JPH02208750A - File access system - Google Patents

Abstract

PURPOSE:To execute an index access processing without restriction from the file system of a data file by preparing a key file designated on an application program temporarily. CONSTITUTION:A key file retrieval processing part 12 executes a retrieval to a file information management table 21 as to whether the key file designated on an application program 11 exist or not. When the fact that the key file does not exist by the key file retrieval processing part 12 is judged, a key file preparing part 13 prepares the key file designated on the application program 11. An index access processing part 14 executes an index access through the use of the key file, and a release processing part 15 releases the area of the key file prepared by the key file preparing part 13. Thus, the index access processing can be executed without being restricted by the file system of the data file.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a data search processing method, and particularly to a file access method.

[Conventional technology]

Conventionally, when accessing an index from an application program, etc., a key file had to exist in advance. Therefore, for the key file information management table in the file information management table, -
Each time, a search was performed to see if the key file to be used was registered, and if the key file to be used was not found, a key file had to be created using a utility or the like.

[Problem to be solved by the invention]

The conventional file access method described above has the disadvantage that index access processing cannot be performed unless a key file specified in advance on an application program exists.

Another drawback is that when performing index access, the file format of the data file must be an index organization file format.

In order to eliminate the above-mentioned drawbacks, it is an object of the present invention to generate a key file temporarily when the key file specified on the application program does not exist, without being aware of the file format of the data file. The purpose of this invention is to provide a file access method that allows for

[Means to solve the problem]

The present invention includes a file information management table that manages file information, and a key file that searches the file information management table to determine whether or not a key file specified on an application program actually exists. In a file access method comprising a search processing section and an index access processing section that actually accesses files using a key file.

If the key file search processing unit determines that the key file does not exist, the area required for the key file specified on the application program is determined, and free space management is performed to determine whether or not the requested area can be secured. The present invention is characterized by comprising: a key file generation unit that checks a table and generates a key file in the secured area; and a release processing unit that releases the area secured by the key file generation unit. It is something.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention.

This file access method consists of a computer 1 and an external storage device 2. The computer 1 includes an application program 11, a key file search processing section 12, a key file generation section 13, an index access processing section 14, and a release processing section 15. The external storage device 2 has a file information management table 2.
1, a free space management table 22, a data file group 23, and a key file group 24 are stored.

The key file search processing unit 12 is a processing unit that searches the file information management table 21 to determine whether a key file specified on the application program 11 exists. The key file generation unit 13 is a processing unit that generates a key file specified on the application program 11 when the key file search processing unit 12 determines that the key file does not exist. The index access processing unit 14 is a processing unit that performs index access using a key file. The release processing unit 15 is a processing unit that releases the area of the key file generated by the key file generation unit 13.

FIGS. 2(a) and 2(b) show an example of the configuration of the file information management table 21, in which the key file information management table 211 manages the key file group 24, and the data file manages the data file group 23. It consists of an information management table 212. The key file information management table 211 includes key file names, data file names, and device names.

Multiple entries are stored with key length and key position as one entry, and data file information management table 212 stores data file name, device name,
Multiple entries are stored with record length, block length, and key file name as one entry.

Figures 3(a) and 3(b) show the free space management table 2.
A specific example of 2 is shown below. It consists of a device name, free space size, free space start position, free space end position, and total free space size for each device.

Next, regarding the operation of this embodiment configured in this way,
This will be explained with reference to FIGS. 1 to 3.

When the application program 11 issues a command to perform index access, the key file search processing unit 12
are the data file name and key file name from the application program 11.

A data file search is performed in the data file information management table 212 based on the information on the key length and key position, and the application program 11 performs index access to the key file group 24 corresponding to the detected data file. Check whether the specified key file actually exists or not by referring to the key file information management table 211.0 For example, if the application program 11 selects DATA as the data file name.
2-F, KEY22-F as the key file name, key length 5. When the information of key position 0 is input, the data file information management table 212 is checked to see if DATA2-F is included in the data file name.

