JP3297966B2 - Data access method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data access method, and more particularly to a data access method for accessing frequently used data stored on a secondary storage medium at a high speed.

[0002]

2. Description of the Related Art A conventional method for accessing a data file stored in a secondary storage medium or the like at high speed will be described below.

In the conventional method, when a data file on a secondary storage medium is accessed, data recorded in the data file on the secondary storage medium is stored in a buffer area prepared on a main storage device of the computer system. Is transferred, and access to the buffer area is speeded up. Usually, since the size of the buffer area is smaller than the size of the data file, only a part of the data of the data file can be transferred to the buffer area.
Therefore, when accessing data that has not been transferred to the buffer area, data on the secondary storage medium that has not been transferred to the buffer area is transferred by overwriting data that has already been transferred to the buffer area. . Hereinafter, a conventional method for improving the transfer efficiency of data from the secondary storage medium to the buffer area will be specifically described with reference to the drawings.

FIG. 8 is a flowchart showing the operation of the conventional method. The figure shows “ODP (On-Demand P
aging method), which is a method of reading data on a secondary storage medium via a buffer area on a main storage device.

(Step 100) A data read request from a user is accepted.

(Step 101) It is checked whether or not the data requested to be read exists in the buffer area.
Move to.

(Step 102) Step 101
If the data does not exist in the buffer area, one page of data, which is a data transfer unit predetermined by the system, is read from the secondary storage medium based on the read request.

(Step 103) It is checked whether or not an empty area exists in the buffer area. If an empty area exists in the buffer area, the process proceeds to step 105.

(Step 104) Step 103 above
If there is no free area in the buffer area, the data for one page read in step 102 is transferred so as to overwrite the data in the buffer area with a small number of read requests, and the process proceeds to step 106. .

(Step 105) Step 103 above
If there is an empty area in the buffer area, the data for one page read in step 102 is transferred to the empty area in the buffer area.

(Step 106) The above step 101
When the data requested to be read exists in the buffer area, and after the processing of steps 105 and 106, the data based on the read request is read from the buffer area and returned to the user.

FIG. 9 is a diagram illustrating a conventional method.
A specific example of the above method will be described with reference to FIG. In the description, it is assumed that the initial state of the buffer area is empty and no data is transferred. In addition, the user can see FIG.
"DATA1" and "DATA1" on the secondary storage medium
It is assumed that access is made sequentially to "3", and further access to any data on the secondary storage medium is continued thereafter. Then, when the buffer area becomes full, that is, when there is no more free area in the buffer area, access is made to "DATA5" which does not exist in the buffer area. This data will be described as “DATA21”.

A request for reading "DATA1" of a file on the secondary storage medium is received from the user (step 10).
0), since “DATA1” does not exist in the buffer area (step 101, NO), “DATA2” and “D” including “DATA1” from the file on the secondary storage medium are included.
The data of one page, which is a transfer unit predetermined by the system composed of "ATA3" and "DATA4", is read (step 102).

Since there is an empty area in the buffer area (step 103, YES), the read "DATA"
1 "," DATA2 "," DATA3 "," DATA
The data of one page consisting of "4" is transferred to the buffer area (step 105), "DATA1" is read from the buffer area and returned to the user (step 106).

In the following description, it is assumed that the buffer area is full because the user has continued to access data on the secondary storage medium.

Next, when a request to read "DATA3" of the file on the secondary storage medium is received from the user (step 100), "DATA3" exists in the buffer area (step 101, YES). Then, "DATA3" is read from the buffer area and returned to the user (step 106).

When a request to read "DATA5" of a file on the secondary storage medium is received from the user (step 10).
0), since “DATA5” does not exist in the buffer area (NO in step 101), “DATA6”, “DAT” including “DATA5” from the file on the secondary storage medium is included.
One page of data consisting of "A7" and "DATA8" is read (step 102).

