JPH0214338A - Data base access method - Google Patents

Abstract

PURPOSE:To obtain a response corresponding to a basic direct access method (BDAM) and to improve the response of a CAD system by enabling a direct access concerning an access such as reading and updating, etc., to an existent file. CONSTITUTION:On the basis of a reading record number (n), which is designated by reading and updating commands, and the number of records (a) per track of a file information control table 12, the positioning command of a file is prepared and further, on the basis of a designated reading numbers of records (m), a reading buffer address Addr, a track number (b) per cylinder of the file information control table 12 and a record length (c), a reading channel command for the designated number of records (m) is prepared. Then, the existent file is accessed. A command is prepared to position a head to a final record position when an additional command is received. Then, the count part and key part of the additional record are prepared and additional writing is executed.

Description

[Detailed Description of the Invention] [Summary] Regarding the database access method that efficiently creates files, accesses the created files, and performs additional processing on existing files, access to existing files is performed using the basic direct access method (BDA).
M) A response equivalent to the basic sequential access method (BSAM) is obtained, and additional processing is performed using a sequential fixed-length file that stores graphic data and a management file that stores file information. Prepare a table, and when receiving an access command for an existing file or an additional command, create a positioning command that refers to the management table in the channel command generator to specify the file access position, and a channel command that corresponds to the access content. Configure files for fast access.

[Field of Industrial Application] The present invention relates to a database access method that efficiently creates files, accesses created existing files, and performs additional processing on existing files.

In a CAD system, graphic data prepared in a file as a database is accessed when displaying or editing shapes, but the amount of data is enormous, and access must be performed at high speed to improve response. This is required.

[Prior art] As a conventional database access method, a virtual memory access method (Virt.
ual Storage Access Meth
od) and additional processing are not possible as is.
sMethod) is provided.

However, these database access methods are very inefficient when adding new data to existing files.

For example, in the basic direct access method (BDAM) addition processing, after closing the -degree file, the basic sequential access method (Basic 5equentiaACCeSS
It is necessary to reopen the file as a Method) to enable additional processing, and then reopen the file as a basic direct access method (BDAM) after performing additional processing.

The reason for this is that conventional database access methods are designed to efficiently access existing databases at the expense of additional processing.

[Problems to be Solved by the Invention] However, in CAD systems, database addition processing is frequently performed, so currently a virtual memory access method (VSAM) that can perform additional processing is used. There is a problem with the response when adding data to an existing file.

The present invention was made in view of these conventional problems, and access to existing files is performed using the basic direct access method (
The object of the present invention is to provide a database access method capable of high-speed access, which can obtain a response equivalent to the basic sequential access method (BSAM) and additional processing can obtain a response equivalent to the basic sequential access method (BSAM).

[Means to solve the problem] FIG. 1 is a diagram explaining the principle of the present invention.

In FIG. 1, first, in the database access method of the present invention, a sequential fixed length file 10 storing graphic data and a file information management table 12 storing file information of this sequential fixed length file 10 are prepared. be done.

The file information management table 12 stores the number a of records per track in the sequential fixed length file 10, the number b of tracks per cylinder, the record length C, and the final record number max.

When an access command for an existing file or an addition command for an existing file is received from the host, the channel command generation unit 14 refers to the file management table 12 and creates a positioning command for specifying the access position of the sequential fixed-length file 10. , create a channel command corresponding to the access content and perform file access.

Examples of access commands for existing files include Read, ) :l:l? Land is updated (Upda)
There is a te) command.

When this read or update command is received, a file positioning command is created based on the read record number n specified by the command and the number of records per track a of the file information management table 12, and a file positioning command is created based on the read record number n specified by the command. Create a read channel command for the specified number of records (1) based on the read record number m, the read buffer address Addr, the number of tracks per cylinder in the file information management table 12, and the record length C, and access the existing file. .

On the other hand, when an add command is received, the head is moved to the final record position based on the number m of additional records specified by the add command, the number a of records per track in the file information management table 12, and the final record number maX. After creating a positioning command for positioning, and creating the count part and key part of the additional record by referring to the file information management table 12, create an additional channel command to perform additional writing for each Lou code of the specified additional record. Create them sequentially and perform additional processing.

[Operation] In the database access method of the present invention, when accessing existing files, a response equivalent to that of the conventional basic direct access method (BDAM) can be obtained;
On the other hand, for additional processing on existing files, a response equivalent to the conventional basic sequential access method (BSAM) can be obtained, greatly improving the response of CAD systems that access large amounts of graphic data and perform graphic display and editing processing. High-speed access can be achieved.

