Data warehousing software is used to design, build, manage, implement, and improve data warehouses, repositories of electronically-stored data. Unlike operational systems, which support only routine transaction processing, data warehouses are designed for use with business intelligence (BI) tools. These applications, which include data warehousing software, enable users to do more than load and retrieve data. Data warehousing systems facilitate the creation of a data dictionary and provide utilities for managing metadata. The data dictionary describes a database or group of databases, and is an important component of a database management system (DBMS). Meta data or meta information describes individual database items and defines their structure or schema. Business intelligence monitoring is an important part of administering a data warehouse with data warehousing software. Typically, online analytical processing (OLAP) is used to reveal trends and statistics that are not immediately apparent from retrieved data. Administrative features may include data mining and visualization, embedded data movement and transformation, modeling and design tools, and unstructured data analysis. Typically, data warehousing software supports standard data mining models such as associations, classification, clustering, and prediction. Embedded data movement and transformation provides control flows that can support conditional processing and parallel processing. Programmatic support for data warehouse analytic structures is also available. Modeling and design tools are used for change management, compliance analysis, impact analysis, and validation. Unstructured data analysis uses two basic annotators: dictionary extractors and pattern-based extractors. Data warehousing software enables businesses and other organizations to implement scalable, flexible, high-performance data warehousing solutions. Data warehouse applications that feature a distributed architecture are highly-scalable products that can process both relational and XML data. Relational data is stored in databases that group items according to common attributes in a data set. Extensible markup language (XML) is a general-purpose specification for creating custom markup languages, and is used in the exchange of a data on the Web. Advanced features for data warehousing software includes data partitioning, multi-dimensional clustering, and materialized query tables (MQT). Data warehousing software with backup capabilities, row compression, and rapid data redistribution is also available. Some applications also manage workloads based on user priorities and prevent runaway queries.