Databases Comparison
Concurrency
Control
Single-node
transactions
Distributed
transactions
Querying
Indexing
Spatial
Indexing
Full-text
search
Aggregation
Replication
Sharding
ETL
Database event
notification
Storing
binary blobs
Management Tools
DBaaS Costs
RavenDB
MongoDB
PostgreSQL
CosmosDB
Test
Optimistic
Pessimistic
Pessimistic
Optimistic
N/A
Supported
Supported*
Supported
Supported*
N/A
Ensures writes on majority of nodes
Ensures writes on majority of nodes
Two-phase commit
Multiple options
N/A
Fully fledged search-engine capabilities
Basic functionality
SQL, JSON column support
Multiple querying APIs
N/A
Lock-free, uses DSL definitions for flexibility
Sync, locks, basic functionality
Sync, locks, basic functionality, some customization
Basic functionality, index on all fields
N/A
Highly configurable, supports WKT
Supports GeoJSON
3rd-party
Supports GeoJSON
N/A
Offers all features of Lucene.Net to power rich text search
Simple tokenization
Simple tokenization with configurable dictionaries
Azure Search or 3rd-party
N/A
Declarative definition, reacts to data changes
Introduces read-locks and needs to be run manually
SQL aggregations
Limited SQL-like aggregation functions
N/A
Multiple replication strategies, high availability and load-balancing
High availability, needs special maintenance in some use cases
Active-passive only
Multiple replication strategies, high availability and load-balancing
N/A
Not supported*
Multiple sharding strategies, needs specialized services
Partitioning-based sharding*
Sharding on user-defined key
N/A
Real-time, projections and transformations
3rd-party
3rd-party
Real-time, projections, transformations, multiple types of destinations
N/A
Batch processing, projections and transformations
Basic filtering and field projection
Projections and transformations
Projections and transformations, multiple types of destinations
N/A
Supported, transactional
Supported, non-transactional
Supported, transactional
Supported
N/A
Integrated
3rd-party
3rd-party
Integrated
N/A
Flat-rate
Flat-rate with additional costs
3rd-party provider pricing
Resource Units costs - complex to figure out
N/A
Select databases to compare
Concurrency Control
RavenDB
Optimistic
Optimistic, using Vector Clock as "timestamps".
MongoDB
Pessimistic
Pessimistic, multiple granularity locks (multiple readers, single writer).
PostgreSQL
Pessimistic
Pessimistic, optionally explicit (manual) locking.
CosmosDB
Optimistic
Optimistic, using ETAGs as "timestamps".
Single-node transactions
RavenDB
Supported
Supported.
MongoDB
Supported
Supported.
PostgreSQL
Supported
Supported.
CosmosDB
Supported*
Supported.
*In CosmosDB, multi-document transaction requires running it in server-side procedure - client API support only single document changes.
Distributed Transactions
RavenDB
Ensures writes on majority of nodes
Ensures writes (assurance by consensus protocol) on majority of nodes.
MongoDB
Ensures writes on majority of nodes
Ensures writes (wait for replication) on majority of nodes.
PostgreSQL
Two-phase commit
Two-phase commit.
CosmosDB
Multiple options
Flexible, can ensure writes on majority or several more options.
Notes: RavenDB ensures majority of writes using Raft, MongoDB ensures majority of writes by waiting on async replication (for MongoDB assuming the setting writeConcern=majority).
Querying
RavenDB
Fully fledged search-engine capabilities
Allows simple and Javascript projections, facets, dynamic index declarations, loading related documents and integrated spatial and full-text search syntax.
MongoDB
Basic functionality
Allows simple (field level) projections, spatial and full-text searches.
PostgreSQL
SQL, JSON column support
Allows SQL queries, supports JSON as data columns.
CosmosDB
Multiple querying APIs
Support multiple querying APIs, such as MongoDB, SQL, Gremlin. Its own API can do queries with simple projections and filtering.
Indexing
RavenDB
Lock-free, uses DSL definitions for flexibility
Async, reacts to data changes, doesn't lock on data, can run user-code, computations and projections on field values while indexing in background.
MongoDB
Sync, locks, basic functionality
Sync, updates index as part of CRUD while locking data, indexes only field values.
PostgreSQL
Sync, locks, basic functionality, some customization
Sync, updates index as part of CRUD while locking data, indexes only field values. Can define different underlying data structures as optimization.
CosmosDB
Basic functionality, index on all fields
Reverse index on all fields in documents.
Notes: As of version 4.2, MongoDB does exclusive locking on collection at beginning and ending of indexing creation process.
Spatial Indexing
RavenDB
Highly configurable, supports WKT
Supports linear geometry, configurable indexing methods and distance units (miles/km). Supports raw longitude, latitude coordinates and standard WKT data.
MongoDB
Supports GeoJSON
Supports linear and spherical geometry, data stored as GeoJSON.
PostgreSQL
3rd-party
Supported using 3rd-party extension.
CosmosDB
Supports GeoJSON
Supports linear geometry, data stored as GeoJSON.
Notes: In PostgreSQL spatial queries are supported with PostGIS extension.
RavenDB
Offers all features of Lucene.Net to power rich text search
Highly configurable, leverages Lucene.Net to power rich text search, can use custom analyzers (value tokenizers). For example, custom analyzers can be used to implement efficient (and fast!) wildcard search (n-gram analyzers) or handling language specific characters.
