> ## Documentation Index
> Fetch the complete documentation index at: https://private-7c7dfe99-parallel-read-in-order-multi-part.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

> Documentation for Database Engines

# Database Engines

Database engines allow you to work with tables. By default, ClickHouse uses the [Atomic](/reference/engines/database-engines/atomic) database engine, which provides configurable [table engines](/reference/engines/table-engines/index) and an [SQL dialect](/reference/syntax).

Here is a complete list of available database engines. Follow the links for more details:

| Page | Description |
| - | - |
| [Shared](/reference/engines/database-engines/shared) | Page describing the `Shared` database engine, available in ClickHouse Cloud |
| [Atomic](/reference/engines/database-engines/atomic) | The `Atomic` engine supports non-blocking `DROP TABLE` and `RENAME TABLE` queries, and atomic `EXCHANGE TABLES`queries. The `Atomic` database engine is used by default. |
| [Replicated](/reference/engines/database-engines/replicated) | The engine is based on the Atomic engine. It supports replication of metadata via DDL log being written to ZooKeeper and executed on all of the replicas for a given database. |
| [PostgreSQL](/reference/engines/database-engines/postgresql) | Allows to connect to databases on a remote PostgreSQL server. |
| [MySQL](/reference/engines/database-engines/mysql) | Allows connecting to databases on a remote MySQL server and perform `INSERT` and `SELECT` queries to exchange data between ClickHouse and MySQL. |
| [SQLite](/reference/engines/database-engines/sqlite) | Allows to connect to SQLite databases and perform `INSERT` and `SELECT` queries to exchange data between ClickHouse and SQLite. |
| [MaterializedPostgreSQL](/reference/engines/database-engines/materialized-postgresql) | Creates a ClickHouse database with tables from PostgreSQL database. |
| [Backup](/reference/engines/database-engines/backup) | Allows to instantly attach table/database from backups in read-only mode. |
| [DataLakeCatalog](/reference/engines/database-engines/datalake) | The DataLakeCatalog database engine enables you to connect ClickHouse to external data catalogs and query open table format data |
| [Dictionary](/reference/engines/database-engines/dictionary) | The Dictionary database engine exposes configured dictionaries as read-only tables. |
| [Filesystem](/reference/engines/database-engines/filesystem) | The Filesystem database engine exposes files in a local directory as read-only tables. |
| [HDFS](/reference/engines/database-engines/hdfs) | The HDFS database engine exposes files in HDFS as read-only tables. |
| [Memory](/reference/engines/database-engines/memory) | The Memory database engine keeps database metadata and tables only for the current server session. |
| [Ordinary](/reference/engines/database-engines/ordinary) | The Ordinary database engine is a deprecated legacy engine superseded by Atomic. |
| [S3](/reference/engines/database-engines/s3) | The S3 database engine exposes objects in Amazon S3 and compatible object storage as read-only tables. |
| [URL](/reference/engines/database-engines/url) | The URL database engine exposes URL-addressed data as tables. |