Working with Databases

Database Methods

The following methods are available to manage databases via JavaScript. Please note that several of these methods can be used from the _system database only.

Name

return the database name db._name()

Returns the name of the current database as a string.

Examples

  1. arangosh> require("@arangodb").db._name();

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  1. _system

ID

return the database id db._id()

Returns the id of the current database as a string.

Examples

  1. arangosh> require("@arangodb").db._id();

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  1. 1

Path

return the path to database files db._path()

Returns the filesystem path of the current database as a string.

Examples

  1. arangosh> require("@arangodb").db._path();

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  1. none

isSystem

return the database type db._isSystem()

Returns whether the currently used database is the _system database. The system database has some special privileges and properties, for example, database management operations such as create or drop can only be executed from within this database. Additionally, the _system database itself cannot be dropped.

Properties

return the path to database files db._properties()

Returns the properties of the current database as an object with the following attributes:

  • id: the database id
  • name: the database name
  • isSystem: the database type
  • path: the path to database files
  • sharding: the sharding method to use for new collections (Cluster only)
  • replicationFactor: default replication factor for new collections (Cluster only)
  • writeConcern: a shard will refuse to write if less than this amount of copies are in sync (Cluster only)

Examples

  1. arangosh> require("@arangodb").db._properties();

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  1. { 
  2.   "id" : "1", 
  3.   "name" : "_system", 
  4.   "isSystem" : true, 
  5.   "sharding" : "", 
  6.   "replicationFactor" : 2, 
  7.   "writeConcern" : 1, 
  8.   "path" : "" 
  9. }

Use Database

change the current database db._useDatabase(name)

Changes the current database to the database specified by name. Note that the database specified by name must already exist.

Changing the database might be disallowed in some contexts, for example server-side actions (including Foxx).

When performing this command from arangosh, the current credentials (username and password) will be re-used. These credentials might not be valid to connect to the database specified by name. Additionally, the database only be accessed from certain endpoints only. In this case, switching the database might not work, and the connection / session should be closed and restarted with different username and password credentials and/or endpoint data.

List Databases

return the list of all existing databases db._databases()

Returns the list of all databases. This method can only be used from within the _system database.

Create Database

create a new database db._createDatabase(name, options, users)

Creates a new database with the name specified by name. There are restrictions for database names (see DatabaseNames).

Note that even if the database is created successfully, there will be no change into the current database to the new database. Changing the current database must explicitly be requested by using the db._useDatabase method.

The options attribute can be used to set defaults for collections that will be created in the new database (Cluster only):

  • sharding: The sharding method to use. Valid values are: "" or "single". Setting this option to "single" will enable the OneShard feature in the Enterprise Edition.
  • replicationFactor: Default replication factor. Special values include "satellite", which will replicate the collection to every DB-Server, and 1, which disables replication.
  • writeConcern: how many copies of each shard are required to be in sync on the different DB-Servers. If there are less then these many copies in the cluster a shard will refuse to write. The value of writeConcern can not be larger than replicationFactor.

The optional users attribute can be used to create initial users for the new database. If specified, it must be a list of user objects. Each user object can contain the following attributes:

  • username: the user name as a string. This attribute is mandatory.
  • passwd: the user password as a string. If not specified, then it defaults to an empty string.
  • active: a boolean flag indicating whether the user account should be active or not. The default value is true.
  • extra: an optional JSON object with extra user information. The data contained in extra will be stored for the user but not be interpreted further by ArangoDB.

If no initial users are specified, a default user root will be created with an empty string password. This ensures that the new database will be accessible via HTTP after it is created.

You can create users in a database if no initial user is specified. Switch into the new database (username and password must be identical to the current session) and add or modify users with the following commands.

  1. require("@arangodb/users").save(username, password, true);
  2. require("@arangodb/users").update(username, password, true);
  3. require("@arangodb/users").remove(username);

Alternatively, you can specify user data directly. For example:

  1. db._createDatabase("newDB", {}, [{ username: "newUser", passwd: "123456", active: true}])

Those methods can only be used from within the _system database.

Drop Database

drop an existing database db._dropDatabase(name)

Drops the database specified by name. The database specified by name must exist.

Note: Dropping databases is only possible from within the _system database. The _system database itself cannot be dropped.

Databases are dropped asynchronously, and will be physically removed if all clients have disconnected and references have been garbage-collected.

Compact

Introduced in: v3.5.6, v3.6.7, v3.7.3

compact the entire data, for all databases db._compact(options)

This command can be used to reclaim disk space after substantial data deletions have taken place. It requires superuser access.

The optional options attribute can be used to get more control over the compaction. The following attributes can be used in it:

  • changeLevel: whether or not compacted data should be moved to the minimum possible level. The default value is false.
  • compactBottomMostLevel: whether or not to compact the bottommost level of data. The default value is false.

This command can cause a full rewrite of all data in all databases, which may take very long for large databases. It should thus only be used with care and only when additional I/O load can be tolerated for a prolonged time.

Engine

retrieve the storage engine type used by the server db._engine()

Returns the name of the storage engine in use (mmfiles or rocksdb), as well as a list of supported features such as types of indexes.

Engine statistics

retrieve statistics related to the storage engine db._engineStats()

Returns some statistics related to the storage engine activity, including figures about data size, cache usage, etc.

Get the Version of ArangoDB

db._version()

Returns the server version string. Note that this is not the version of the database.

Examples

  1. arangosh> require("@arangodb").db._version();

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  1. 3.8.1