When DATA2-F is detected, the key file name KEY22-F is searched from the key file information management table 211. In the state shown in FIG. 2(a), as a result, KEY22-F does not exist.

If the key file search processing unit 12 determines that a key file actually exists, control is transferred to the index access processing unit 14, which performs index access using the existing key file.

Next, like KEY22-F, the key file search processing section 1
In step 2, if it is determined that the key file does not actually exist, control is transferred to the key file generation unit 13, and the data file is created in order to secure the area necessary to generate the key file specified on the application program. The information of the data file is read from the information management table 212 and the required area is determined. In this case, KEY22
-F's required area is 500 sectors.

In order to check whether the requested key file area can actually be secured on the device, the free space management table 22 is referred to, and the data file information obtained when the data file information management table 212 is referred to is Search for the area size that can secure the requested key file area from the free area size, limited to existing devices. If the area size that can secure the key file area is detected from the free area size, secure the key file,
Delete the area size for the key file area from the free area management table 22 and create the key file information management table 2.
11. Register the information of the created key file.

In this example, since the data file DATA2-F exists in the device 1, a location where 500 sectors can be secured is searched from the free space size of the device 1 in the free space management table 22. In this case, there is a free space of 10,000 sectors from sector 10,000 to sector 19,999, so at the same time, secure KEY22-F here, and at the same time, select the key file area 5 from the free space management table 22.
Delete 0o sector and create key file information management table 2
Register the KEY22-F information created in step 11 (Figure 2 (
b), see Figure 3(b)).

Next, data records are sequentially read from the data file, and based on the key position and key length information registered in the key file information management table 211, the key value and the record position in the data file are set as one entry in the index block. A key file with a one-layer structure is generated and an activation request is issued to the index access processing unit 14.

The index access processing unit 14, which has received a request from the key file generation unit 13, decodes the conditional expression from the application program 11 and uses the key file generated by the key file generation unit 13 to create the top level index block. Search for data that matches the conditional expression by descending to the second-level index block and finally to the lowest-level index block, and based on the results, search for records that match the conditional expression from the data file. is derived and the result is returned to the application program 11.

The release processing unit 15 executes the application program 11
After the processing is completed, the key file created by the key file generation unit 13 is deleted and the free space management table 2 is
The area size for the area of the key file is added to 2, and the information of the deleted key file is deleted from the key file information management table 211. Key file KEY as an example
22-F is also released by the release processing unit 15 after the processing of the application program 11 is completed, and the free space management table 22 and the key file information management table 211 are returned to their initial states (Fig. 2(a), Fig. 3(a)). a)).

Note that in the above embodiment, the file information management table 21
Although the free space management table 22 and the free space management table 22 are provided in the external storage device 2, the file information management table 21 and the free space management table 22 may be provided in the memory of the computer 1.

〔Effect of the invention〕

As explained above, the present invention has the following advantages: - By creating a key file specified on an application program from time to time, index access processing can be performed without creating a key file in advance. , and index access processing is performed without being restricted by the file format of the data file.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of an embodiment of the present invention, Fig. 2(a),
3(b) is a diagram showing the contents of the file information management table in FIG. 1, and FIGS. 3(a) and 3(b) are diagrams showing details of the free space management table in FIG. 1. 1...Electronic computer, 2...External storage device, 11...
-Application program, 12...Key file search processing unit, 13...Key file generation unit, 14
... Index access processing section, 15 ... Release processing section, 2
1...File information management table, 22...Free space management table, 23...Data file group, 24.
...Key file group, 211...Key file information management table, 212...Data file information management table.

Claims (1)

[Claims] A file information management table that manages file information, and a search performed on the file information management table to determine whether a key file specified on the application program actually exists. In a file access method that includes a key file search processing unit and an index access processing unit that uses the key file to actually access the file, when the key file search processing unit determines that the key file does not exist. Next, the area required for the key file specified on the application program is determined, the free space management table is checked to see if the requested area can be secured, and the key file is generated in the secured area. A file access method comprising: a key file generation section that performs the above operations; and a release processing section that releases an area secured by the key file generation section.