MongoDB
Simple tokenization
Tokenizes by whitespace and punctuation, stemming, stopwords. Optional tokenization by wildcard.
PostgreSQL
Simple tokenization with configurable dictionaries
Configurable value tokenizers and "thesaurus" dictionaries for term mapping.
CosmosDB
Azure Search or 3rd-party
Either Azure Search/Cognitive Search or 3rd-party search engines.
Notes: With full-text indexes, MongoDB tokenization and text processing cannot be customized. PostgreSQL full-text search is not index-based, needs to run UPDATE statements to keep full-text search up-to-date.
Aggregation
RavenDB
Declarative definition, reacts to data changes
Async map/reduce over Lucene indexes, reacts to data changes, has all features of RavenDB indexes such as computations and projections.
MongoDB
Introduces read-locks and needs to be run manually
Aggregation/Map-reduce, both sync, introduce read-locks so they may stall because of long writes.
PostgreSQL
SQL aggregations
SQL aggregation (standard GROUP BY queries).
CosmosDB
Limited SQL-like aggregation functions
Limited SQL-like aggregation functions from DocumentDB SQL API.
Notes: For MongoDB, aggregation pipeline is more optimized but limited to one collection, map-reduce requires providing Javascript code for map and reduce stages. For CosmosDB, note that if you execute aggregation as part of stored procedure, there is a limit on execution time of stored procedures - your stored procedure may run into it.
Replication
RavenDB
Multiple replication strategies, high availability and load-balancing
Out of the box high availability (active-active topology), allow for multiple replication strategies (cross cluster replication, star topology replication) and load balancing between replica sets.
MongoDB
High availability, needs special maintenance in some use cases
Out of the box high availability (active-active topology), in case of even number of nodes, need "special" node.
PostgreSQL
Active-passive only
Active-passive topology only, supports either log-shipping or streaming to replicate data.
CosmosDB
Multiple replication strategies, high availability and load-balancing
Out of the box high availability and load balancing, support for custom load balancing strategies, supports active-active topology.
Notes: MongoDB and RavenDB implement Raft Consensus Protocol for maintaining replicated clusters and provide failover functionality.
Sharding
RavenDB
Not supported*
Not supported.
MongoDB
Multiple sharding strategies, needs specialized services
Multiple sharding strategies, background shard balancing, needs specialized services as part of sharding topology (query router, configuration servers).
PostgreSQL
Partitioning-based sharding*
Built-in sharding with declarative partitioning (using Foreign Data Wrapper).
CosmosDB
Sharding on user-defined key
Out of the box sharding (on user-defined key).
*For RavenDB, sharding support is scheduled for release in Q4 of 2020. For PostgreSQL, the sharding will work only if there is no brain split.
ETL
RavenDB
Real-time, projections and transformations
Supported, async transfer of data between either RavenDB -> RavenDB or RavenDB -> SQL, use Javascript to define transformation scripts.
MongoDB
3rd-party
3rd-party vendors.
PostgreSQL
3rd-party
3rd-party vendors.
CosmosDB
Real-time, projections, transformations, multiple types of destinations
Supported, transfer of data to/from CosmosDB and multiple sources. Can use Data Factory UX and properietary dataflow language to define transformation scripts.
Notes: For MongoDB and PostgreSQL ETL can be implemented with 3rd-party tools.
Database Event Notifications
RavenDB
Batch processing, projections and transformations
Supported, batch processing, declarative filtering, loading related documents and complex projections with optional calculations.
MongoDB
Basic filtering and field projection
Supported, allow filtering and simple field projection.
PostgreSQL
Projections and transformations
Supported using LISTEN/NOTIFY (event based processing).
CosmosDB
Projections and transformations, multiple types of destinations
Supported, allows sending events to client API and other destinations (like queues).
Notes: For RavenDB, filtering and projections of changed documents have the same flexible capabilities as queries, uses the same query syntax. Also, RavenDB's Data Subscription (the relevant feature) is persistant - if an offline client misses change events, they will be streamed in-order when the client comes back online.
Storing binary blobs
RavenDB
Supported, transactional
Supported, also supports multi-attachment transactions - documents and binary blobs can be changed as part of single transaction.
MongoDB
Supported, non-transactional
Supported, but doesn't support transactions.
PostgreSQL
Supported, transactional
Supported by using special column type or using Large Object feature.
CosmosDB
Supported
Supported, binary attachments can have indexable properties.
Management Tools
RavenDB
Integrated
Built-in administration web-app, fully-featured solution for database administration and devops.
MongoDB
3rd-party
3rd-party vendors.
PostgreSQL
3rd-party
3rd-party vendors.
CosmosDB
Integrated
Azure UI contains management section for CosmosDB.
DBaaS Costs
RavenDB
Flat-rate
Easy to understand flat-rate that depends on provider (AWS, Azure, GCP).
MongoDB
Flat-rate with additional costs
Flat-rate that depends on provider (AWS, Azure, GCP). Some of services like full-text search and backups have additional costs.).
PostgreSQL
3rd-party provider pricing
Depends on 3rd-party provider of PostgreSQL-as-a-service.
CosmosDB
Resource Units costs
Resource Units costs - complex to figure out.