Since there is no free area in the buffer area (step 103, NO), the data read out to the area starting with "DATA 21" which has the least read request among the data existing in the buffer area, ”,“ D
One page of data consisting of "ATA6", "DATA7", and "DATA8" is overwritten (step 104), and "DATA5" is read from the buffer area and returned to the user (step 106).

In the above-mentioned "ODP method", the unit of data transfer to the buffer area is performed by one page.
There are other ways to make this transfer unit a larger unit.
Further, as a method of determining an area in which data is overwritten when there is no free area in the buffer area, there is a method based on an access frequency, an elapsed time since last access, and the like.

[0020]

However, the above-mentioned conventional method has the following two problems.

The first problem is that data is transferred from the secondary storage medium to the buffer area in a transfer unit determined in advance by the system, so that even if the data has been transferred to the buffer area, a read request has never been made. There is a case where the data is overwritten by other data without occurrence, which may hinder the speeding up of the data access. To alleviate this problem, it is conceivable to design the data arrangement of the data file on the secondary storage medium in consideration of the data transfer unit and the frequency of read requests to the data in advance, but this is easy to realize. is not.

The second problem is that high-speed access can be realized when the data requested to be read has already been transferred to the buffer area, but when the data requested to be read has not been transferred to the buffer area. In this method, it is necessary to transfer data from the secondary storage medium to the buffer area, and then read and return the data from the buffer area.

The present invention has been made in view of the above points, and has as its object to provide an efficient data access method capable of preventing transfer of unaccessed data to a buffer area before it occurs.

It is another object of the present invention to provide a data access method capable of designating attribute information and collectively transferring data to be accessed on a secondary storage medium to a buffer area.

It is another object of the present invention to provide a data access method in which frequently accessed data is always stored in a buffer area based on attribute information set by a user and the number of accesses to a secondary storage medium can be reduced. With the goal.

It is another object of the present invention to provide a data access method capable of quickly determining whether to access a secondary storage medium or a buffer area when accessing data.

It is still another object of the present invention to provide a data access method capable of starting the data access after reproducing the same buffer area condition as at the end of the previous data access before starting the data access. .

[0028]

FIG. 1 is a diagram illustrating the principle of the present invention.

The present invention is directed to a file unit on a secondary storage medium.
In addition, the individual data areas that make up the file
Information indicating whether or not data has been transferred to the buffer area
Information (step 1), when the file is closed
The control information is used as a component of the file in the secondary storage medium.
Recorded on the body (step 2), when the file is opened
Then, the control information is read (step 3), and the previous file is read.
Data area that was transferred to the buffer area when the file was closed.
The area is transferred to the buffer area (step 4).

[0030]

[0031]

[0032]

[0033]

According to the present invention, the data area is transferred to the buffer.
Record the situation on the secondary storage medium as it is
Reproduces the same situation as the previous time when opening the file
It is possible to do.

[0034]

[0035]

[0036]

[0037]

[0038]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 2 shows a system configuration diagram for implementing the data access method according to one embodiment of the present invention. The system shown in FIG. 1 includes a computer 100, a hard disk 200, a display 300, and a keyboard 400.

The computer 100 includes a keyboard 100
Reads the data stored in the hard disk 200 based on the instruction of
Display to 0.

The memory 110 is a main storage device of the computer 100.

The buffer area 111 is a storage area secured in the memory 110, and has respective areas for storing data, attribute information, and control information. The attribute information and the control information will be described in detail in the following description of the hard disk 200.

The display 300 is connected to the computer 10
0 is a display device for displaying various information output by the user.

The keyboard 400 is connected to the computer 100
Is an input device for giving various instructions to the user.

The hard disk 200 is connected to the computer 1
00 is a secondary storage medium for storing various data files 210 usable. Below, the hard disk 200
An example of the data file 210 will be described with reference to the drawings. FIG. 3 is a diagram illustrating an example of a data file according to an embodiment of the present invention. The example shown in the figure is a data file 210 in which data “DATA1”, “DATA2”,... Are stored, attribute information corresponding to each data of the data file 210, and each data of the data file 210. An example in which corresponding control information is stored in the hard disk 200 is shown.

