A database is an organized collection of ,
today typically in digital form. The data are typically organized to
model relevant aspects of reality (for example, the availability of
rooms in hotels), in a way that supports processes requiring this
information (for example, finding a hotel with vacancies).
The term database is correctly applied to the data and their supporting , and not to the (DBMS). The database data collection with DBMS is called a .
The term database system implies that the data is managed to some level of quality (measured in terms of accuracy,
availability, usability, and resilience) and this in turn often implies
the use of a general-purpose database management system (DBMS). A general-purpose DBMS is typically a complex
system that meets many usage requirements, and the databases that it
maintains are often large and complex. The utilization of databases is
now so widespread that virtually every technology and product relies on
databases and DBMSs for its development and commercialization, or even
may have such software embedded in it. Also, organizations and
companies, from small to large, depend heavily on databases for their
operations.
Well known DBMSs include , , , , , , and . A database is not generally across different DBMS, but different DBMSs can to some degree by using like and together to support a single application. A DBMS also needs to provide effective execution to properly support (e.g., in terms of , , and security) as many as needed.
Database type examples （）
The following are examples of various database types. Some of them
are not main-stream types, but most of them have received special
attention (e.g., in research) due to end-user requirements. Some exist
as specialized DBMS products, and some have their functionality types
incorporated in existing general-purpose DBMSs.
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An
active database is a database that includes an
event-driven architecture which can respond to conditions both inside
and outside the database. Possible uses include security monitoring,
alerting, statistics gathering and authorization.
Most modern relational databases include active database features in the form of .
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A
Cloud database is a database that relies on .
Both the database and most of its DBMS reside remotely, "in the cloud,"
while its applications are both developed by programmers and later
maintained and utilized by (application's) end-users through a and . More and more such database products are emerging, both of new vendors and by virtually all established database vendors.
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Data warehouses archive data from operational databases and often
from external sources such as market research firms. Often operational
data undergoes transformation on its way into the warehouse, getting
summarized, anonymized, reclassified, etc. The warehouse becomes the
central source of data for use by managers and other end-users who may
not have access to operational data. For example, sales data might be
aggregated to weekly totals and converted from internal product codes to
use so that it can be compared with data. Some basic and essential components of data warehousing include retrieving, analyzing, and data, transforming,loading and managing data so as to make it available for further use.
Operations in a data warehouse are typically concerned with bulk
data manipulation, and as such, it is unusual and inefficient to target
individual rows for update, insert or delete. Bulk native loaders for
input data and bulk SQL passes for aggregation are the norm.
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The definition of a
distributed database is broad, and may be
utilized in different meanings. In general it typically refers to a
modular DBMS architecture that allows distinct DBMS instances to
cooperate as a single DBMS over processes, computers, and sites, while
managing a single database distributed itself over multiple computers,
and different sites.
Examples are databases of local work-groups and departments at
regional offices, branch offices, manufacturing plants and other work
sites. These databases can include both segments shared by multiple
sites, and segments specific to one site and used only locally in that
site.
- Document-oriented database
A document-oriented database is a computer program designed for
storing, retrieving, and managing document-oriented, or semi structured
data, information. Document-oriented databases are one of the main
categories of so-called NoSQL databases and the popularity of the term
"document-oriented database" (or "document store") has grown with the
use of the term NoSQL itself.
Utilized to conveniently store, manage, edit and retrieve documents.
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An
embedded database system is a DBMS which is tightly integrated with an
that requires access to stored data in a way that the DBMS is “hidden”
from the application’s end-user and requires little or no ongoing
maintenance. It is actually a broad technology category that includes
DBMSs with differing properties and target markets. The term "embedded
database" can be confusing because only a small subset of embedded
database products is used in such as and devices.
These databases consist of data developed by individual end-users.
