JP2007004326A - Data access method and program therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain high speed access in processing for performing access to data in a data file of a large size stored in a storage device, especially, repeated access to a data group in an arbitrary portion of extent. <P>SOLUTION: A data file in a storage device is successively accessed from the top to designated data, and the association of the ID of record groups for the predetermined number of records and a leading address in the storage device is registered in an index memory, and the record group to which the designated data are belonging is transferred to a work memory, and data access to the work memory is performed. When any designated data are not present in the work memory, the record group at the leading address already registered in the index memory is transferred to the work memory, and the data file is successively accessed from the leading address already registered in the index memory to the designated data, and the record group to which the designated data are belonging is transferred to the work memory, and data access to the work memory is performed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a data access method and a program for accessing data in a large-sized data file stored in a predetermined storage means at high speed.

In general, large data files (volumes) are stored in storage means that have a low bit rate but a relatively slow access speed, as represented by disk-type storage devices such as hard disk devices and magneto-optical disk devices. Often used. Hereinafter, such a storage means is referred to as a low speed memory. On the other hand, the RAM and the like have a high bit rate while having a high access speed. Hereinafter, such a storage means is referred to as a high-speed memory.
When accessing the data to be accessed (hereinafter referred to as specified data) for a large data file stored in low-speed memory, for example, identification information of the specified data in the data file (eg, record number) , Relative position information in the data file, hereinafter referred to as designated data ID) is designated first. Usually, from the data located at the top address (address (pointer) indicating the position of the top data) of the data file in the low-speed memory obtained through the file system included in the OS (operation system) or the like until the designated data is reached. That is, subsequent data is sequentially accessed until the data corresponding to the designated data ID is reached. That is, every time data is accessed, the address of the next (subsequent) data is obtained through the file system, and the designated data is accessed by sequentially tracing the address. Hereinafter, such data access is referred to as sequential access.

However, when frequent data access is performed, if the sequential access is performed every time specified data is accessed, there is a problem that it takes a long time to access the data.
Of course, if the data file is transferred to the high-speed memory in advance and then the data is accessed in the high-speed memory, high-speed access is possible. On the other hand, not only high memory cost is required, but also the performance of the entire system (computer) is improved. The problem of worsening also arises.
On the other hand, Patent Document 1 discloses that, among master files (an example of a data file), fixed item data with little update processing is stored as an index sequential file in a high-speed memory, and variable item data with many update processing is stored in a large-capacity A master file maintenance method is shown in which a fixed item and a variable item can be simultaneously accessed by constructing each as a directly-organized file in a disk device, thereby reducing waiting time.
In Patent Document 2, the entire area of the measurement data of the object to be measured is divided into a plurality of small areas in advance, and the start point / end point of each of the small areas and the measurement order are stored. A data storage method for storing measurement data in a memory and transferring it to an external memory is shown.
JP-A-4-304536 JP-A-10-2762

However, in the technique disclosed in Patent Document 1, since the access to the magnetic disk having a low access speed is performed every time for the frequently accessed data (the data of the variable item), the speed of the entire access process is slow. There was a point.
In addition, when the technique disclosed in Patent Document 2 is applied to access to large data stored in a low-speed memory, all large data is stored in order to store in advance information on the start and end points of all small areas. However, there is a problem that at least one prior access is required, and the start of processing is delayed as the data size increases.
Here, in accessing a large data file, it is often the case that after accessing a certain data, the data and a data group existing in a relatively close range before and after that data are repeatedly accessed. There is a process to be performed. One example is data graphing processing in so-called spreadsheet software. In such a process in which a partial data group is repeatedly accessed, the entire access process can be speeded up if at least a part of the data group can be accessed at a high speed.
Accordingly, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide data in a large data file stored in a predetermined storage means having a secondary storage medium such as a magnetic disk device. A data access method and program suitable for application to a process in which a data group existing in an arbitrary partial range in a data file is repeatedly accessed are provided. There is.