Each data indicates an access unit of the data to the hard disk 200, and the user can specify and access the data like "DATA1".

The attribute information is assigned to each data, and represents a group when the data is transferred to a buffer area in the memory 110. In the example shown in the figure, “DATA1”, “DATA2”,.
The same attribute information “10” is given to “5”, which indicates that they are defined as the same group. In this case, when the data “DATA1” is accessed, “DATA1”, “DATA2”,.
5 "is transferred to the buffer area 111 collectively. That is, data to which the same attribute information is assigned is a transfer unit to the buffer area 111. This transfer unit is different from a transfer unit such as one page previously determined by the system, and is not limited in size, and can be freely assigned by the user. The attribute information also indicates the order of erasure after the data is transferred to the buffer area 111. For example, if the data of the attribute information “10” and “20” has already been Does not exist, when other data to which attribute information “30” is added is transferred, the attribute information of the smallest value is newly added to the buffer area 111 in order from the data to which “10” is added. This means that the data will be overwritten and erased. In other words, by assigning attribute information having a large value to data with a high access frequency, even if there is no longer any free space in the buffer area 111, data with a low access frequency is overwritten and deleted in order. , Can be left in the buffer area. The user can perform data grouping according to data access frequency, access time, and the like, and assign attribute information based on the grouping result. In the example of FIG. 3, five data are set as a transfer unit.

The control information is information which is given for each data and indicates whether or not the data is transferred to the buffer area 111. In the example of FIG. 6, "0" is added to the control information. Indicates that the data is not transferred to the buffer area 111, and that the data to which “1” is assigned is transferred to the buffer area 111. The control information is not set by the user, but is information added when data is transferred to the buffer area 111 and when data is overwritten by the transfer. By storing this control information, prior to the start of access to the data file 210 on the hard disk 200, data in which the control information is 1 based on the control information, that is, the buffer area at the time of the previous data access is stored in the buffer area. The data access can be started after transferring the transferred data to the buffer area in advance.

The operation of the present invention will be described below with reference to the drawings. FIG. 4 shows a flowchart of a data access method according to one embodiment of the present invention.

[Preliminary Preparation for Data Access] (Step 10) The user preliminarily accesses the data of the data file 210 to be accessed in the hard disk 200 connected to the computer 100, for example, the access frequency and the access time. Attribute information according to is provided. [Access to Prepared Data] (Step 11) Hard Disk 200 by User
Based on the opening of the data file 210 in the buffer area 1, the attribute information and the control information of the data file 210 are stored in the buffer area 1.
11 and the data in the data file 210 is transferred to the buffer area 111 based on the control information.

(Step 12) The user specifies and accesses desired data in the data file 210.

(Step 13) It is checked whether or not the data specified in step 12 exists in the buffer area 111, and if the specified data exists in the buffer area 111, the process proceeds to step 19.

(Step 14) The attribute information of the data specified in step 12 is read from the buffer area 111.

(Step 15) It is checked whether or not there is a free area in the data area of the buffer area 111, and if there is a free area, the process proceeds to step 17.

(Step 16) The attribute information in the buffer area 111 is searched, and the data area storing the data having the smallest value of the attribute information is determined as the area for overwriting.

(Step 17) In step 15 described above,
When there is an empty area in the data area of the buffer area 111, and after the step 16, the hard disk 200
The data having the same attribute information as the attribute information of the data read in step 14 is transferred from the data file 210 in the buffer area 111 in a lump.

(Step 18) Hard Disk 200
Is set to 1 in the control information in the buffer area corresponding to the data transferred from the buffer area 111 to the buffer area 111, and 0 is set to the control information in the buffer area corresponding to the data overwritten and erased from the buffer area 111.

(Step 19) In step 13 described above,
The data specified in step 12 is the buffer area 11
1 and subsequent to step 18, the data designated in step 12 is read from the buffer area 111 and displayed on the display 300.

