Doradus Spider Databases

[Table of Contents](https://github.com/dell-oss/Doradus/wiki/Spider Databases: Table-of-Contents) | Next

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This document describes the Doradus Spider database, which is a Doradus server configured to use the Spider storage service to manage data. The Spider storage manager provides flexible indexing and update features that benefit specific types of applications. This document describes the unique features of the Spider service, including its data model, query language, and REST API commands.

Doradus Spider builds upon the Doradus core data model and query language (DQL). This document provides an overview of these topics and provides Spider-specific examples. The following documents are also available:

• [Doradus OLAP Databases](https://github.com/dell-oss/Doradus/wiki/Doradus OLAP Databases): Describes the features, data model extensions, and REST commands specific to Doradus OLAP, which is an alternative storage service to Doradus Spider.

• Doradus Administration: Describes how to install and configure Doradus for various deployment scenarios, and operational topics such as security, monitoring, and the JMX API.

This document is organized into the following sections:

• Architecture: An overview of the Doradus architecture. The Doradus OLAP and Doradus Spider databases are compared.

• Spider Database Overview: An overview of the Spider database including its unique features and the type of applications it is best suited for.

• Spider Data Model: Describes core Doradus data model concepts and describes the extensions specific to Doradus Spider.

• Doradus Query Language (DQL): A detailed description of DQL concepts including extensions specific to Doradus Spider databases.

• Spider Object Queries: Describes the Object Query type including parameters and output results in XML and JSON.

• Spider Aggregate Queries: Describes the Aggregate Query type including parameters and output results in XML and JSON.

• Spider REST Commands: Describes the REST commands supported by Spider databases for application management, updates, queries, and task management.

Recent Changes

The following changes were made to reflect new features for the v2.3 release:

• In object queries, the order parameter (&o) now supports multiple sort fields. Example: &o=LastName,FirstName.
• The application schema key property is now optional. A key is only needed in a schema change or delete request when the applications was originally defined with a key.
• Statistics have been de-implemented since Doradus OLAP provides a better solution for applications requiring complex aggregate queries. Statistics and related task management features have been removed from the documentation.
• In input messages, an XML element can contain characters that are considered illegal in XML by base64-encoding the element content and adding the attribute encoding="base64". In output messages, Doradus performs this encoding automatically.
• The section of schema definitions has been eliminated in favor of the application- and table-level option data-check-frequency.
• All task types other than data-aging have been eliminated, and a single GET /_tasks command is now used to query task status.
• Aggregate queries support new FIRST and LAST grouping functions, which limit group results based on group names instead of metric values.
• Doradus now supports multi-tenant operation, in which applications are owned by independent, named tenants. REST commands intended for a specific tenant must include a ?tenant URI parameter and tenant credentials via the Authorization header.