To achieve the above object, the present invention relates to a data file composed of a plurality of unit data stored in a predetermined storage means (hereinafter referred to as a first storage means) having a secondary storage medium such as a magnetic disk device. Based on identification information (hereinafter referred to as designated data ID) of the unit data (hereinafter referred to as designated data) to be accessed in the data file, the second storage that can be accessed at higher speed from the first storage means. A data access method for accessing the designated data after transferring data to a storage means, or a data access program for causing a computer to execute such access processing, wherein the method or computer comprises the following steps: It is a program for making it run.
That is, based on the designated data ID, the set of unit data (a set of unit data in the data file) for each predetermined number of data files (hereinafter referred to as the number of set unit data) from the top of the data file. In the case where each of the data groups is divided into each of the data groups (hereinafter referred to as data group IDs), the designated data is determined from the identification information (hereinafter referred to as data group IDs). A specified data group ID specifying procedure for specifying a specified data group ID that is the data group ID corresponding to the data group to which the data belongs;
Refer to the storage means (hereinafter referred to as third storage means) in which the data group ID and the data group address representing the start address of the data group in the first storage means are stored in association with each other. A data group address search procedure for searching for the data group address corresponding to the data group ID;
When the data group address corresponding to the designated data group ID is not found by execution of the data group address search procedure (that is, when the data group address is not stored in the third storage means), the first storage In the means, the data group address corresponding to the rearmost data group in the data file among the data group addresses stored in the third storage means, or when the data group address does not exist (that is, the third group If the data group address is not registered in the storage means, the start address of the data file is used as the access start address, and the subsequent unit data is sequentially accessed from the unit data existing at the access start address (the sequential Access to the unit data corresponding to the number of set unit data. Each time the data group address obtained by the access and the corresponding data group ID are associated with each other and additionally stored in the third storage unit, the data group to which the designated data belongs Data group address registration procedure to be performed until access,
A first data group transfer procedure for transferring the data group to which the designated data belongs when the data group address registration procedure is executed from the first storage means to the second storage means;
When the data group address corresponding to the specified data group ID is found by executing the data group address search procedure, the data group existing at the found data group address is transferred from the first storage means to the second storage unit. A second data group transfer procedure for transferring to the storage means;
A data access method having a second storage means access procedure for accessing the designated data in the second storage means, or a data access program for causing a computer to execute these procedures.
Here, as an example of the unit data and its identification information (for example, information on the relative position in the data file), the case of data for one record and its record number can be considered.

Further, a method having a data presence / absence determination procedure for determining whether or not the designated data exists in the second storage means, or a program to be executed by a computer, wherein the data group address search procedure is the data existence determination procedure. Thus, it can be considered that the processing is executed when it is determined that the designated data does not exist in the second storage means.
Further, a storage area of the third storage means may be expanded in accordance with an increase in the amount of information additionally stored by the data group address registration procedure.

According to the present invention, the following effects can be obtained.
First, in an initial state, there is no data in the second storage means or the third storage means constituted by a RAM or the like capable of high-speed data access.
Therefore, in the initial state, the data group address registration procedure sequentially accesses the subsequent data from the unit data located at the head address of the data file until the first data group to which the designated data belongs is reached. While performing data access in the storage means, the data group address and the data group ID corresponding to the data group address are associated with each other and additionally stored in the third storage means, and the designated data belongs The data group is transferred to the second storage means (high-speed memory).
Thereby, when the designated data ID is set thereafter, as long as the designated data corresponding to the designated data ID exists in the second storage means, the second storage means access procedure is executed to execute the second storage means access procedure. It is possible to access the designated data in the storage means at high speed.
Furthermore, even in the initial state, as shown in the above-mentioned Patent Document 2, all the data groups in the large-sized data file are pre-accessed and information on the start address (start point) is stored in advance. Instead, sequential access (sequential access) is performed only up to the data group to which the designated data belongs, so that the processing start delay can be minimized.
Moreover, since the correspondence relationship between the data group ID and the data group address is stored (registered) in the third storage means by executing the data group address registration procedure, the designated data is stored in the second storage. Even if it does not exist in the means, the designated data can be accessed at high speed.
That is, when the data group address of the data group to which the designated data belongs exists in the third storage means (when the address has already been registered), the data group existing at the data group address obtained by the search. Is quickly transferred to the second storage means, and the second storage means can quickly access the designated data.

