i] = indexes[i];
});

var sortable = [], x;
for (x in indexesArr) sortable.push([x, indexesArr[x]])
var pArr = sortable.sort(function(a, b) {return b[1] - a[1]})
for (x in pArr) print( pArr[x][1] + ": " + pArr[x][0] );

Upvotes: 9

Remon van Vliet
Remon van Vliet

Reputation: 18595

Certainly can. db.collection.stats().indexSizes is an embedded document where each index name is a key and the value is the total index size in bytes :

> db.test.stats()
{
        "ns" : "test.test",
         <snip>
        "indexSizes" : {
                "_id_" : 137904592,
                "a_1" : 106925728
        },
        "ok" : 1
}

Upvotes: 66

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