(Step 20) It is checked whether or not the user terminates the data access to the data file 210 in the hard disk 200. If the user repeatedly accesses the data without terminating the data access, the process proceeds to step 12. .

(Step 21) In step 20 described above,
When the user enters the data file 21 in the hard disk 200
When all data access to 0 is completed, the control information stored in the buffer area 111 is written to the control information area of the corresponding data file 210 in the hard disk 200, and the data file 210 is closed.

Hereinafter, a specific example of the above embodiment will be described. In the explanation, the user sets the attribute information corresponding to the data file 210 in the hard disk 200 as FIG.
It is assumed that the attribute information shown in FIG. In addition, the user can use “DATA1” → “DATA2” → “DATA
It is assumed that data is accessed in the order of “6”, and a free area exists in the buffer area 111 during this time.

The user, for each data of the data file 210 to be accessed in the hard disk 200 connected to the computer 100, attribute information (FIG. 3: attribute information) according to the access frequency, the access time, and the like.
(Step 10).

When the user issues a command to open the data file 210 in the hard disk 200, the attribute information and control information (FIG. 3) of the data file 210 are transferred to the buffer area 111 (step 11).

When the user specifies and accesses the data “DATA1” in the data file 210 (step 12), it is checked whether or not the specified data exists in the buffer area 111. Does not exist in the buffer area 111 (step 13, NO),
1 is retrieved and the designated data, the attribute information of "DATA1", and "10" are read (step 14).

Next, when it is checked whether or not there is a free area in the data area of the buffer area 111, there is a free area (step 15, YES).
, “DATA 1”, “DATA 2”,..., “DATA 1” having the attribute information “DATA 1” and the same attribute information “10” read from the data file 210 in the above step 14.
5 ”is read out at a time, and the buffer area 111 is read out.
(Step 17).

From the hard disk 200 to the buffer area 11
, "DATA1", "DATA2", ..., "DATA
The control information in the buffer area corresponding to "5" is set to "1" (FIG. 5) (step 18).

The data designated by the user in step 12, “DATA1”, is read from the buffer area 111 and displayed on the display 300.
(Step 19).

Since the user repeatedly accesses the data (step 20, NO), when the data “DATA 2” in the data file 210 is designated (step 12), the designated data exists in the buffer area 111. When it is checked whether or not to execute, the specified data is present in the buffer area 111 (step 13, YES), so the specified data, "DATA2", is read from the buffer area 111 and displayed on the display 300 (step 19). .

Since the user repeatedly accesses the data (step 20, NO), when the user specifies the data “DATA6” in the data file 210 and accesses the data (step 12), the specified data exists in the buffer area 111. It is checked whether or not to execute, but the specified data does not exist in the buffer area 111 (step 13, NO), so the buffer area 11
1 is retrieved and the designated data, the attribute information of "DATA6", and "20" are read (step 14).

Next, when it is checked whether or not there is a free area in the data area of the buffer area 111, there is a free area (step 15, YES).
, “DATA6”, “DATA7”,..., “DATA6” having the attribute data “DATA6” and the same attribute information “20” read from the data file 210 in the above step 14
10 ”is read out at a time, and the buffer area 111 is read.
(Step 17).

From the hard disk 200 to the buffer area 11
1, "DATA6", "DATA7", ..., "DATA
The control information in the buffer area corresponding to "10" is set to "1" (FIG. 6) (step 18).

The data designated by the user in step 12, “DATA6”, is read from the buffer area 111 and displayed on the display 300.
(Step 19).

Since the user terminates the data access (step 20, YES), the control information (FIG. 6) stored in the buffer area 111 is transferred to the corresponding hard disk 2
The data file 210 is written in the control information area of the data file 210, and the data file 210 is closed (step 21).