In addition, even when the data group address of the data group to which the designated data belongs does not exist in the third storage means (when the address is not registered), at least the data file address among the already registered data group addresses. The data group to which the designated data belongs is transferred to the second storage means by sequentially following the addresses from the last side in the above, and high-speed access to the designated data in the second storage means Is possible.
Accordingly, it is not necessary to perform sequential access every time until the designated data is reached in the first storage means, and the entire access process can be speeded up.
Further, when the present invention is applied to a process in which repeated access to a data group existing in an arbitrary partial range in the data file is performed, the speed of data access becomes more remarkable.
That is, the second storage means stores (transfers) the data group to which the specified data in the data file belongs (a set of unit data existing in a part of the range). If the present invention is applied to a process in which a data group existing in an arbitrary partial range is repeatedly accessed, the second storage means access procedure does not access the first storage means, and the second storage means accesses the second storage means. The frequency of direct access to the storage means increases, which is preferable for speeding up the access processing.
In particular, it is determined whether or not the specified data exists in the second storage means (data existence determination procedure), and when it is determined that the specified data does not exist in the second storage means, the data If the group address search procedure is executed, the subsequent useless transfer of the data group (transfer from the first storage means to the second storage means) is eliminated, which is efficient.
Further, since it is sufficient to ensure only a capacity corresponding to the size of one data group as the second storage means, it is possible to avoid the problem that the performance of the entire system (computer) deteriorates.
Further, if the storage area of the third storage means is expanded in accordance with the increase in the amount of information additionally stored by the data group address registration procedure, the storage capacity of the third storage means is the minimum necessary. It can be suppressed to the limit.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that the present invention can be understood. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.
FIG. 1 is a block diagram showing a schematic configuration of the information processing apparatus X that executes the data access program according to the embodiment of the present invention, and FIG. 2 shows data that is executed when the information processing apparatus X executes the data processing program. FIG. 3 is a schematic diagram showing a memory configuration in the information processing apparatus X. FIG.

<Device overview>
Hereinafter, the configuration of the information processing apparatus X that executes the data processing program 30 according to the embodiment of the present invention will be described with reference to FIG.
Here, the data processing program 30 (an example of a data access program) is a plurality of record data (unit data) stored in the data storage unit 7 which is a large-capacity storage means such as a magnetic disk device provided in the information processing apparatus X. A specified record ID (an example of a specified data ID) that is identification information of record data to be accessed and information on a relative position in the data file. Is set, a program for causing the information processing apparatus X (an example of a computer) to execute processing for accessing record data corresponding to the designated record ID (hereinafter referred to as designated record data (an example of designated data)) It is.
The information processing apparatus X is configured with hardware by a computer such as a personal computer having the data storage unit 7 which is a large-capacity storage unit having a secondary storage medium such as a magnetic disk, and this is stored in advance in the storage unit. By executing the stored data processing program 30, it functions as a data access device. That is, the data processing program 30 is a program for causing the CPU 1 included in the information processing apparatus X (an example of a computer) to execute data access processing and function as a data access apparatus.

As shown in FIG. 1, the information processing apparatus X includes a CPU 1, which performs various arithmetic processes by executing various programs, a RAM 2, which is a high-speed memory in which programs executed by the CPU 1 and temporary storage data are expanded. ROM 3 in which programs such as BIOS executed by the CPU 1 are stored in advance, an input device 4 constituting input means such as a keyboard and a mouse, a display device 5 including a liquid crystal display panel, etc., and the CPU 1 that is executed or referred to A data storage unit 7, which is a storage means such as a hard disk in which the data processing program 30 and one or a plurality of data files 10 are stored, is connected through a bus 8.
Here, the RAM 2 is a storage unit (an example of a second storage unit) that can be accessed at a higher speed than the data storage unit 7 (an example of a first storage unit).
Further, the data file 10 stored in advance in the data storage unit 7 (an example of the first storage unit) is, for example, a CSV format (a comma-separated plurality of data) including a plurality of record data (an example of unit data). Each record data consisting of item data is a file in a format delimited by a line feed code.
The data processing program 30 is a program for causing the information processing apparatus X to execute processing for accessing each data constituting the data file 10.
In addition, the data storage unit 7 stores the specified record ID (for example, a record number) that is information specifying relative position in the data file 10 of the specified record data to be accessed with respect to the data processing program 30. ) Is also stored (not shown), which is a program that causes the information processing apparatus X to execute processing for setting (handing over) and various arithmetic processing based on data obtained by the data processing program 30.
Further, an OS (operation system) and a file system program for performing relay processing between each hardware constituting the information processing apparatus X and the data processing program 30 and various application programs including the data processing program are also included in the data. It is stored in the storage unit 7.

