JPH0212346A - Data assurance system - Google Patents

Abstract

PURPOSE:To improve the data assurance factor without deteriorating the file access speed by writing the dummy records in pairs after each record in a writing state, overwriting the dummy records in the next record writing state, and recognizing the end of a record when a dummy record is detected in a reading state. CONSTITUTION:A writing part 11 writes a dummy record after each record to show the end of this record and then overwrites said dummy record when the next record is written. A reading part 12 recognizes the end of a record when a dummy record is detected instead of the EOD (end of data) in a reading state. Thus it is not required to replace the EOD of an auxiliary memory 20 each time. As a result, the latest data can be assured at all times without deteriorating the file access speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is applied to a data guarantee system for sequential files in computers. In particular, it relates to a sequential file management system with a high data guarantee rate.

〔overview〕

In the data guarantee method of the present invention, a dummy record indicating the end of the 17 codes is written next to each record as a bare record at the time of writing, this dummy record is overwritten when writing the next record, and this dummy record is written at the time of reading. By recognizing this as the end of a record when a record is detected, it is possible to always guarantee the latest data without slowing down file access speed.

[Conventional technology]

FIG. 5 is a diagram showing the operation of a conventional data guarantee device.

Conventionally, the data guarantee method is E OD (end of d
data) was updated in memory, and the file label was updated when the file was closed to guarantee data.

Here, the record storage procedure of a conventional sequential file will be explained with reference to FIG.

This example shows the operation when storing three records.

First, record 1 is written. In FIG. 5(a), record 1 is stored from the position of the sequential file 25 indicated by the E OD 23 in the auxiliary storage device 20, and at the same time, the E OD 31 on the memory 30 is updated. However, at this time, the EOD23 in the auxiliary storage device 20 is not updated.

Next, record 2 is written. In Fig. et al.),
Record 2 is stored from the position of the sequential file 25 indicated by the updated E OD 31 on the memory 30 in FIG. 5(a), and at the same time, the E OD 31 on the memory 30 is updated.

However, at this time, the EOD 23 in the auxiliary storage device 20
is not updated.

Next, record 3 is written. In FIG. 5(C), record 3 is stored in the position of the sequential file 25 indicated by EOD31 on the memory 30 that has been updated in FIG.
At the same time, EOD31 on memory 30 is updated.

However, the EOD 23 in the EOD in the auxiliary storage device 20 is not updated.

Next, close the file. In FIG. 5(d), the EOD 31 on the memory 30 that has been updated in FIG. 5(C)
The contents of are stored in EOD23 in the auxiliary storage device 20,
The file label 24 is updated.

Therefore, records 1 to 3 are guaranteed for the first time in the operation shown in FIG. 5(6).

[Problem that the invention seeks to solve]

However, in such a conventional data guarantee method, since EOD31 on the memory 30 is updated, if a failure occurs midway, EOD23 on the sequential file 25 will not be updated. There was a drawback that the data became invalid.

The present invention solves the above-mentioned drawbacks, and aims to provide a data guarantee method that can always guarantee the latest data without reducing file access speed.

[Means for solving problems]

In the data guarantee method, the present invention includes means for writing a dummy record next to each record to indicate the end of that record, and overwriting this dummy record when writing the next record; The department includes
The present invention is characterized in that it includes means for recognizing the end of the record when the dummy record is detected.

[Effect]

The writing section writes a dummy record next to each record indicating the end of that record, and overwrites this dummy record when writing the next record. When the reading unit detects this dummy record instead of the EOD during successive reading, it recognizes that the record has ended. Due to the above operation, it is not necessary to update the EOD of the auxiliary storage device every time.
You can always guarantee the latest data without reducing file access speed.

〔Example〕

Embodiments of the present invention will be described with reference to the drawings. 1st
The figure is a block diagram of a data guarantee device according to an embodiment of the present invention. In FIG. 1, the data guarantee device 10 includes a writing unit 11 that sequentially writes a plurality of records to a sequential file 25 as a file, and a read unit 11 that sequentially reads a plurality of records written to the sequential file 25. 12.

The auxiliary storage device 20 is a BOE (beginning
of extent) 21 and E OE (endo
The file label 24 includes a file label 24 containing a file (extent) 22, and a sequential file 25.

Here, the feature of the present invention is that the writing unit 11 writes a dummy record next to each record indicating the end of that record, and includes means for overwriting this dummy record when writing the next record. Contains and reads part 1
2 is to include means for recognizing the end of a record when the dummy record is detected.

The operation of the data guarantee device having such a configuration will be explained. FIG. 2 is a diagram showing the operation of the data guarantee device of the present invention. FIG. 3 is a flowchart showing the operation of the writing section of the data guarantee device of the present invention. FIG. 4 is a flowchart showing the operation of the reading section of the data guarantee device of the present invention.

The operation of the writing section will be explained with reference to FIGS. 1 to 3. For example, when writing records 1 to 3,
First, record 1 is written.

In FIG. 2(a), record 1 and data end record are stored bare from the position of the sequential file 25 indicated by BOE21 of the file label 24 in the auxiliary storage device 20 (Sl). Record 1 is guaranteed by storing the data end record. Since all records are not completed (S2), record 2 is written. 2), record 2 and the data end record are stored bare from the position of the data end record stored in FIG. 2(a) (S3). Records 1 and 2 are guaranteed by storing the data end record.

Since all records are not finished (S2), record 3
Write. In Fig. 2ffl(C), Fig. 2(b)
) Record 3 from the position of the data end record stored in
and the data end record is stored bare (S3).

Record 1, record 2, and record 3 are guaranteed by storing the data end record.

Since all records have been completed (S2), the operation is ended.

The operation of the reading section will be explained with reference to FIGS. 1 and 4. First, record 1 is output one after another.

B OE2 of file label 24 in auxiliary storage device 20
A record is read from the position of the sequential file 25 indicated by 1 (Sit). If this record is not the data end record (S12), the next record is read. If the read record is the data end record (S12
), the operation ends.

〔Effect of the invention〕

As explained above, the present invention has the excellent effect of always guaranteeing the latest data without reducing file access speed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a data guarantee device according to an embodiment of the present invention. FIG. 2 is a diagram showing the operation of the data guarantee device of the present invention. FIG. 3 is a flowchart showing the operation of the writing section of the data guarantee device of the present invention. FIG. 4 is a flowchart showing the operation of the reading section of the data guarantee device of the present invention. FIG. 5 is a diagram showing the operation of a conventional data guarantee device. 10... Data guarantee device, 11... Writing section, 12.
...Reading unit, 20...Auxiliary storage device, 21...BO
E, 22...EOE, 23.31...EOD, 24
...File label, 25...Order 4it fine novel 30 =...Memory.

Claims (1)

[Claims] 1. In a data guarantee method comprising a writing section that sequentially writes a plurality of records to a file, and a reading section that sequentially reads the plurality of records written to the file, The reading section includes means for writing a dummy record indicating the end of the record next to each record, and overwriting this dummy record when writing the next record; A data guarantee method characterized by comprising means for recognizing this as the end of a record.