JPH04336340A - Disk cache access control system - Google Patents

Abstract

PURPOSE:To effectively utilize a disk cache by adding disk cache control information in kind units of blocks to the data base description of an application program, and controlling the disk cache while referring to the information in a data base access routine. CONSTITUTION:This system has an external storage device 1 including plural magnetic disks 2, the data base access routine 4 which takes necessary data out by controlling the external storage device 1 and disk cache 3 at access requests from the disk cache 3 and application program, and the application program 6 which includes input/output device allocation information (with which I/O with the cache and I/O without the cache are possible) and the disk cache control information.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk cache access control system.

0002

2. Description of the Related Art Conventionally, when a disk cache function is provided to this type of database, only files can be made resident in the disk cache.

0003

[Problems to be Solved by the Invention] The conventional database disk cache resident described above can only be done in file units, and all data is stored in the cache regardless of the access frequency, which is larger than the disk cache capacity. This was not possible with files.

0004

[Means for Solving the Problems] The disk cache access control method of the present invention adds disk cache control information for each block type to the file description of a database of an application program, and the database access routine It is configured to control cached I/O and non-cached I/O by referring to disk cache control information.

Further, in the disk cache access control system of the present invention, the disk cache control information is configured so that frequently accessed blocks are made to reside in the disk cache.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings.

FIG. 1 is an explanatory diagram showing an embodiment of a database disk cache access control system. In the figure, the disk cache access control method controls an external storage device 1 including a plurality of magnetic disks 2, a disk cache 3, and the external storage device 1 and the disk cache 3 according to an access request from an application program to obtain necessary data. Database access routine 4 that retrieves the input/output device allocation information on the computer OS (this information allows cached
(capable of cacheless I/O) 5, and an application program 6 containing disk cache control information.

First, the application program 6 specifies in disk cache control information which part of the file is to be made resident in the disk cache. here,
Assume that the index section and data section are specified to be resident. After a file is opened, when a data access request is issued by the application program 6, the database access routine 4 refers to the disk cache control information on the application program 6 and specifies the use of the disk cache (here, the index section and data section). If there is a resident designation), use of the disk cache is declared for the information area corresponding to the external storage device 1 of the input/output device allocation information 5 on the computer OS.

Next, when accessing the index section stored in the external storage device 1, the database access routine 4 refers to the disk cache control information of the application program 6, and if the index section is designated as resident, the database access routine 4 accesses the index section stored in the external storage device 1. The contents are stored in the disk cache 3 block by block. At this time, if the key to be searched already exists on the disk cache 3, the key is not stored in the disk cache 3, but the index data on the disk cache 3 is used.

After the search is completed, the database access routine 4 accesses the data stored in the external storage device 1. At this time, the disk cache control information on the application program 6 is referred to again, and if the data portion is designated as resident, the contents accessed from the external storage device 1 are stored in the disk cache 3 in blocks. If the corresponding data already exists on the disk cache 3, the data on the disk cache 3 is not stored in the disk cache 3, but the data on the disk cache 3 is used.

[0011] When storing accessed contents in the disk cache 3, mapping is performed in units of blocks using block numbers. As a result, even if there are multiple magnetic disks 2,
If files are created with storage in the disk cache 3 in mind, only frequently accessed data will remain, allowing the disk cache 3 to be used effectively.

0012

As explained above, the present invention adds disk cache control information for each block type to the database description of an application program, and controls the disk cache while referring to this information in the database access routine. This has the effect of making effective use of disk cache. This is particularly effective when applied to large-capacity databases.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention.

[Explanation of symbols]

1 External storage device 2 Magnetic disk 3 Disk cache 4 Database access routine 5 I/O device allocation information

Claims (2)

[Claims] 1. Disk cache control information for each block type is added to the file description of a database of an application program, and the access routine of the database refers to the disk cache control information of the application program to access the cached I/O.
O. A disk cache access control method characterized by controlling I/O without cache. 2. The disk cache access control method according to claim 1, wherein the disk cache control information is configured so that frequently accessed blocks are made to reside in the disk cache.