<About data access processing>
Next, the procedure of data access processing performed by the information processing apparatus X executing the data processing program 30 will be described using the flowchart shown in FIG. 2 and the schematic diagram of the memory configuration shown in FIG. Hereinafter, S1, S2,... Represent identification codes of processing procedures (steps).
The data processing program 30 is executed (on the OS) on the basis of an OS (operation system) that is a basic program executed by the information processing apparatus X, and the OS is stored in the data storage unit 7. It has a file system that performs data access management when accessing data. The data processing program 30 can access various data stored in the data storage unit 7 through the file system.
When the data processing program 30 is executed, a predetermined initial setting process is first performed (S1).
In this initial setting process, a data file selection process, a setting process for the number of divided records, a process for securing the work memory 21 and the index memory 22 (see FIG. 3), and the like are performed.
The data file selection process is a process of selecting a plurality of data files 10 existing in the data storage unit 7 to be accessed in the data access process. For example, file selection is performed according to information input by the user through the input device 4. Hereinafter, simply referring to the data file 10 indicates the data file 10 selected by the data file selection process.
The number of divided records is the setting of the number of records constituting the record group when the data file 10 is divided into a set of record data (hereinafter referred to as a record group) for a plurality of predetermined records from the beginning. Value. In this initial setting process, the number of classification records is set according to information input by the user through the input device 4, for example. Hereinafter, it is assumed that the value of the number of segmented records is m.
As shown in FIG. 3, the work memory 21 is a partial memory area secured in the RAM 2, and is an area to which one record group is transferred from the data file 10. The size of the area is a size obtained by multiplying the data size of one record of the data file 10 selected in the initial setting process by the number m of segmented records set in the initial setting process. Thus, the capacity of the work memory is very small compared to the size of the data file 10, so that the overall performance of the system (information processing apparatus X) is not particularly deteriorated.
The index memory 22 is a part of memory area secured in the RAM 2, which will be described in detail later. For each record group in the data file 10 in the data storage unit 7, the record group This is an area in which an ID is stored in association with a head address (a concept including pointer information indicating the address) where the ID is located. The area size of the index memory 22 is indefinite, and after an area having a predetermined size is secured in this initial setting process, it is expanded as necessary. It should be noted that the area of the index memory 22 may be secured in the data storage unit 7, for example.
In this initial setting process, a process for securing each area of the work memory 21 and the index memory 22 in the RAM 2 is performed.

Next, the setting process of the designated record ID, which is identification information representing the relative position information in the data file 10, of the designated record data that is the record data to be accessed in the data file 10 is executed (S2). ).
In this process, for example, by executing the data processing program, the specified record ID is determined according to record number information or the like input by the user through the input device 4, and the specified record ID is acquired from the data processing program. It is set by.
Next, when the specified record ID is set in step S2, the specified record group ID corresponding to the specified record ID is specified (S3).
The designated record group ID is a set of record data for the number of segmented records (an example of the number of set unit data) that is a predetermined number of records (= m) from the top of the data file 10. The record group corresponding to the record group to which the designated record data belongs among the record group IDs that are identification information representing the relative position information in the data file 10 of the code group when the record group is divided. This is an ID, which is specified in this process (an example of a record group ID specifying procedure).
For example, when the specified record ID is represented by a record number (0 to n) in which the first record in the data file 10 is 0, the value of the quotient obtained by dividing the record number by the number m of divided records is It may be specified as a specified record group ID.
For example, when the number of segmented records m = 1000 and the designated record ID is 2050, the value i of the designated record group ID is 2 which is a quotient of 2050 ÷ 1000.

