Database Systems#
Reference of major DBMS products by category, with the typical query language, distribution model, and license. For data formats themselves, see Data Formats. For programming languages and ORMs, see Languages.
Relational (RDBMS)#
Product |
Vendor / Org |
License |
Notes |
|---|---|---|---|
PostgreSQL |
PGDG |
PostgreSQL |
Standard ANSI SQL+; extensions ecosystem (PostGIS, TimescaleDB, pgvector); replication. |
MySQL |
Oracle |
GPLv2 + comm. |
Most-deployed OLTP RDBMS; InnoDB engine. |
MariaDB |
MariaDB Corp. |
GPLv2 |
MySQL fork; Oracle-divergence. |
SQLite |
Public domain |
PD |
Embedded; library not server; serverless. |
Oracle Database |
Oracle |
Commercial |
Enterprise OLTP; PL/SQL; RAC clustering. |
SQL Server |
Microsoft |
Commercial |
T-SQL; Linux + Windows; Azure SQL. |
DB2 |
IBM |
Commercial |
Mainframe + LUW + i editions. |
Sybase ASE |
SAP |
Commercial |
Enterprise; T-SQL ancestor. |
Firebird |
FirebirdSQL |
IPL/IDPL |
Open-source InterBase fork. |
HSQLDB |
HSQLDB Group |
BSD |
Java-embedded SQL. |
H2 |
H2 Group |
EPL/MPL |
Java-embedded SQL. |
Derby |
Apache |
Apache 2.0 |
Java-embedded SQL. |
Cloud-managed RDBMS / DWH#
Product |
Vendor |
Notes |
|---|---|---|
Amazon RDS |
AWS |
Managed Postgres / MySQL / MariaDB / SQL Server / Oracle. |
Amazon Aurora |
AWS |
AWS-distributed Postgres-compatible / MySQL-compatible. |
Amazon Redshift |
AWS |
OLAP DWH (PostgreSQL-derived). |
Google Cloud SQL |
GCP |
Managed Postgres / MySQL / SQL Server. |
Google AlloyDB |
GCP |
Distributed Postgres-compatible. |
Google BigQuery |
GCP |
Serverless OLAP / DWH. |
Azure SQL DB |
Microsoft |
Managed SQL Server. |
Azure Synapse |
Microsoft |
OLAP DWH. |
Snowflake |
Snowflake |
Multi-cloud DWH; sep. compute/storage. |
Databricks SQL |
Databricks |
Lakehouse SQL on Delta Lake. |
Yellowbrick |
Yellowbrick |
OLAP appliance / cloud. |
Vertica |
OpenText |
Columnar OLAP. |
Teradata |
Teradata |
Enterprise DWH. |
Exadata |
Oracle |
Oracle DB on hardware. |
SAP HANA |
SAP |
In-memory OLAP+OLTP. |
NewSQL / distributed#
Product |
Org |
License |
Notes |
|---|---|---|---|
CockroachDB |
Cockroach Labs |
BSL/CCL |
Postgres-compatible; geo-distributed; Spanner-inspired. |
TiDB |
PingCAP |
Apache 2.0 |
MySQL-compatible; HTAP. |
Spanner |
Commercial |
Globally distributed; TrueTime. |
|
YugabyteDB |
Yugabyte |
Apache 2.0 |
Postgres-compatible; distributed. |
VoltDB |
Volt Active |
AGPL/Comm |
In-memory ACID. |
Vitess |
CNCF |
Apache 2.0 |
MySQL-sharding (powers YouTube). |
NuoDB |
Dassault |
Commercial |
Distributed SQL. |
Document / JSON#
Product |
Vendor |
License |
Notes |
|---|---|---|---|
MongoDB |
MongoDB |
SSPL |
BSON; replica sets; sharding. |
DocumentDB |
AWS |
Commercial |
MongoDB-API-compatible. |
Cosmos DB |
Azure |
Commercial |
Multi-model (Mongo / Cassandra / Gremlin / SQL). |
Firestore |
Commercial |
Realtime; mobile-first. |
|
Couchbase |
Couchbase |
BSL+Comm |
Document + KV; SQL++ (N1QL). |
CouchDB |
Apache |
Apache 2.0 |
Replication-first; Erlang. |
RavenDB |
Hibernating |
AGPL/Comm |
Document; .NET-first. |
ArangoDB |
ArangoDB |
Apache 2.0 |
Multi-model (doc + graph + KV). |
Key-value / cache#
Product |
Vendor / Org |
License |
Notes |
|---|---|---|---|
Redis |
Redis Ltd |
SSPL/AGPL/RSA |
