JPS61224049A - Access control system of indexed sequential file - Google Patents

Abstract

PURPOSE:To make the operation of indication to a former position unnecessary and to improve the processing efficiency by restoring the former sequential access call point to restart sequential access simultaneously with the end of an additional control when sequential access call is interrupted to perform the additional control. CONSTITUTION:A key value of a record in a file device 3 accessed by an access position control part 7 is set to a pointer 11 of an indexed sequential file access control part 2 of a processor 1. Contents of the pointer 11 are increased by +1 by a computing element 12 to read the continuous key value to a call control part 8 unless an instruction which designates a discontinuous key position is issued. When a command decoding part 6 detects an addition command, sequential access of the control part 7 is interrupted by an addition control part 9. The next access position of sequential access of the pointed 11 and its related information are saved in a work area 14 of a main memory 13, and a key value of an additional position is set to the pointer 11, and the saved key value is restored in the pointer 11 to restart access control when the addition processing is terminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] A control means is provided to automatically separate sequential access and random access to an indexed sequential file, thereby simplifying the operating procedure in mixed access.

[Industrial application field]

The present invention relates to a file management method in a data processing system, and particularly to an efficient access control method for indexed sequential files.

[Conventional technology]

Indexed sequential file (or multiple indexed file)
It consists of multi-level indexes and data records arranged in key order, and has the feature that both sequential access and random access are possible.

By the way, in general, when processing an indexed sequential file, a mixture of sequential access and random access is performed, such as sequentially accessing some records or accessing records at discontinuous key positions during sequential access. There are many cases. However, conventionally, in such cases, sequential access and random access have been performed as independent processes. Next, I will explain using a concrete example.

FIG. 4 shows a simple example of the file structure. It consists of an index file and a data file, and records with key values 1 to 11 are arranged. Note that FIGS. 2(a) and 2(b) show the state of the file before and after additional processing, which will be described later, respectively.

Here, using the file shown in Figure 4(a), for example, add a record with a key value of 8 between sequential access processing of records with key values 1, 2.3 and records with key value 4.5, etc. The control procedure according to the conventional method as an example of processing is shown in the flowchart of FIG.

First, in steps (2), (2), and (2), records with key values 1, 2.3 are sequentially accessed and read from the beginning of the file, and in step (2), the sequential access processing is temporarily terminated. Next, in step ■, add a record with key value 8, and
) In order to start sequential access again in step ■, the file state is set to the file state shown in ), random access is performed to position the record with key value 4 next to the original end position, and the order in which the record with key value 4 positioned in step ■ is read. The access is performed, and thereafter, the access is performed sequentially as shown in step (■).

In other words, when repeating sequential access - random access - sequential access in this way, an instruction is given to end the sequential access in the process of transitioning from sequential access to random access, and later, sequential access is started from the position where it ended earlier. When restarting, the user had to remember the position where it ended and instruct it to specify it as the first record position.

Also, unless there are special instructions, the 9th record.

Although it is called by sequential access, if there is no instruction to end the sequential access, it is impossible to call by random access or perform additional processing.

[Problem that the invention seeks to solve]

In the conventional access control method for indexed sequential files, as mentioned above, sequential access and random access are distinguished as separate access and control, and this separation is done by using sequential access termination instructions, additional instructions, and specific position Attachment was done according to instructions.

Therefore, in processes where random access frequently occurs during sequential access, there is a problem that operations are complicated, errors are likely to occur, and the burden on the user is heavy. [Means for solving the problem] The present invention solves the problems of the conventional method described above.
Identifies and separates the value specified as the key value that should be processed as the primary process for sequential access and random access, and when performing additional processing during sequential access, temporarily suspends sequential access so that it can be recovered. It is designed to perform access control.

FIG. 1 exemplarily shows the basic configuration of a data processing system based on two methods of the present invention. In the figure, 1 is a processing device, 2 is an index sequential file access control unit, 3 is a file device, 4 is an index sequential file, 5 is a display terminal device, and 10 is a processing program.

In the processing device 1, an index order file access processing section 2
The processing program 10 issues macro commands to the processing device 1 to control access to the index-ordered file 4 of the file device 3 in accordance with instructions given by the user from the display terminal device 5.

Access control is divided into data recall and additional functions.

In the case of data call control, the display terminal device 5
Based on the leading key value indicated by.

Generate sequential key values to be accessed in succession.

When the next key value is specially specified, the sequential access shifts to random access, and when an addition is instructed, the sequential access is temporarily interrupted and restarted when the instructed addition processing is completed.

In the case of sequential access, the previous key value is advanced by one, and in the case of random access, the pointer is set using the input key value.

When a sequential access call is interrupted to perform additional control, upon completion, the original interruption point of the sequential access call is restored and the sequential access is resumed.

