• Supported and Jepsen-tested
• Synchronous replication with immediate consistency meaning any client can read the latest writ
• Open source

Reference

MongoDB does not support ACID transactions. Instead, MongoDB exchanges ACID transactions for eventual consistency. This is a much weaker safety guarantee than an ACID-compliant database.

Distributed transactions are supported. However, multi-document transactions incurs a greater cost when compared to single document transactions. In effect, Mongo expects that transaction scope needs to be limited to a single document for highest performance.

• Predicate-based sharding. Avoids N+1 problem and network broadcasts when running a query in high fanout scenarios. This ensures low-latency query execution, irrespective of the size of the cluster or the number of intermediate results. Reference
• Consistent production level latencies and consistent queries. Reference
• Automatic sharding
• Sharding a single predicate on the roadmap

• Providing a sharding key is mandatory
• Use of sharding key implies overheads on data modelling, indexing, and querying

MongoDB always replicates data asynchronously from primary to secondaries

Adding replication puts additional constraints on the client. Here are a couple:
Asynchronous replication to secondaries means that reads from secondaries may return data that does not reflect the state of the data on the primary.

Multi-document transactions that contain read operations must use read preference primary. All operations in a given transaction must route to the same member.

Clients using a “local” read concern can see transaction data that might eventually get rolled back.

• Jepsen-tested

Yes

• HA Cluster Setup is explained here
• HA Cluster setup is available in Community Edition

• MongoDB allows for high availability through Replica-Sets.
• The replication process depends on a special collection called “opLog”. This “opLog” needs to be configured based on users needs.
• When the primary goes down or becomes unavailable, the secondaries will determine a new primary to make available

MongoDB supports TLS/SSL to encrypt all of MongoDB's network traffic. 

Encryption at rest is also supported as an enterprise feature.

• GraphQL
• DQL (Dgraph Query Language) (Variation of GraphQL supporting advanced features)

• Context cancellation which works across clients and servers. So, a context cancellation at the client level would automatically cancel the query at all involved servers
• OpenCensus integration, which allows distributed tracing all the way from app to Dgraph cluster and back
• Open standards for query context cancellation and tracking

Runaway queries can be analyzed and killed by methods that are exposed in MongoDB. reference

• Binary format
• Both full and incremental backups to files, S3 and Google storage via Minio
• Live backups with no downtime

Reference

• Supported

• Open source version is under Apache 2.0, so free to use and modify
• Enterprise version pricing is based on the number of instances of Dgraph, not the number of cores / RAM / Disk, etc…

Yes

• Apache 2.0. GitHub
• Enterprise features are NOT Apache 2.0. But, users can still read the source
• Dgraph open source version and enterprise version provide the same performance. They’re only different in that enterprise version has more features
• Dgraph supports many open standards, like Grpc, Protocol Buffers, Go contexts, Open Census integration for distributed tracing

• HTTP/HTTPS
• gRPC
• Protocol Buffers

• JSON web tokens
• ACLs for enterprise
• Integration with LDAP on the roadmap

Multiple authentication and authorization mechanisms supported. Certain mechanisms are only supported in MongoDB Enterprise including LDAP and Kerberos.

reference

• Dgraph’s drivers use gRPC not REST
• Any GraphQL compatible client can be used
• Dgraph’s supported drivers are the same as Neo4J’s supported drivers: Java, JavaScript , Go, Python, .Net
• Dgraph’s unofficial drivers are: Rust, Dart, Elixir

• Dgraph Cloud (shared cluster)
• Dgraph Cloud (dedicated cluster)

• Shortest k-paths
• Edge traversal limit to determine cycles in graphs
• Others requested from community listed here

• Using BulkLoader or LiveLoader, Dgraph can read the data as is with no modification needed
• Supported data formats are JSON and RDF
• Exporting database is explained here

• Supported