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PostgreSQL: Documentation
(postgresql.org)
reference
version-indexed PostgreSQL manuals, current and unsupported releases, browsable or PDF
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GitHub - mysql/mysql-server: MySQL Server, the world's most popular open source database, and MySQL Cluster, a real-time, open source transactional database.
(GitHub)
repo
Oracle's MySQL server and NDB Cluster sources, GPLv2 community edition
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MariaDB Foundation - MariaDB.org
(MariaDB.org)
organisation
MariaDB Foundation news on server internals: pluggable aggregates, JSON_TABLE, sponsorship; MariaDB is GPLv2
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SQLite Home Page
(sqlite.org)
tool
Self-contained C library SQL engine with no server process, public-domain source
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Firebird: The true open source database for Windows, Linux, Mac OS X and more
(Home)
tool
InterBase-lineage SQL engine for Linux, Windows and macOS; open source, commercial support ecosystem
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MonetDB
(MonetDB)
tool
column-store SQL engine for analytics and hybrid HTAP, full ACID, window functions, UDF hooks; open source
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Apache Derby
(db.apache.org)
tool
embedded Java relational database with JDBC drivers, ~3.5 MB footprint; retired read-only since Oct 2025
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H2 Database Engine (redirect)
(h2database.com)
tool
Embedded Java SQL engine, open source, runs in-process or as a standalone server
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What is SQL Server on Linux? - SQL Server
(learn.microsoft.com)
reference
running Microsoft's proprietary engine on RHEL, Ubuntu, SLES, in containers or WSL2
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CockroachDB Docs - CockroachDB
(CockroachDB)
reference
distributed SQL built to survive region failures; docs plus free Cockroach University, core source-available
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Citus Data | Distributed Postgres. At any scale.
(Citus Data)
tool
Postgres extension adding row- and schema-based sharding for scale-out; open source, free to self-manage
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Home - ClickHouse Documentation
(ClickHouse Documentation)
reference
column-store OLAP engine for analytics and warehousing, Apache-2.0; docs index and integration catalogue
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An in-process SQL OLAP database management system
(DuckDB)
tool
in-process OLAP engine querying CSV and Parquet in place and pandas frames directly, MIT licensed
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Tiger Data Documentation
(Tiger Data Docs)
reference
TimescaleDB, the PostgreSQL time-series extension: hypertables, continuous aggregates, self-run or cloud
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Low-latency time-series database on open formats | QuestDB
(QuestDB)
tool
SQL-queried time-series store aimed at high-rate ingest; Apache-2.0 core, commercial editions
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Apache Doris: Open Source, Real-Time Analytics and Search Database for the AI Era - Apache Doris
(doris.apache.org)
tool
MPP column store for sub-second SQL over logs, metrics, JSON and vectors; Apache-licensed
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DBeaver Community | Free Open-Source Database Management Tool
(dbeaver.io)
tool
cross-engine desktop SQL client; Community Edition no-cost under Apache-2.0, paid PRO alongside
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SQL Indexing and Tuning e-Book for developers: Use The Index, Luke covers Oracle, MySQL, PostgreSQL, SQL Server, ...
(use-the-index-luke.com)
tutorial
vendor-agnostic SQL indexing and query tuning; free web edition of SQL Performance Explained
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Part I. Tutorial
(PostgreSQL Documentation)
tutorial
Introductory walkthrough of relational concepts and SQL against PostgreSQL, official Part I
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SQLite In 5 Minutes Or Less
(sqlite.org)
tutorial
first steps with the sqlite3 command-line shell and the TCL binding; prebuilt binaries or build yourself
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Modern SQL: A lot has changed since SQL-92
(modern-sql.com)
reference
what the SQL standard added after SQL-92 -- CTEs, arrays, temporal -- with per-engine support tables