According to the above embodiment, the transfer of the data in the secondary storage medium (hard disk 200), which has been set in advance by the system and could not be set by the user, to the buffer area 111 conventionally. Control can be set by the user, and high-value attribute information is used for frequently accessed data or data that is accessed immediately, and data with low access frequency or data that is not accessed for the time being. On the other hand, by setting a small value, it is possible to frequently store data that is frequently accessed and that is desired to be used immediately in the buffer area 111. Accordingly, it is possible to prevent frequently accessed data from being accessed and acquired from the secondary storage device, thereby realizing high-speed data access.

Next, following the above embodiment, a specific example in which the user accesses the data of the data file 210 in the database 200 will be described. It should be noted that since the processing is a continuation of the above embodiment, the data file 210
It is assumed that the same contents as the control information of the buffer area 111 of FIG. 6 have been written in the control information of FIG. It is assumed that the buffer area 111 runs out of free space when 10 data are stored. It is assumed that the user accesses data in the order of “DATA1” → “DATA21”.

When the user issues a command to open the data file 210 in the hard disk 200, the attribute information (FIG. 3: attribute information) and the control information (FIG. 6: control information) of the data file 210 are stored in a buffer area. 111 and the data file 210 based on the control information.
The data inside is transferred to the buffer area 111 (FIG. 6) (step 11).

When the user specifies and accesses the data “DATA1” in the data file 210 (step 12), the user checks whether or not the specified data exists in the buffer area 111. Since the data exists in the buffer area 111 (step 13, YES), the designated data, "DATA1", is read from the buffer area 111 and displayed on the display 300 (step 19).

Since the user repeatedly accesses the data (step 20, NO), when the user specifies the data “DATA 21” in the data file 210 (step 12), the specified data exists in the buffer area 111. It is checked whether or not to execute, but the specified data does not exist in the buffer area 111 (step 13, NO), so the buffer area 11
1 is retrieved and the designated data, attribute information of "DATA21", and "30" are read (step 14).

Next, it is checked whether or not there is a free area in the data area of the buffer area 111. Since there are no free areas since ten data are already stored (step 15, NO), , The attribute information of the smallest value, data to which “10” is assigned, “DATA1”, “DATA2”,.
5 is determined as an area for overwriting (step 16).

The data read from the data file 210 in the hard disk 200 in step 14, “DATA 21” attribute information, “DATA 21” having the same attribute information as “30”, “DATA 22”,. "DA
TA25 ”is read out at a time,
Is transferred to the overwriting area in the buffer area 111 determined in step (step 17).

From the hard disk 200 to the buffer area 11
1, "DATA21", "DATA22", ..., "DA
The control information in the buffer area corresponding to “TA25” is “1”, and the data overwritten and deleted from the buffer area 111 are “DATA1”, “DATA2”,.
The control information in the buffer area corresponding to "5" is set to "0" (FIG. 7) (step 18).

The data designated by the user in step 12, “DATA 21”, is read from the buffer area 111 and displayed on the display 300.
(Step 19).

Since the user ends the data access (step 20, YES), the control information (FIG. 7) stored in the buffer area 111 is transferred to the corresponding hard disk 2
The data file 210 is written in the control information area of the data file 210, and the data file 210 is closed (step 21).

According to the above embodiment, the database 200
Since the control information at the time of the previous access is written in the middle data file 210, when the same data file 210 is used again, before the access to the data file, the state at the time of the previous close is changed. Since the same state of the buffer area 111 can be automatically reproduced, high-speed access is possible from the start of data access.

Next, an example will be described in which the user inputs desired attribute information at the time of starting data access and transfers data having the attribute information to the buffer area in advance. The flowchart of the data access method at that time is basically the same as that shown in FIG. However, step 1
In 2, the user can input desired attribute information in addition to specifying desired data. Also,
If the user inputs the attribute information in step 12, then the process proceeds to step 15, and in step 17, data having the same attribute information as the read data is collectively stored in the buffer area 111. Instead of transferring the data, the data having the same attribute information as the specified attribute information is transferred to the buffer area 111 collectively. Further, step 19 is skipped.

