--- title: Databases --- ## What is a Database? A database is a container for a set of schema: [tables](/concepts/sql/table), [views](/concepts/sql/views), [triggers](/concepts/sql/triggers), [procedures](/concepts/sql/procedures), etc. In relational databases, queries within a database are optimized, while queries across multiple databases are not. A relational database management system or [RDBMS](/concepts/rdbms/) allows you to access multiple databases from a single running [server](/concepts/rdbms/server). Confusingly, "database" is also shorthand for RDBMS. Phrases like "Connect to this database" or "We run our database on AWS" refer to RDBMS, not the SQL concept of a schema container. ## How to use Databases Databases logically divide up your schema. Permissions can be applied to databases as a logical entity. When you connect a client to a running server, you can see the databases being served using the `\l` command in the `psql` shell. To use a specific database, you issue a `\c ` statement. You can also specify the database in the connection string to connect to a particular database. ## Difference between Postgres Databases and Doltgres Databases In Doltgres, databases act like they do in Postgres. ## Interaction with Doltgres Version Control In Doltgres, each database has its own commit graph. So, Doltgres version control is limited to a single database. You cannot commit changes across multiple databases in a single commit. You cannot share a log across multiple databases. Branches cannot be made across databases. Doltgres databases are the unit of sharing. Clone, push, pull, and fetch act on individual databases. Thus, to create a copy of multiple databases, you must clone from multiple remotes. The only SQL statement not versioned in Doltgres is `DROP DATABASE`. This statement deletes the Doltgres database on disk, removing the database and all of its history. `DROP DATABASE` works this way for SQL tool compatibility as it is common for import tools to issue a drop database to clear all database state before an import. Doltgres implements [remotes](/concepts/git/remotes) like in Git so you can maintain an offline copy for backup using clone, fetch, push, and pull. Maintaining a remote copy allows you to restore in the case of an errant `DROP DATABASE` query.