[Example] Figure 2 shows the time of reading (Read) and updating (Update)
FIG. 2 is an embodiment configuration diagram showing an embodiment of the present invention by taking an example of access processing at a time.

In FIG. 2, 10 is a sequential fixed length file using a magnetic disk, 12 is a file information management table storing file information of the sequential fixed length file 10, and 1
4a is a channel command generator that generates positioning commands and read channel commands for the sequential fixed-length file 10;

The sequential fixed length file 10 has the file structure shown in FIG.

Figure 3 shows the phi for one cylinder of a magnetic disk.

This figure shows the number of tracks indicated by the track numbers ob and b, and each track has, for example, five record areas, so the number of records a per track is a=5. Become. Furthermore, the record length of the record provided on each track is C, and furthermore, in the case of FIG. 3, since data has already been written up to the second record of track number (b-1), track number ( b-
1> is the final record number max, and the area after it is an empty area.

Referring again to FIG. 2, table information management table 1
2 stores the number of records per track 811, the number of tracks per cylinder b, the record length C1, and the final record number max as table information of the sequential fixed length file 10 shown in FIG.

Next, the access process when receiving a read command or an update command from the host will be explained with reference to the operational flow diagram of FIG.

For example, a read command (Read) is issued from the host, and by decoding this read command, Re is issued in step S1.
An ad request is determined. Also, by decoding the read command, the read record number n specified by the read command,
The number m of records to read and the read buffer address Addr are obtained.

In the next step S2, the channel command generator 14a refers to the file information management table 12 and reads the number of records a per track.

Subsequently, in step S3, the channel command generator 14
a specifies the read start position of the sequential fixed length file 10 based on the number of records per track a read from the file information management table 12 and the request record number (instruction record number) n specified by the read command. Create a positioned command. This positioning command is a command for specifying the track and code of the sequential fixed-length file 10.

In this way, the positioning command for locating the file position specified by the read command for the sequential fixed-length file 10 is created based on the management information in the file information management table 12. There is no need to perform unnecessary input/output to obtain the positional command, and positional commands can be generated efficiently.

Subsequently, in step S4, the channel command generator 14a reads the number of tracks per cylinder and the record length C from the file information management table 12,
The number of tracks per cylinder read in the next step S5, the record length C1, the number of requested records n specified by the read command, and the number m of records specified from the record positioned in step S3 from the buffer 7 address Addr. A read channel command is created, and file access is executed based on the read channel command in step S6.

As a result, it is possible to perform the record reading process instructed in response to a read or update command from the host with a single input/output operation. In this way, records instructed by the host can be processed by one input/output by transmitting commands and channel commands to the channel command generator 14a.
This is because you can create the file yourself and read it directly into the request source's buffer without having to have a buffer for file access in the access routine.

As a result, in the process of reading or updating an existing file according to the present invention shown in FIGS. 2 and 4, a response equivalent to the conventional basic direct access method (BDAM) can be obtained.

FIG. 5 is a block diagram showing an embodiment of the present invention regarding access processing for additional commands from the host.

In FIG. 5, a sequential fixed-length file 10, a file information management table 12, and a channel command generator 1
4a is the same as in the case of FIG. 2, and in the additional processing of FIG.
Number of records per track a, final record number max
and record length C to perform additional processing access.

FIG. 6 shows an operational flow diagram of additional processing in the embodiment of FIG.

In FIG. 6, when an additional command is issued by the host, a request for additional processing is determined in step S1 by deciphering the additional command, and the process proceeds to step S2. Incidentally, when decoding the additional command, as shown in FIG. 5, the number m of additional decodes and the address Addr of the additional buffer 7 are decoded.

In step S2, file information management table 1
2, the number of records per track a and the final record number max are read, and in the next step S3, a positioning command is created to position the head of the sequential fixed length file 10 at the final record position.

Subsequently, in step S4, the file information management table 12 is referred to to create a count section and a key section of the additional record.

Next, the buffer 7 address A specified in step S5
dd and the record length C obtained from the file information management table 12, an additional channel command for each additional record, that is, a write channel command is created, and additional writing for the Lou code is executed in step S6. In step S7, it is determined whether or not writing of all additional records has been completed. If writing of all additional records has not been completed, the process returns to step S4 and the count section and key of the next additional record are determined. