Feature Support

This section provides details on supported client and server features of the Oracle API for MongoDB.

Client Tools and Drivers

The Oracle API for MongoDB requires a MongoDB client that supports load balanced connections. The following list provides minimal versions for some client drivers and tools:

• C 1.19.0
• C# 2.13.0
• Compass 1.28.1
• Database Tools 100.5.0 (includes mongoexport, mongorestore, and mongodump)
• Go 1.6.0
• Java 4.3.0
• MongoSH 0.15.6
• Node.js driver 4.1.0
• PyMongo 3.12.0 (for Python language)
• Ruby 2.16.0
• Rust 2.1.0

You can download these drivers from https://www.mongodb.com/docs/drivers/.

Preview Features

Some Oracle API for MongoDB functionality is available as preview features.

Preview features are provided so that you can evaluate new functionality before it becomes generally available. Preview features are fully supported from a security perspective and are suitable for evaluation and testing. However, because the feature is still under development, Oracle reserves the right to modify or remove the functionality, behavior, syntax, or semantics in a future release without preserving backward compatibility.

Preview features are disabled by default.

You can enable preview features in one of the following ways:

• Database-wide by setting the mongo.preview property.
• For individual MongoDB statements by explicitly requesting preview functionality.

Enabling Preview Features Database-Wide

Enable preview features for your database for all Oracle API for MongoDB sessions by setting the mongo.preview property. This is a non-schema scoped property.

BEGIN
  ords_admin.set_property(
    p_key   => 'mongo.preview',
    p_value => 'true');
END;
/
commit;

The property value is case sensitive, so you have to specify ‘true’ in lowercase. You also need to commit this change explicitly.

After this property is enabled, all newly established Oracle API for MongoDB connections use preview functionality.

To check the proper setting of this property, you can query the ORDS properties as follows:

SELECT key, value FROM user_ords_properties WHERE key = 'mongo.preview';

Note:

• ORDS caches configuration properties. After changing the mongo.preview property, it can take several minutes before the new setting becomes effective. (Engineering note: replace with the documented cache refresh interval.)
• Existing MongoDB client connections continue using the previous configuration. Disconnect and reconnect your MongoDB client after enabling or disabling preview mode.

Enabling Preview Features for Individual Statements

You can also enable preview features for individual MongoDB statements. Depending on the API, preview functionality can be requested by an individual command or within an aggregation pipeline. This allows you to evaluate preview functionality without enabling it for the entire database.

The following example creates a vector search index by enabling preview for the createSearchIndex command:

db.movies.createSearchIndex(
  "vector_idx",
  {
    fields: [
      {
        type: "vector",
        path: "embedding",
        numDimensions: 768,
        similarity: "cosine"
      }
    ]
  },
  {
    preview: true
  }
)

The following example enables preview for the $vectorSearch aggregation pipeline stage by specifying the $preview hint:

db.MOVIES.aggregate([
  {
    $vectorSearch: {
      index: "summary_vec_idx",
      path: "summary_embedding",
      queryVector: /* vector here */,
      limit: 5,
      exact: false,
      hint: { "$preview": 1 }
    }
  }
]);

Only the command or aggregation pipeline operator that explicitly requests preview functionality executes in preview mode. Other commands and operators continue to use the default behavior unless preview is explicitly requested.

Preview features are explicitly marked in the subsequent sections.

Database Commands

This section lists MongoDB commands that are supported by the Oracle API for MongoDB.

Aggregation Commands

Authentication Commands

Diagnostic

Query and Write Operation

Role Management Commands

Replication Commands

Sessions Commands

User Management Commands

Sharding Commands

Operators

Array Query Operators

Bitwise Query Operators

Comparison Query Operators

Element Query Operators

Evaluation Query Operators

Geospatial Query Operators

Logical Query Operators

Projection Operators

Array Update Operators

Bitwise Update Operator

Field Update Operators

Modifier Update Operators

Aggregation Pipeline Stages

$lookup Aggregation Pipeline Stage

Restrictions on the use of stage $lookup are described.

• Field let is not supported. An error is raised if you use it.
• If the value of field localField is a field that’s missing from any input documents then an error is raised. (The missing field is not treated as if it were present with the value of null.)
• If the value of field localField is an array, or if it is a field that occurs more than once in an input document (thus producing multiple values), then an error is raised.
• If the value of field foreignField is a field that’s missing from the input documents then no documents match (no error is raised). This includes the case where the document field specified by field localField is missing or has a null value.

Aggregation Pipeline Operators and Expressions

Arithmetic Operators

Trigonometry Operators

Array Operators

Boolean Operators

Comparison Operators

Conditional Operators

Date Operators

Literal Operator

Object Operators

Set Operators

String Operators

Text Operators

Type Operators

Accumulator Operators

Variable Operators

System Variables

Miscellaneous Operators

Data Types

Support of MongoDB BSON data types:

Unsupported types are converted to strings on load.

Indexes

Index options