CODEWITHSUNDEEP
c#.netmongodbindexing
OldShaterhan
OldShaterhan

Reputation: 175

How to remove index without knowing its name?

I want to remove index using MongoDB .NET Driver (v.2.11). The issue is that I don't want to use index name, instead I would like to remove it like in: https://docs.mongodb.com/manual/tutorial/manage-indexes/ Remove Specific Index section - providing index schema. How can it be done? Now using of:

MyCollection.Indexes.DropOne("{ _id: 1, somefield: 1 }");

results in:

MongoDB.Driver.MongoCommandException: 'Command dropIndexes failed: index not found with name [{ _id: 1, somefield: 1 }].'

Note: Index exists in collection.

Upvotes: 0

Views: 1289

Answers (2)

Kevin Smith
Kevin Smith

Reputation: 14436

There is no way currently in the C# Driver to drop an index based on its keys.

You could however search for the index and get the name and then drop the index like the following.

var client = new MongoClient();
var database = client.GetDatabase("test");
var collection = database.GetCollection<Person>("people");

// Create a index
var keys = Builders<Person>.IndexKeys.Ascending(x => x.Surname);
await collection.Indexes.CreateOneAsync(new CreateIndexModel<Person>(keys));

var cursor = await collection.Indexes.ListAsync();

// Find the index 
var indexKeys = BsonDocument.Parse("{ Surname: 1 }");
var indexName = (await cursor.ToListAsync())
    .Where(x => x["key"] == indexKeys)
    .Select(x => x["name"])
    .Single();

// Drop index by name
await collection.Indexes.DropOneAsync(indexName.AsString);

Upvotes: 1

D. SM
D. SM

Reputation: 14520

The dropIndex command supports giving the index specification. You can invoke it using your driver's helper for executing arbitrary commands, if your driver does not provide a dropIndex helper that takes an index specification.

MyCollection.Indexes.DropOne("{ _id: 1, somefield: 1 }");

You tried to drop an index with the name of "{ _id: 1, somefield: 1 }". At a minimum you should be using the correct syntax for maps in your programming language.

Upvotes: 0

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