In-memory KV + structures + streams; Sentinel + Cluster. |
Valkey |
Linux Found. |
BSD-3 |
Redis fork after license change. |
Dragonfly |
DragonflyDB |
BSL |
Multi-threaded Redis-compatible. |
KeyDB |
Snap |
BSD-3 |
Multi-threaded Redis fork. |
Memcached |
Open-source |
BSD |
Pure memory cache. |
DynamoDB |
AWS |
Commercial |
Serverless KV / wide-column. |
Hazelcast |
Hazelcast |
Apache 2.0 |
In-memory data grid; Java. |
Aerospike |
Aerospike |
AGPL/Comm |
Sub-millisecond KV. |
Riak KV |
TI Tokyo |
Apache 2.0 |
Dynamo-style; CAP=AP. |
LevelDB / RocksDB |
Google / Meta |
BSD |
Embedded KV libraries; LSM-tree. |
LMDB |
Symas |
OpenLDAP |
Memory-mapped B+ tree; embedded. |
BoltDB / bbolt |
etcd |
MIT |
Go embedded KV. |
Berkeley DB |
Oracle |
AGPL |
Historic embedded KV. |
Wide-column#
Product |
Vendor |
License |
Notes |
|---|---|---|---|
Cassandra |
Apache |
Apache 2.0 |
Dynamo + BigTable lineage; CQL. |
ScyllaDB |
ScyllaDB |
AGPL+Comm |
Cassandra-compatible C++ rewrite. |
HBase |
Apache |
Apache 2.0 |
BigTable on HDFS. |
Bigtable |
Commercial |
Original; powers GCP. |
|
Accumulo |
Apache |
Apache 2.0 |
Cell-level security (NSA-derived). |
Graph#
Product |
Vendor |
License |
Notes |
|---|---|---|---|
Neo4j |
Neo4j |
GPLv3+Comm |
Cypher; the standard property-graph DB. |
JanusGraph |
Apache |
Apache 2.0 |
TinkerPop / Gremlin on Cassandra / HBase / Bigtable. |
ArangoDB |
ArangoDB |
Apache 2.0 |
Multi-model. |
Dgraph |
Hypermode |
Apache 2.0 |
Distributed graph; GraphQL+. |
TigerGraph |
TigerGraph |
Commercial |
GSQL. |
Amazon Neptune |
AWS |
Commercial |
Gremlin + SPARQL + openCypher. |
Memgraph |
Memgraph |
BSL |
In-memory; Cypher. |
Stardog |
Stardog |
Commercial |
Knowledge graph (RDF + property). |
GraphDB (Ontotext) |
Ontotext |
Commercial |
RDF / SPARQL. |
Virtuoso |
OpenLink |
GPL+Comm |
Multi-model (RDF / SQL). |
Time-series#
Product |
Vendor |
License |
Notes |
|---|---|---|---|
InfluxDB |
InfluxData |
MIT/Commercial |
TSM engine; Flux + InfluxQL. |
TimescaleDB |
Timescale |
Apache 2.0+TSL |
Postgres extension. |
QuestDB |
QuestDB |
Apache 2.0 |
SQL with TS extensions. |
Prometheus |
CNCF |
Apache 2.0 |
Pull-based monitoring TSDB. |
VictoriaMetrics |
VictoriaMetrics |
Apache 2.0 |
Prometheus-compatible. |
M3DB |
Uber |
Apache 2.0 |
Distributed; Prom-compatible. |
Mimir |
Grafana |
AGPLv3 |
Multi-tenant Prom-compatible. |
Thanos |
CNCF |
Apache 2.0 |
Long-term Prom storage. |
Cortex |
CNCF |
Apache 2.0 |
Multi-tenant Prom (predecessor of Mimir). |
Druid |
Apache |
Apache 2.0 |
OLAP + TS. |
ClickHouse |
ClickHouse |
Apache 2.0 |
Columnar OLAP; popular for logs/metrics. |
TDengine |
TAOS Data |
AGPLv3 |
IoT-focused TSDB. |
Kdb+ |
KX |
Commercial |
In-memory TS; Q language; finance. |
Search / vector#
Product |
Vendor |
License |
Notes |
|---|---|---|---|
Elasticsearch |
Elastic |
AGPLv3+Elastic |
Lucene-based search; vector since 8.x. |
OpenSearch |
Linux Found. |
Apache 2.0 |
Elasticsearch fork; AWS-led. |
Solr |
Apache |
Apache 2.0 |
Lucene-based; older sibling of ES. |
Meilisearch |
Meili |
MIT |
Typo-tolerant search. |
Typesense |
Typesense |
GPLv3 |
Open-source search. |
Sphinx |
Sphinx Tech. |
GPLv2 |
Original SQL-extension search. |
Manticore |
Manticore |
GPLv2 |
Sphinx fork. |
Vespa |
Vespa.ai |