In the above embodiment, if the data already transferred to the buffer area 111 is not desired to be overwritten, the overwriting can be avoided by changing the value of the attribute information in the buffer area 111. For example, in the state of the buffer area 111 shown in FIG.
Assuming that there is no free space in the data, the next access to the data, "DATA21", the data, "DATA1", "DATA2", ..., "DATA
"5" is data, "DATA21", "DATA22", ..., "DA
TA25 ". This has already been specifically described in the above embodiment. However, if the user does not want to overwrite the data, “DATA1”, the data, “DATA1”, “DATA2” in the buffer area 111 before accessing the data, “DATA21”. , ..., "DATA
The attribute information of “5” can be changed from “10” to a large value such as “40”. As a result, when the data “DATA21” is accessed, the attribute information in the buffer area 111, the data “20”, “DATA6”, “DATA6”,.
10 "is determined as the overwriting area.

In the present embodiment, an example has been described in which the user directly specifies and accesses each data stored in the data file 210 of the hard disk 200. Is a computer 100
In some cases, the computer 100 automatically accesses the hard disk 200 based on some processing that is requested to the user, and the access to data is not limited to direct access by the user.

In this embodiment, the hard disk 20
0, the attribute information and the control information are stored together with the data in the data file 210.
It is also possible to have attribute information and control information as a separate file from the data file 210.
However, the present invention is not limited to this.

In this embodiment, an example is shown in which data obtained by data access is displayed on the display 300. However, the data obtained by access can be calculated or stored in another file. However, the present invention is not limited to this.

Further, in this embodiment, an example has been shown in which attribute information having a large value is assigned to data having a high access frequency or data which is accessed immediately. It is also possible to add attribute information of a small value to the data, and it does not limit how to determine the value of the attribute information, but can be set freely within the scope of the claims.

[0091]

As described above, according to the present invention, the file
The state at the time of closing the file is transferred to the secondary
By recording, it is closed when the file is opened
Because it is possible to reproduce the same situation as
High-speed data access from the beginning of access
Can be.

[0092]

[0093]

[0094]

[0095]

[0096]

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a system configuration diagram for implementing a data access method according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating an example of a data file according to an embodiment of the present invention.

FIG. 4 is a flowchart of a data access method according to an embodiment of the present invention.

FIG. 5 is a diagram (1) illustrating a progress of execution of an embodiment of the present invention.

FIG. 6 is a diagram (2) for explaining the execution progress of an embodiment of the present invention.

FIG. 7 is a diagram (3) illustrating a process of executing the embodiment of the present invention.

FIG. 8 is a flowchart showing the operation of the conventional method.

FIG. 9 is a diagram illustrating a conventional method.

[Explanation of symbols]

 Reference Signs List 100 computer 110 memory 111 buffer area 200 hard disk 210 data file 300 display 400 keyboard

Continuation of the front page (56) References JP-A-4-148225 (JP, A) JP-A-62-106553 (JP, A) JP-A-2-141840 (JP, A) JP-A-2-165353 (JP) JP-A-63-313252 (JP, A) JP-A-63-201845 (JP, A) JP-A-59-8071 (JP, A) JP-A-3-164840 (JP, A) 7-28677 (JP, A) JP-A-7-13844 (JP, A) JP-A-6-231022 (JP, A) JP-A-6-83746 (JP, A) (58) Fields investigated (Int. Cl. ^7, DB name) G06F 12/00 G06F 12/08 G06F 3/06

Claims (1)

(57) [Claims] (1)Files are stored in units of files on the secondary storage medium.
The individual data areas that make up the file are buffered in main memory.
Information indicating whether or not the data has been transferred to the
Manage, When the file is closed, the control information is stored in the file.
Recorded on a secondary storage medium as a component of the Reads the control information when opening the file
Is transferred to the buffer area when the file was last closed.
Transfer the data area to the buffer area.
Data access method to be used.