Next, data for determining whether or not the specified record data exists in the work memory 21 (second storage means) of the RAM 2, that is, whether or not the record group to which the specified record data belongs exists. Existence determination processing (S4, S5: an example of data existence determination procedure) is executed.
In this process, it is determined whether or not the record group stored at that time in the work memory 21 is a record group to which the designated record data belongs. Here, the record group ID for identifying the record group stored at that time in the work memory 21 is stored in a predetermined work identification data area 23 (see FIG. 3) in the RAM 2, and the record It is checked whether or not the group ID matches the designated record group ID (= i) (S4). If there is a match, it is determined that the designated record data exists in the work memory 21 (Y side of S5), and if there is no match (including the case where no data exists in the work identification data area 23), the designated record It is determined that the data does not exist in the work memory 21 (N side of S5).

Next, when it is determined by the data existence determination process (S4, S5) that the designated record data does not exist, the record group ID (an example of the data group ID) and the start address (data group address of the data group address) The index memory 22 (an example of the third storage unit) stored in association with one another is referred to, and corresponds to the record group ID specified in step S3 (an example of the record group ID specifying procedure). A process of searching for the head address is executed (S6, an example of a data group address search procedure).
Here, the head address is information (pointer information or the like) indicating the head position of each record group in the data storage unit 7 (first storage means), and originally obtained from the file system provided in the OS. Information. That is, when the data file 10 stored in the data storage unit 7 is sequentially accessed (sequential access) from the position of the head address of the file (that is, the head address of the head record) through the file system, Each time data is accessed, the head address of the following data (here, record) is obtained from the file system.
Next, the result of the search in step S6 is determined (S7), and if the start address is not found by the search execution in step S6, among the start addresses of each of the record groups stored in the index memory 22, The data file 10 corresponding to the record group at the tail end is set as a starting address to be used later (S9). On the other hand, when such a head address does not exist (that is, the index memory 22 stores the head address). If there is no stored information, the leading address (address of the leading record) of the data file 10 is set as the starting point address (S10) on the N side of S8.

Further, when the start address is set, the subsequent data is sequentially accessed in the data storage unit 7 (first storage means) sequentially from the record data located at the start address, and Each time the record data for the number of divided records is accessed, the start address of the record group obtained through the file system by the access is associated with the record group ID corresponding thereto and additionally stored in the index memory 22 This process is performed until the last record data in the record group to which the designated record data belongs is accessed (S11, an example of a data group address registration procedure). At that time, the record group ID and the start address of the record group next to the record group to which the designated record data belongs are additionally stored in the index memory 22.
For example, when the specified record ID is specified by a record number, and the specified record group ID is specified as a quotient i obtained by dividing the record number by the number m of divided records, each record group ID = 0 to i + 1, The head addresses (“0, 3256, 17642, 33427,... In FIG. 3) of the record group corresponding to each are associated and stored in the index memory 22.
Thereby, as shown in FIG. 3, the index information in which the record group ID and the start address in the data storage unit 7 are associated with each record group in the area of the index memory 22 in the RAM 2 is as follows. The range from the first record data in the data file 10 to the next record data of the specified record data is registered (stored).
Here, in the process of step S11 (an example of a data group address registration procedure), the storage area of the index memory 22 in the RAM 2 is expanded and secured in accordance with the increase in the amount of information additionally stored by the process. The

Next, when the process of step S11 (an example of a data group address registration procedure) is executed, the record group (record data for m records) to which the designated record data belongs is transferred from the data storage unit 7 to the work. It is transferred to the memory 21 (S12, an example of a first aggregate data transfer procedure).
On the other hand, when the start address corresponding to the specified record group ID is found by executing the search (data group address search procedure) in step S6 (Y side of S7), the found start address is directly accessed, and the start address The record group (designated record group) located at (starting from the start address) is transferred from the data storage unit 7 to the work memory 21 (S12, an example of a second set data transfer procedure).
As a result, the specified record group can be directly accessed without performing sequential access in order from the start address of the data file for the record group in which the start address is registered in the index memory 22 in advance.
Here, when the record group is transferred to the work memory 21 (S 12), the record group ID corresponding to the transferred record group is stored in the work identification data area 23. As a result, the contents of the work memory 21 and the contents of the work identification data area 23 are matched.

