JPH05181726A - File access system - Google Patents

Abstract

PURPOSE:To attain file access without stopping an updating program in case of accessing a file being updated by a program in the status of a certain point of time at the time of executing the file access based upon continuous operation. CONSTITUTION:Since a static information part 123 for storing a static key specified from a program 100 at a certain point of time is included in a record 122 and a file access part 110 capable of retrieving or updating the record 122 corresponding to the specified static key is included in this file access system, so that a file in the status of a certain point of time specified by the program 100 can be accessed without stopping the updating program 100.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to file access, and more particularly to file access by continuous operation.

[0002]

2. Description of the Related Art A conventional file access method is a record a stored in a data section 230 as shown in FIG.
From the record address 220 that manages the address of (240) and the record b (250) and the record access key 210 that manages the access key for accessing the record a (240) and the record b (250) from the program. The file access unit 260 uses the index unit 200 to access the record requested by the program.

Next, the operation will be described.

From the program, the record access key K ₁
Is specified, the file access unit 260 searches the record access key 210 of the index unit 200 for a record access key having the same value, and the record a (240)
Will be returned to the program.

When the program requests update of the record a (240), the file access unit 260 changes the contents of the record a (240) with the designated image.

As described above, the content of the record a (240) is changed every time there is an update request from the program.

[0007]

Conventionally, in this type of file access method, when accessing a file in a state at a certain time point, it is necessary to stop all programs updating the file at that time point. Then there was a problem that the file could not be used.

An object of the present invention is a file which, when accessing a file in a state at a certain point in file access by continuous operation, makes it possible to access a file in a certain quiescent state without stopping the program being updated. To provide an access method.

[0009]

According to the file access method of the present invention, a file access means for accessing a file at a time point (hereinafter referred to as a quiescent point) set by a program, and an access key required for accessing a record. It is provided with index information in which information is stored, stationary management information for managing the record of the stationary point, and data for storing the record of the stationary point.

[0010]

The present invention will be described below with reference to the drawings.

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

According to the file access method of the present invention, a file 120 including an index section 121 and a record 122, and a record 12 including a static information section 123 and a data section 124.
2, a file access unit 110 and a program 100.

FIG. 3 is a diagram showing the structure of the record 122.

The stationary information section 123 includes a stationary key 130 and an N key.
It comprises an EXT address 131 and a delete flag 132. The static key 130 stores key information for determining a static point (static keys are set in ascending order). NEXT
The address 131 indicates the address of the record that stores the data updated for each stationary point, and the data updated at the final stationary point has a value indicating the final point at that time. The deletion flag 132 has a value indicating whether or not the record is deleted by the program at the stationary point.

The structure of the index unit 121 is similar to that of the index unit 20 shown in FIG.
Same as 0.

When the access key and the static key of the record to be referred to are specified by the program 100, the file access unit 110 searches the same record access key 210 from the index unit 121 to obtain the record address 220 to be accessed, Read the corresponding record. If the static key 130 and the static key designated by the program 100 (hereinafter referred to as the designated static key) are the same, the data of the record is passed to the program 100. If the static key 130 is smaller than the designated static key, the record pointed to by the NEXT address 131 is read. If the still key 130 of the read record is smaller than the designated still key, the data of the previously read record is passed to the program 100.

When the NEXT address 131 is reached and the final record is reached, a response indicating that there is no corresponding record is returned to the program 100.

However, the deletion flag 132 of the corresponding record
Even if the message “Delete” is entered, a response indicating that there is no corresponding record is returned to the program 100.

When there is an update request from the program 100,
The file access unit 110 only changes the data if the static key 130 of the corresponding record and the designated static key are the same.

If the designated static key is larger than the static key 130, the address of the record to be newly added is stored in the NEXT address 131, and the data of the record to be added is stored as the data designated by the program 100.

Next, the operation of the file access method of this embodiment having the above configuration will be described.

In FIG. 4, record # 1 and record # 2 are stored in the file, and the respective record access keys 210 are K ₁ and K ₂ . The stationary key 130 is 1.

In such a state of the file 120, when the quiesce key 130 is designated by the program 100 by 2 at a certain quiesce point and an update request is made for the record # 1 with the data # 3, the file access unit 110 causes the record access. The key 210 is searched for K ₁ , the record address of the record # 1 is obtained, and the record # 1 is read. The static key 130 of record # 1 is compared with the designated static key, and the static key 13
Since 0 is small, the NEXT address 131 is referenced.
Since the value indicating the last record is stored, NE
The address of the record # 3 to be newly added is set in the XT address 131. Data # 3 is set in the data of the record # 3 to be added, a value indicating the final record is set in the NEXT address 131, a value indicating that the deletion flag 132 exists is stored in the file 120.

At the quiesce point, when the quiesce key 130 is designated by 3 from the program 100 and an update request is made for record # 2 with data # 4, the file access unit 110 retrieves K ₂ from the record access key 210, Record # 2
Get the record address of and read record # 2. Compare the static key 130 of record # 2 with the designated static key,
Since the static key 130 is small, the NEXT address 131
Refer to. Since the value indicating the last record is stored, the address of the record # 4 to be newly added is set in the NEXT address 131. Record to add #
The data # 4 is set to the data of No. 4, the value indicating the final record is set to the NEXT address 131, the value indicating that the deletion flag 132 exists is entered, and the file 12
Store in 0. Such a state is shown in FIG.

In the state shown in FIG. 5, when there is a request from the program 100 for a record in which the quiescent key 130 has 2 and the record access key 210 has K ₂ , the file access unit 110 first searches for record # 2. .. Since the value of the static key 130 of the record # 2 is smaller than the value of the designated static key, the NEXT address 131 is referred to, the record address of the record # 4 is obtained, and the record # 4 is read. Since the value of the static key of the record # 4 is larger than the value of the designated static key, the data of the record # 2 read last time is passed to the program 100.

[0026]

As described above, according to the present invention, since the static key designated by the program at the static point is provided for each record, the file at the static point is accessed without stopping the program. Has the result that it was possible to do.

[Brief description of drawings]

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

FIG. 2 is a diagram showing an example of conventional file access.

FIG. 3 is a configuration diagram of a record 122 shown in FIG.

FIG. 4 is a diagram for explaining the operation of the file access method according to the embodiment.

FIG. 5 is a diagram for explaining an operation in another state of the file access method according to the embodiment.

[Explanation of symbols]

 100 program 110 file access part 120 file 121 index part 122 record 123 static information part 124 data part 130 static key 131 NEXT address 132 delete flag 200 index part 210 record access key 220 record address 230 data part 240 record a 250 record b 260 file Access section

Claims (1)

[Claims] 1. A file access means for accessing a file at a time set by a program (hereinafter referred to as a quiesce point), index information in which access key information necessary for accessing a record is stored, and a quiesce point. A file access method characterized by comprising stationary management information for managing the records of the above, and data for storing the records of the stationary points.