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Arctic URI

The URI provided to an Arctic instance is used to specify the storage backend and its configuration.


The S3 URI connection scheme has the form s3(s)://<s3 end point>:<s3 bucket>[?options].

Use s3s as the protocol if communicating with a secure endpoint.

Options is a query string that specifies connection specific options as <name>=<value> pairs joined with &.

Available options for S3:

Option Description
port port to use for S3 connection
region S3 region
use_virtual_addressing Whether to use virtual addressing to access the S3 bucket
access S3 access key
secret S3 secret access key
path_prefix Path within S3 bucket to use for data storage
aws_auth If true, authentication to endpoint will be computed via AWS environment vars/config files. If no options are provided aws_auth will be assumed to be true.

Note: When connecting to AWS, region can be automatically deduced from the endpoint if the given endpoint specifies the region and region is not set.


The Azure URI connection scheme has the form azure://[options]. It is based on the Azure Connection String, with additional options for configuring ArcticDB. Please refer to for more details.

options is a string that specifies connection specific options as <name>=<value> pairs joined with ; (the final key value pair should not include a trailing ;).

Additional options specific for ArcticDB:

Option Description
Container Azure container for blobs
Path_prefix Path within Azure container to use for data storage
CA_cert_path (Non-Windows platform only) Azure CA certificate path. If not set, default path will be used. Note: For Linux distribution, default path is set to /etc/pki/ca-trust/extracted/pem/tls-ca-bundle.pem. If the certificate cannot be found in the provided path, an Azure exception with no meaningful error code will be thrown. For more details, please see here. For example, Failed to iterate azure blobs 'C' 0:.

Default certificate path in various Linux distributions:
/etc/ssl/certs/ca-certificates.crt for Debian/Ubuntu/Gentoo etc.
/etc/pki/tls/certs/ca-bundle.crt for Fedora/RHEL 6
/etc/ssl/ca-bundle.pem for OpenSUSE
/etc/pki/tls/cacert.pem for OpenELEC
/etc/pki/ca-trust/extracted/pem/tls-ca-bundle.pem for CentOS/RHEL 7
/etc/ssl/cert.pem for Alpine Linux

For Windows user, CA_cert_path cannot be set. Please set CA certificate related option on Windows setting. For details, you may refer to

Exception: Azure exceptions message always ends with {AZURE_SDK_HTTP_STATUS_CODE}:{AZURE_SDK_REASON_PHRASE}.

Please refer to for more details of provided status codes.

Note that due to a bug in Azure C++ SDK (, Azure may not give meaningful status codes and reason phrases in the exception. To debug these instances, please set the environment variable export AZURE_LOG_LEVEL to 1 to turn on the SDK debug logging.


The LMDB connection scheme has the form lmdb:///<path to store LMDB files>[?options].

Options is a query string that specifies connection specific options as <name>=<value> pairs joined with &.

Option Description
map_size LMDB map size (see here). String. Supported formats are:

"150MB" / "20GB" / "3TB"

The only supported units are MB / GB / TB.

On Windows and MacOS, LMDB will materialize a file of this size, so you need to set it to a reasonable value that your system has room for, and it has a small default (order of 1GB). On Linux, this is an upper bound on the space used by LMDB and the default is large (order of 100GB).

Example connection strings are lmdb:///home/user/my_lmdb or lmdb:///home/user/my_lmdb?map_size=2GB.


The in-memory connection scheme has the form mem://.

The storage is local to the Arctic instance.