Then, when it is determined that the specified record data exists in the work memory 21 by the data presence / absence determination process of step S5 (Y side of S5), or the record to which the specified record data belongs by executing the process of step S12 When the group is transferred to the work memory 21, the specified record data in the work memory 21 is accessed, and the specified record data is transferred to the data processing program (S13, second storage means). Example of access procedure). As a result, predetermined data processing is performed on the designated record data in the data processing program. For example, if the data processing program is a program that performs a process of graphing the data of the data file 10, the comma-deletion process that is a delimiter for the specified record data in the CSV format, and the comma separated Processing for converting text data representing a numerical value into numerical data, processing for graphing the data after numerical conversion, and the like are performed.
Thereafter, the processes in steps S2 to S13 described above are repeated every time the designated record ID is designated through the data processing program.

According to the data access processing described above, first, in the initial state, there is no data in the work memory 21 and the index memory 22 capable of high-speed data access. For this reason, when the specified record ID of the specified record data to be accessed is set, it is determined in the processes of steps S4 and S5 that the specified record data does not exist in the work memory 21 (N side of S5). In step S8, it is determined that the specified record group ID specified in step S3 is not found (N side of S8).
Therefore, in the initial state, the data storage is performed until the record group to which the designated record data belongs is accessed in order from the record data located at the head address of the data file 10 by the processing that proceeds to step S11 through step S10. While performing sequential access in the section 7, the processing of step S11 is performed in which the head address of each record group and the corresponding record group ID are associated and stored in the index memory 22, and the processing of step S12 is further performed. The record group to which the designated record data belongs is transferred to the work memory 21 (high-speed memory).
As a result, when the designated record ID is set (S2) thereafter, as long as the designated record data exists in the work memory 21, the process proceeds from the data presence / absence determination processing in steps S4 and S5 to step S13 and enters the work memory 21. Thus, the designated record data in the work memory 21 can be accessed at high speed.

Further, in the initial state, all the record groups in the large-size data file 10 are not preliminarily accessed and the information of the start address (start point) is stored in advance, but the specified record is processed by the process of step S11. Since sequential access is performed only up to the data group to which the data belongs, it is possible to minimize the processing start delay.
Moreover, the correspondence between the record group ID and the start address of the record group is stored (registered) in the index memory 22 by the registration process (S11) of the start address of each record group in the index memory 22, so that the designated record data Is not present in the work memory 21 (N side of S7), the designated record data can be accessed at high speed.
That is, when the head address corresponding to the designated record group ID exists in the search memory 22 (when the address has already been registered), the record group located at the head address obtained by the search in step S6 is promptly stored in the work memory 21. The data is transferred (S7 → S12), and high-speed access to the designated record data becomes possible in the work memory 21.

Even when the head address corresponding to the designated record group ID does not exist in the index memory 22 (when the address is not registered) (N side of S7), at least the head address of the record group already registered, the data file 10 (S9), the addresses are sequentially traced from there, and the record group to which the designated record data belongs is transferred to the work memory 21 (S11, S12). Access is possible.
As a result, it is not necessary to perform sequential access from the top data in the data file 10 every time until the specified record data is reached in the data storage unit 7, and the entire access process can be speeded up.
In particular, if the data processing program is applied to a process in which repeated access to a data group existing in an arbitrary partial range in the data file 10 is performed, as in the case of the data graphing process described above, data The speeding up of access becomes more remarkable, which is preferable.
That is, since the record group to which the designated record data in the data file 10 belongs (data group existing in a part of the range) is transferred to the work memory 21, it exists in an arbitrary part of the range of the data file 10. When a process for repeatedly accessing a data group is performed, the frequency of direct access to the high-speed work memory 21 without accessing the data storage unit 7 is increased, and the access process is further speeded up.

  The present invention can be used for a program or the like that performs access processing on a data file stored in a storage means.

1 is a block diagram illustrating a schematic configuration of an information processing apparatus X that executes a data access program according to an embodiment of the present invention. The flowchart showing the procedure of the data access process performed when the information processing apparatus X executes an execution data access program. 3 is a schematic diagram showing a memory configuration in the information processing apparatus X. FIG.