Apache 2.0 |
Yahoo-derived search + ranking. |
Qdrant |
Qdrant |
Apache 2.0 |
Vector DB; Rust. |
Weaviate |
Weaviate |
BSD-3 |
Vector DB; modular vectorisers. |
Milvus |
Zilliz / LF |
Apache 2.0 |
Vector DB; CNCF-aligned. |
Chroma |
Chroma |
Apache 2.0 |
In-process vector store. |
Pinecone |
Pinecone |
Commercial |
Managed vector. |
LanceDB |
LanceDB |
Apache 2.0 |
Embedded vector + Lance file format. |
pgvector |
pgvector |
PostgreSQL |
Vector ext for Postgres. |
Vald |
CNCF |
Apache 2.0 |
Vector DB; K8s-native. |
Object / multi-model#
Product |
Vendor |
License |
Notes |
|---|---|---|---|
SurrealDB |
SurrealDB |
BSL |
Multi-model (doc / graph / KV). |
EdgeDB |
EdgeDB |
Apache 2.0 |
Postgres-on-top object DB. |
ObjectBox |
ObjectBox |
Apache 2.0 |
Embedded object DB. |
GridDB |
Toshiba |
AGPLv3 |
IoT. |
Embedded / serverless#
Product |
Vendor |
License |
Notes |
|---|---|---|---|
SQLite |
Public domain |
PD |
The default embedded RDBMS. |
DuckDB |
DuckDB Found. |
MIT |
OLAP-in-process; SQLite for analytics. |
LMDB |
Symas |
OpenLDAP |
Memory-mapped B+ tree. |
LevelDB / RocksDB |
Google / Meta |
BSD |
LSM-tree embedded KV. |
sled |
spacejam |
Apache+MIT |
Rust embedded KV. |
TigerBeetle |
TigerBeetle |
Apache 2.0 |
Distributed financial transactions DB. |
FoundationDB |
Apple |
Apache 2.0 |
Distributed ordered KV (the layer beneath iCloud / Snowflake metadata). |
Cloudflare D1 |
Cloudflare |
Commercial |
Edge SQLite. |
PlanetScale |
PlanetScale |
Commercial |
Managed Vitess. |
OLAP / lakehouse / formats#
Engine / format |
Vendor |
License |
Notes |
|---|---|---|---|
Apache Spark |
Apache |
Apache 2.0 |
DataFrame + SQL + ML; cluster. |
Apache Flink |
Apache |
Apache 2.0 |
Streaming. |
Apache Beam |
Apache |
Apache 2.0 |
Unified batch + streaming SDK. |
Apache Iceberg |
Apache |
Apache 2.0 |
Table format; warehouse interop. |
Delta Lake |
Linux Found. |
Apache 2.0 |
Databricks-led table format. |
Apache Hudi |
Apache |
Apache 2.0 |
Upserts on data lake. |
Apache Parquet |
Apache |
Apache 2.0 |
Columnar file format. |
Apache ORC |
Apache |
Apache 2.0 |
Columnar file format (Hive). |
Apache Avro |
Apache |
Apache 2.0 |
Schema-evolved row format. |
Operator notes#
Pick by access pattern, OLTP (RDBMS), OLAP (DWH / columnar), high-write IoT (TSDB), text search (Elasticsearch / Solr / Meilisearch), vector / RAG (pgvector / Qdrant / Pinecone), graph traversal (Neo4j / Neptune), low-latency cache (Redis / KeyDB).
License drift, Redis / Elastic / MongoDB / TimescaleDB / CockroachDB have shifted to BSL / SSPL / proprietary; Valkey, OpenSearch, MariaDB are the open forks.
Cloud lock-in, managed Aurora, BigQuery, Cosmos, DynamoDB, Spanner are not portable; design escape hatches if portability matters.
Identifier collisions, “DocumentDB” exists for AWS (MongoDB-API) and Azure / Microsoft (PostgreSQL-based); always qualify.
CAP / PACELC, pick consistency vs availability vs latency tradeoffs explicitly; CockroachDB / Spanner are CP+ with low-latency commits, Cassandra / Riak are AP, classic RDBMS are CA on a single node.
References#
Database of Databases (CMU)
Designing Data-Intensive Applications, Kleppmann.
OpenTSDB, Prometheus, InfluxDB documentation.
Data Formats, data formats.
Languages, query / driver languages.