[Effect]

The operation of the system of the present invention will be explained using a specific example shown in the flowchart of FIG. The flow in Figure 3 is as follows.

This corresponds to the flow of the conventional method shown in FIG. 4 in which the file shown in FIG. 4 is accessed.

In step ■, read the record with key value ■ at the beginning of the file.

In steps (2) and (2), since a read command for sequential access has been issued, it is determined that the access is sequential, and the records with key values 2 and 3 are sequentially read.

Add a record with key value 8 in steps ■ and ■ ′
However, at this time, the key value 4 following the previous key value 3 is saved, the sequential access is interrupted, and record addition control is performed.

In steps (2) and (2), the end of the additional control in step (2) is identified, the previously saved key value 4 is restored, and the record thereof is read.

In step (2), since a read instruction for sequential access has been issued, call control using sequential access is continued.

In this way, sequential access is interrupted when additional processing is automatically identified, and sequential access is automatically continued from the original position after performing the additional processing.

〔Example〕

FIG. 3 shows the configuration of a system according to an embodiment of the present invention.

In FIG. 3, 1 is a processing device, 2 is an index sequential file access control section, 3 is a file device, 4 is an index sequential file, 5 is a display terminal device, 6 is a command analysis section, 7
is an access position control unit, 8 is a call control unit, 9 is an additional control unit, 10 is a processing program, 11 is a pointer, 12
13 represents a main memory, and 14 represents a work area.

The command analysis unit 6 allows the user to use the display terminal device 5.
a call input from and issued by the processing program 10;
Identify additional commands, key values, data, etc. and activate the corresponding control unit, key value.

Transfer data etc.

When issuing a sequential read command without specifying an access position (key value), the access position control unit 7 sets the first key value of the index sequential file 4 to be accessed in the pointer 11. ), by the call control unit 8.

Read the record with the first key value.

From now on, the access position control unit 7 uses the arithmetic unit 12 to increase the value of the pointer 11 by +L for each access, unless a random read command specifying a discontinuous key position is issued.
L. Causes the call control unit 8 to read consecutive key value records. In other words, sequential access is performed. However, the access position control unit 7 uses the pointer 11 as the ninth key value.
If a random read instruction has been issued that specifies a discontinuous key value different from the value of Perform sequential access while increasing the pointer value by 1.

Further, when the command analysis unit 6 detects a data addition command, the additional control unit 9 is activated. For example, when the additional control unit 9 is activated, the additional control unit 9 controls the access position control. interrupting the sequential access control of section 7;
2. Save the value of the pointer 11, that is, the key value indicating the next access position in the case of sequential access, and related control information to the work area 14, and instead set the key value specified as the additional position to the pointer 11, Execute predetermined additional processing.

When the addition process is finished, the saved key value is restored to the pointer 11, and the access position control unit 7 is caused to resume sequential access control.

〔Effect of the invention〕

As described above, in access control of indexed sequential files, the present invention allows random access to be performed simply by specifying a discontinuous key value as the next key value during sequential access control, and does not require additional requests. If the sequential access control is interrupted, the addition is performed, and the sequential access operation is automatically restarted from the original interrupted position when the sequential access control is terminated. There is no need to specify the original location to resume access.

User operations are simplified and processing efficiency is improved.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the basic configuration of the zero invention, Fig. 2 is a flow diagram showing the control procedure of the method of the present invention, Fig. 3 is a block diagram of an embodiment of the system of the method of the present invention, and Fig. 4 is a diagram of the system according to the present invention. An explanatory diagram showing an example of the configuration, FIG. 5 is a flow diagram showing the control procedure of the conventional system. In FIG. 1 is a processing device. 2 is an index sequential file access control unit. 3 is a file device. 4 is an index sequential file. 5 is a display terminal device. 10 indicates a processing program. Patent applicant Fumihiro Hase (2 others), Patent attorney representing Yusank Electronics Industry Co., Ltd. Bottle 4 multi-system bqdl relation (4J-~1 7 eye 1 tighten 1 #R liquid retarder 64

Claims (1)

[Scope of Claims] In a data processing system having an indexed sequential file and an indexed sequential file access control unit, the indexed sequential file access control unit controls the key value of the record to be accessed in the indexed sequential file. A pointer to be set, a means for setting a sequential key value to the above pointer for each access during sequential access call processing, and a key value that is different from the sequential key value due to sequential access as the key value of the next record to be accessed. If specified, means for setting the specified key value in a pointer, and if additional processing is specified, interrupting sequential access control and executing the specified additional processing, An access control method for an indexed sequential file, comprising means for restarting the interrupted sequential access control from the interrupted key value when the processing is completed.