System Global Area
Encyclopedia
In the database management system
s developed by the Oracle Corporation
, the System Global Area (SGA) forms the part of the RAM
shared by all the processes belonging to a single Oracle database
instance. The SGA contains all information necessary for the instance operation.
In general, the SGA consists of the following:
Database management system
A database management system is a software package with computer programs that control the creation, maintenance, and use of a database. It allows organizations to conveniently develop databases for various applications by database administrators and other specialists. A database is an integrated...
s developed by the Oracle Corporation
Oracle Corporation
Oracle Corporation is an American multinational computer technology corporation that specializes in developing and marketing hardware systems and enterprise software products – particularly database management systems...
, the System Global Area (SGA) forms the part of the RAM
Ram
-Animals:*Ram, an uncastrated male sheep*Ram cichlid, a species of freshwater fish endemic to Colombia and Venezuela-Military:*Battering ram*Ramming, a military tactic in which one vehicle runs into another...
shared by all the processes belonging to a single Oracle database
Oracle database
The Oracle Database is an object-relational database management system produced and marketed by Oracle Corporation....
instance. The SGA contains all information necessary for the instance operation.
In general, the SGA consists of the following:
- dictionary cacheCacheIn computer engineering, a cache is a component that transparently stores data so that future requests for that data can be served faster. The data that is stored within a cache might be values that have been computed earlier or duplicates of original values that are stored elsewhere...
: information about data dictionaryData dictionaryA data dictionary, or metadata repository, as defined in the IBM Dictionary of Computing, is a "centralized repository of information about data such as meaning, relationships to other data, origin, usage, and format." The term may have one of several closely related meanings pertaining to...
tableTable (database)In relational databases and flat file databases, a table is a set of data elements that is organized using a model of vertical columns and horizontal rows. A table has a specified number of columns, but can have any number of rows...
s, such as information about account, datafile, segment, extent, table and privileges - redo log buffer: containing information about committed transactions that the database has not yet written to online redo log files
- the buffer_cache or "database buffer cache": holds copies of data blocks read from datafiles
- shared pool, the cache of parseParsingIn computer science and linguistics, parsing, or, more formally, syntactic analysis, is the process of analyzing a text, made of a sequence of tokens , to determine its grammatical structure with respect to a given formal grammar...
d commonly-used SQLSQLSQL is a programming language designed for managing data in relational database management systems ....
statements, and also the data-dictionary cache containing tables, viewView (database)In database theory, a view consists of a stored query accessible as a virtual table in a relational database or a set of documents in a document-oriented database composed of the result set of a query or map and reduce functions...
s and triggers - Java pool, for parsing JavaJava (programming language)Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...
statements. - large pool (including the User Global Area (UGA))