No default compound index created on time series collection

Working with Data Java Frameworks
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1

I am using MongoDb version 7.0.2 and I am creating a new time series collections using Java MongoDb API with Spring.

This is the code that creates the collections:

TimeSeriesOptions tso = new TimeSeriesOptions("my_time_field")
                .granularity(TimeSeriesGranularity.HOURS)
                .metaField("my_meta_field");

CreateCollectionOptions cco = new CreateCollectionOptions().timeSeriesOptions(tso).expireAfter(30, DAYS);

mongoTemplate.getMongoDatabaseFactory().getMongoDatabase().createCollection("time_series_collection_name",  cco);

The collections are created successfully but here in the documentation it is stated that
MongoDB 6.3 and later automatically creates a compound index on the time and metadata fields for new time series collections.
It can be found on this page: https://mongodb.prakticum-team.ru/docs/v7.0/core/timeseries-collections/
The problem is that my time series collections don’t have any index associated with them when they are created.
Is this a bug or I am missing something?

3

Update: I am answering my own question.
I have executed the following create collection command using mongosh on two different MongoDB editions and the result is different:

db.createCollection("my_test_collection", {timeseries:{timeField:"timestamp",metaField:"metadata"}});

MongoDb Community edition v 7.0.2 - The time series collection is created but there is no default index created associated with this collection
MongoDb Atlas edition v 7.0.2 - The time series collection is created and a default index associated with this collection is created

[
  {
    v: 2,
    key: { metadata: 1, timestamp: 1 },
    name: 'metadata_1_timestamp_1'
  }
]

This is the default index that is created.

As a conclusion I can say that there is difference in the behaviour of different MongoDb editions but maybe it is good to state that in the documentation that I linked in my question.

4

Hey @Vladimir_Stoyanov,

Welcome to the MongoDB Community!

I tested it with MongoDB Community version 7.0.2, and it worked as expected for me. I’ve attached a screenshot for your reference, showing that it automatically created the compound index for the TS collection in the local deployment too.

mongosh
mongosh2286×1152 310 KB

Could you please share the workflow you are following to create a TS collection?

Best regards,
Kushagra

5

Hi @Kushagra_Kesav,
Thank you for your response.

Here are exactly the steps I follow.

MongoDbTimeSeriesProblem
MongoDbTimeSeriesProblem1746×868 91.4 KB

I have installed my MongoDb using brew command on Mac OS

Thanks,
Vladimir