Index locking

In databases an index is a data structure, part of the database, used by a database system to effectively navigate access to user data. Index data are system data distinct from user data, and consist primarily of pointers. Changes in a database (by insert, delete, or modify operations), may require indexes to be updated to maintain accurate user data accesses.Index locking is a technique used to maintain index integrity. A portion of an index is locked during a database transaction when this portion is being accessed by the transaction as a result of attempt to access related user data. Additionally, special database system transactions (not user-invoked transactions) may be invoked to maintain and modify an index, as part of a system's self-maintenance activities. When a portion of an index is locked by a transaction, other transactions may be blocked from accessing this index portion (blocked from modifying, and even from reading it, depending on lock type and needed operation). Index Locking Protocol guarantees that Phantom Phenomenon won't occur. Index locking protocol states:

Index

An index is an indirect shortcut derived from and pointing into a greater volume of values, data, information or knowledge. Index may refer to:

Business

Publishing

MC2 France

MC2 France is a French software company that develops and publishes video games focusing on adventure games. It was formed in 2003 when Emmanuel Olivier merged Microïds and Wanadoo Edition. In late 2009 all of the licences associated with the company were purchased by Anuman Interactive, and currently the Microïds brand is used.

Brand history

Microïds

Microïds was founded in 1985 by Elliot Grassiano. For the first 10 years, Microïds was a development house, but in 1995 it expanded into publishing and distribution as well.

Microïds is well known for the development of the adventure games including Syberia, Syberia II, Post Mortem and its sequel Still Life. Other notable games that Microïds has produced include Far Gate and the Nicky Boum series of action games for the Commodore Amiga.

On 23 November 2009 Anuman Interactive announced that they were acquiring the mark of and all the associated licences of Microïds. The Microïds deal with MC2 was completed on 1 January 2010.

MC2 France

Database index

A database index is a data structure that improves the speed of data retrieval operations on a database table at the cost of additional writes and storage space to maintain the index data structure. Indexes are used to quickly locate data without having to search every row in a database table every time a database table is accessed. Indexes can be created using one or more columns of a database table, providing the basis for both rapid random lookups and efficient access of ordered records.

An index is a copy of select columns of data from a table that can be searched very efficiently that also includes a low-level disk block address or direct link to the complete row of data it was copied from. Some databases extend the power of indexing by letting developers create indices on functions or expressions. For example, an index could be created on upper(last_name), which would only store the upper case versions of the last_name field in the index. Another option sometimes supported is the use of partial indices, where index entries are created only for those records that satisfy some conditional expression. A further aspect of flexibility is to permit indexing on user-defined functions, as well as expressions formed from an assortment of built-in functions.