The reverse star schema is a

schema Schema may refer to: Science and technology * SCHEMA (bioinformatics), an algorithm used in protein engineering * Schema (genetic algorithms), a set of programs or bit strings that have some genotypic similarity * Schema.org, a web markup vocab ...

optimized for fast retrieval of large quantities of descriptive

data Data ( , ) are a collection of discrete or continuous values that convey information, describing the quantity, quality, fact, statistics, other basic units of meaning, or simply sequences of symbols that may be further interpreted for ...

. The design was derived from a warehouse

star schema In computing, the star schema or star model is the simplest style of data mart Logical schema, schema and is the approach most widely used to develop data warehouses and dimensional data marts. The star schema consists of one or more fact tables ...

, and its adaptation for descriptive data required that certain key characteristics of the classic star schema be "reversed".

Model

The relation of the central table to those in dimension tables is one-to-many, or in some cases many-to-many rather than many-to-one; the primary keys of the central table are the

foreign key A foreign key is a set of attributes in a table that refers to the primary key of another table, linking these two tables. In the context of relational databases, a foreign key is subject to an inclusion dependency constraint that the tuples ...

s in dimension tables, and the main tables are, in general, smaller than the dimension tables. Main table columns are typically the source of query constraints, as opposed to dimension tables in the classical star schema. By starting queries with the smaller table, many results are filtered out early in the querying process, thereby streamlining the entire

search path PATH is an environment variable on Unix-like operating systems, DOS, OS/2, and Microsoft Windows, specifying a set of directories where executable programs are located. In general, each executing process or user session has its own PATH setting ...

. To add further flexibility, more than one main table is allowed, with main and submain tables having a one-to-many relation. Each main table can have its own dimension tables. To provide further

query optimization Query optimization is a feature of many relational database management systems and other databases such as NoSQL and graph databases. The query optimizer attempts to determine the most efficient way to execute a given query by considering the po ...

, a data set can be partitioned into separate physical schemas on either the same

database server A database server is a server which uses a database application that provides database services to other computer programs or to computers, as defined by the client–server model. Database management systems (DBMSs) frequently provide database- ...

or different database servers.

References

{{DEFAULTSORT:Reverse star schema Data warehousing Data modeling

Model

See also

References