Examples of these are collections of documents, spreadsheets,
presentations, multimedia, and other files. Several products exist to
support such databases. Some of them are much simpler than full fledged
DBMSs, with more elementary DBMS functionality (e.g., not supporting
multiple concurrent end-users on a same database), with basic
programming interfaces, and a relatively small "foot-print" (not much
code to run as in "regular" general-purpose databases). However, also
available general-purpose DBMSs can often be used for such purpose, if
they provide basic user-interfaces for straightforward database
applications (limited query and data display; no real programming
needed), while still enjoying the database qualities and protections
that these DBMSs can provide.
- Federated database and multi-database
Main articles: and
A
federated database is an integrated database that comprises
several distinct databases, each with its own DBMS. It is handled as a
single database by a (FDBMS), which transparently integrates multiple autonomous DBMSs, possibly of different types (which makes it a ), and provides them with an integrated conceptual view. The constituent databases are interconnected via , and may be geographically decentralized.
Sometime the term
multi-database is used as a synonym to
federated database, though it may refer to a less integrated (e.g.,
without an FDBMS and a managed integrated schema) group of databases
that cooperate in a single application. In this case typically for distribution is used which typically includes an atomic commit protocol (ACP), e.g., the , to allow (vs. local transactions confined to a single DBMS) across the participating databases.
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A
graph database is a kind of NoSQL database that uses
with nodes, edges, and properties to represent and store information.
General graph databases that can store any graph are distinct from
specialized graph databases such as and .
The
can be thought of as a database, albeit one spread across millions of
independent computing systems. Web browsers "process" this data one page
at a time, while and other software provide the equivalent of database indexes to support search and other activities.
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In a
Hypertext database, any word or a piece of text
representing an object, e.g., another piece of text, a picture, or a
film, can be linked to that object. Hypertext databases are particularly
useful for organizing large amounts of disparate information. For
example they are useful for maintaining online .
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An
in-memory database (IMDB; also
main memory database or
MMDB) is a database that primarily resides in ,
but typically backed-up by non-volatile computer data storage. Main
memory databases are faster than disk databases. Accessing data in
memory reduces the I/O reading activity when, for example, querying the
data. In applications where response time is critical, such as
telecommunications network equipment, main memory databases are often
used.
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A
knowledge base (abbreviated
KB,
kb or Δ
) is a special kind of database for , providing the means for the computerized collection, organization, and of . Also a collection of data representing problems with their solutions and related experiences.
These databases store detailed data about the operations of an
organization. They are typically organized by subject matter, process
relatively high volumes of updates using . Essentially every major organization on earth uses such databases. Examples include
customer databases
that record contact, credit, and demographic information about a
business' customers, personnel databases that hold information such as
salary, benefits, skills data about employees, Enterprise resource
planning that record details about product components, parts inventory,
and financial databases that keep track of the organization's money,
accounting and financial dealings.
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A
parallel database, run by a parallel DBMS, seeks to improve performance through for tasks such as loading data, building indexes and evaluating queries. Parallel databases improve processing and speeds by using multiple (CPUs) (including ) and
in parallel. In parallel processing, many operations are performed
simultaneously, as opposed to serial, sequential processing, where
operations are performed with no time overlap.
The major parallel DBMS architectures (which are induced by the underlying architecture are:
- , where multiple processors share the main memory space, as well as other data storage.
- Shared disk architecture, where each processing unit
(typically consisting of multiple processors) has its own main memory,
but all units share the other storage.
- , where each processing unit has its own main memory and other storage.
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If a DBMS system responses users' request in a given time period, it can be regarded as a real time database.
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A spatial database can store the data with multidimensional features.
The queries on such data include location based queries, like "where is
the closest hotel in my area".
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A temporal database is a database with built-in time aspects, for
example a temporal data model and a temporal version of Structured Query
Language (SQL). More specifically the temporal aspects usually include
valid-time and transaction-time.
- Unstructured-data database
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An unstructured-data database is intended to store in a manageable
and protected way diverse objects that do not fit naturally and
conveniently in common databases. It may include email messages,
documents, journals, multimedia objects etc. The name may be misleading
since some objects can be highly structured. However, the entire
possible object collection does not fit into a predefined structured
framework. Most established DBMSs now support unstructured data in
various ways, and new dedicated DBMSs are emerging.
