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An indexed file is a computer file with an index that allows easy random access to any record given its file key. The key must be such that it uniquely identifies a record. If more than one index is present the other ones are called ''alternate indexes''. The indexes are created with the file and maintained by the system. Support for indexed files is built into COBOL〔1 VS COBOL II Application Programming Language Reference, Release 4, Eighth Edition (March 1993), IBM Corporation, Department J58, Copyright International Business Machines Corporation 1984, 1993. pp. 67-73〕 and PL/I. Other languages with more limited I/O facilities such as C support indexed files through add-on packages in a runtime library such as C-ISAM.〔(【引用サイトリンク】title=Informix C-ISAM )〕 The COBOL language supports indexed files with the following command in the FILE CONTROL sectionORGANIZATION IS INDEXEDIn recent systems relational databases are often used in place of indexed files. == See also == *B-trees *Hash table *Data set (IBM mainframe) *Legacy system *dbm also X/Open ndbm and GNU gdbm *Berkeley DB 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「indexed file」の詳細全文を読む スポンサード リンク
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