JPH04114244A - File reading system - Google Patents

Abstract

PURPOSE:To shorten time for reading an arbitrary record by storing pointers showing the existent positions of all the records in the form of a table in the ascending order of records on the memory of a computer. CONSTITUTION:When the instruction of declaring the usage of a file (such as a file open instruction or the like) is issued to an external storage device driver 3, the driver 3 secures a table area 5 on a memory 4 of a computer 1. Simultaneously, the driver 3 reads a preceding pointer part 7 and a next pointer part 8 of all the records in the file on an external storage device 2, edits them, prepares a pointer table showing the existent positions in the ascending order of records from the first record to the final record and stores the table in the table area 5 on the memory 4. Thus, since the pointers showing the existent positions of all the records are stored in the form of the table in the ascending order of records on the memory 4 of the computer 1, time for reading the arbitrary record of the file is sharply shortened by a file editing system having the pointers showing the existent positions of records before and behind the arbitrary record.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a file reading method for an external storage device, and in particular to a method for reading a file using a file organization method having pointers indicating the locations of records before and after an arbitrary record. Regarding the reading method.

[Conventional technology]

Conventionally, in the organization of this type of file, in order to easily add, delete, and rearrange records, each record consists of a data section and a pointer section that indicates the location of the preceding and succeeding records.

Conventionally, records of this type of file are read by determining the location of the previous or next record using the pointer section of the record, and reading this.

Here, a conventional file reading method will be explained with reference to the drawings.

FIG. 2 is a diagram showing the structure of records of a file.

In FIG. 2, the records of the file include a data section 6 that actually stores data, a previous pointer section 7 that stores the location of the record before this record when these records are arranged in ascending order, and a previous pointer section 7 that stores the location of the record before this record when these records are arranged in ascending order. , and a next pointer section 8 that stores the location of the record after this record.

And when configuring a file with this record,
It is characterized by the ability to easily add, delete, and rearrange records.

For example, to insert a new record between the first records from the beginning, the new record itself is arbitrarily written in an empty area of the file, and the previous pointer part of the new record is 7.
By applying the and next pointer parts 8 to the first and second records, respectively, and at the same time applying the next pointer part 8 of the first record and the previous pointer part 7 of the second record to the new record, you can easily change the record. Can be added.

However, in this kind of file read operation,
Normally, records are not necessarily physically stored in ascending order of records, so reading is performed sequentially starting from the first record and following the next pointer section 8.

[Problem to be solved by the invention]

As mentioned above, in the conventional file reading method, for example, when attempting to read the nth record from the beginning, the first record is read, the position of the second record is sought using the next pointer of this record, and the second record is read.
To repeat the operation of reading the th record,
This method has the disadvantage that it requires reading the record 0 times and seeking n times, which takes a large amount of time.

SUMMARY OF THE INVENTION An object of the present invention is to provide a file reading method that solves the above drawbacks and reduces the time required to read any record.

[Means to solve the problem]

The file reading method of the present invention reads an arbitrary record of a file using a file organization method that has pointers indicating the locations of records before and after an arbitrary record. Pointers indicating the records are stored in table format in ascending order of records.

〔Example〕

Embodiments of the present invention will be described based on the drawings.

FIG. 1 is a block diagram of a file reading method according to an embodiment of the present invention, and FIG. 2 is a diagram showing the structure of a file record.

As shown in FIG. 1, the file reading method of this embodiment is composed of a computer 1 consisting of an external storage device driver 3 and a memory 4, and an external storage device 2.
A table area 5 is secured above.

The record structure of the file shown in FIG. 2 is as described in the section of the prior art.

In FIG. 1, in the file reading method of this embodiment, first, when a command (such as a file open command) that declares the use of a file is issued to the external storage device driver 3 (hereinafter abbreviated as driver), the driver 3 secures a table area 5 on the memory 4 of the computer 1.

At the same time, the driver 3 reads the previous pointer part 7 and next pointer part 8 in FIG. Then, a pointer table indicating the location is created and stored in the table area 5 on the memory 4.

This pointer table is updated by the driver 3 every time records are added, deleted, rearranged, etc.

When a record reading command is issued to the driver 3, only when reading an arbitrary record, the pointer table in the table area 5 is first referred to, and the record at the location indicated by this pointer table is read.

As a result, when reading the n-th record from the beginning as in the above example, the reading process is completed within each seek time and record reading time, thereby shortening the reading time.

〔Effect of the invention〕

As explained above, according to the present invention, by storing pointers indicating the locations of all records in the memory of a computer in ascending order of the records in a table formation, the locations of records before and after an arbitrary record can be determined. The file organization method that has pointers that indicate this has the effect of greatly reducing the time it takes to read any record in the file.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a file reading method according to an embodiment of the present invention, and FIG. 2 is a diagram showing the structure of a file record. 1... Computer, 2... External storage device, 3...
- External storage device driver, 4...Memory, 5...Table area, 6...Data section, 7...Previous pointer section, 8...Next pointer section. Co-sinking 1-ta

Claims (1)

[Claims] In a file reading method that reads an arbitrary record of a file using a file organization method that has pointers that indicate the location of records before and after an arbitrary record, the location of all records is indicated on the memory of a computer. A file reading method characterized by storing pointers in table format in ascending order of records.