ArangoDB Server Database Options

Auto upgrade

--database.auto-upgrade

Specifying this option will make the server perform a database upgrade instead of starting the server normally. A database upgrade will first compare the version number stored in the file VERSION in the database directory with the current server version.

If the version number found in the database directory is higher than the version number the server is running, the server expects this is an unintentional downgrade and will warn about this. Using the server in these conditions is neither recommended nor supported.

If the version number found in the database directory is lower than the version number the server is running, the server will check whether there are any upgrade tasks to perform. It will then execute all required upgrade tasks and print their statuses. If one of the upgrade tasks fails, the server will exit with an error. Re-starting the server with the upgrade option will then again trigger the upgrade check and execution until the problem is fixed.

Whether or not this option is specified, the server will always perform a version check on startup. Running the server with a non-matching version number in the VERSION file will make the server refuse to start.

Directory

--database.directory directory

The directory containing the collections and datafiles. Defaults to /var/lib/arango. When specifying the database directory, please make sure the directory is actually writable by the arangod process.

You should further not use a database directory which is provided by a network filesystem such as NFS. The reason is that networked filesystems might cause inconsistencies when there are multiple parallel readers or writers or they lack features required by arangod (e.g. flock()).

directory

When using the command line version, you can simply supply the database directory as argument.

Examples

> ./arangod --server.endpoint tcp://127.0.0.1:8529 --database.directory
/tmp/vocbase

Database directory state precondition

--database.required-directory-state state

Using this option it is possible to require the database directory to be in a specific state on startup. the options for this value are:

• non-existing: database directory must not exist
• existing: database directory must exist
• empty: database directory must exist but be empty
• populated: database directory must exist and contain specific files already
• any: any directory state allowed

Force syncing of properties

force syncing of collection properties to disk--database.force-sync-properties boolean

Force syncing of collection properties to disk after creating a collection or updating its properties.

If turned off, no fsync will happen for the collection and database properties stored in parameter.json files in the file system. Turning off this option will speed up workloads that create and drop a lot of collections (e.g. test suites).

The default is true.

Maximal Journal size (MMFiles only)

--database.maximal-journal-size size

Maximal size of journal in bytes. Can be overwritten when creating a new collection. Note that this also limits the maximal size of a single document.

The default is 32MB.

Wait for sync

default wait for sync behavior--database.wait-for-sync boolean

Default wait-for-sync value. Can be overwritten when creating a new collection.

The default is false.

More advanced options

--database.throw-collection-not-loaded-error flag

Accessing a not-yet loaded collection will automatically load a collection on first access. This flag controls what happens in case an operation would need to wait for another thread to finalize loading a collection. If set to true, then the first operation that accesses an unloaded collection will load it. Further threads that try to access the same collection while it is still loading will get an error (1238, collection not loaded). When the initial operation has completed loading the collection, all operations on the collection can be carried out normally, and error 1238 will not be thrown.

If set to false, the first thread that accesses a not-yet loaded collection will still load it. Other threads that try to access the collection while loading will not fail with error 1238 but instead block until the collection is fully loaded. This configuration might lead to all server threads being blocked because they are all waiting for the same collection to complete loading. Setting the option to true will prevent this from happening, but requires clients to catch error 1238 and react on it (maybe by scheduling a retry for later).

The default value is false.

--database.replication-applier flag

Enable/disable replication applier.

If false the server will start with replication appliers turned off, even if the replication appliers are configured with the autoStart option. Using the command-line option will not change the value of the autoStart option in the applier configuration, but will suppress auto-starting the replication applier just once.

If the option is not used, ArangoDB will read the applier configuration from the file REPLICATION-APPLIER-CONFIG on startup, and use the value of the autoStart attribute from this file.

The default is true.