Explanation of symbols

X ... information processing apparatus 1 ... CPU
2 ... RAM
3 ... ROM
4 ... Input device 5 ... Display device 7 ... Data storage units S1, S2,... Processing procedure (step)

Claims (4)

Based on the designated data ID representing the identification information of the designated data that is the unit data to be accessed in the data file composed of a plurality of unit data stored in the predetermined first storage means, the first storage means A data access method for accessing the designated data after transferring data to a second storage means capable of high-speed access.
Identification information of each data group when the data file is divided into data groups each of which is a set of unit data corresponding to a predetermined number of set unit data from the beginning based on the designated data ID A designated data group ID identifying procedure for identifying a designated data group ID that is the data group ID corresponding to the data group to which the designated data belongs, from among the data group IDs;
Reference is made to third storage means in which the data group ID is stored in association with the data group address representing the start address of the data group in the first storage means, and the data group ID corresponding to the designated data group ID is stored. A data group address retrieval procedure for retrieving a data group address;
When the data group address corresponding to the specified data group ID is not found by execution of the data group address search procedure, the data group address stored in the third storage means is stored in the first storage means. The data group address corresponding to the data group at the rearmost side in the data file, or when there is no data group, the start address of the data file is set as the access start address, and the unit data existing at the access start address is used. Each time the unit data corresponding to the number of set unit data is accessed, the data group address obtained by the access is associated with the corresponding data group ID while sequentially accessing the subsequent unit data. The process of additionally storing in the third storage means is the designation A data group address registration procedure carried out until accessing the data group over data belongs,
A first data group transfer procedure for transferring, when the data group address registration procedure is executed, the data group to which the designated data belongs, from the first storage unit to the second storage unit;
When the data group address corresponding to the specified data group ID is found by executing the data group address search procedure, the data group existing at the data group address is transferred from the first storage means to the second storage. A second data group transfer procedure for transferring to the means;
A second storage means access procedure for accessing the designated data in the second storage means;
A data access method comprising: A data presence / absence determination procedure for determining whether or not the specified data exists in the second storage means;
2. The data access method according to claim 1, wherein the data group address search procedure is executed when it is determined by the data existence determination procedure that the designated data does not exist in the second storage means.   3. The data access method according to claim 1, wherein a storage area of the third storage unit is expanded in accordance with an increase in information amount additionally stored by the data group address registration procedure. Based on the designated data ID representing the identification information of the designated data that is the unit data to be accessed in the data file composed of a plurality of unit data stored in the predetermined first storage means, the first storage means A data access program for causing a computer to execute a process of accessing the designated data after transferring data to a second storage means capable of high-speed access.
Identification information of each data group when the data file is divided into data groups each of which is a set of unit data corresponding to a predetermined number of set unit data from the beginning based on the designated data ID A designated data group ID identifying procedure for identifying a designated data group ID that is the data group ID corresponding to the data group to which the designated data belongs, from among the data group IDs;
Reference is made to third storage means in which the data group ID is stored in association with the data group address representing the start address of the data group in the first storage means, and the data group ID corresponding to the designated data group ID is stored. A data group address retrieval procedure for retrieving a data group address;
When the data group address corresponding to the specified data group ID is not found by execution of the data group address search procedure, the data group address stored in the third storage means is stored in the first storage means. The data group address corresponding to the data group at the rearmost side in the data file, or when there is no data group, the start address of the data file is set as the access start address, and the unit data existing at the access start address is used. Each time the unit data corresponding to the number of set unit data is accessed, the data group address obtained by the access is associated with the corresponding data group ID while sequentially accessing the subsequent unit data. The process of additionally storing in the third storage means is the designation A data group address registration procedure carried out until accessing the data group over data belongs,
A first data group transfer procedure for transferring, when the data group address registration procedure is executed, the data group to which the designated data belongs, from the first storage unit to the second storage unit;
When the data group address corresponding to the specified data group ID is found by executing the data group address search procedure, the data group existing at the data group address is transferred from the first storage means to the second storage. A second data group transfer procedure for transferring to the means;
A second storage means access procedure for accessing the designated data in the second storage means;
Data access program for causing a computer to execute.

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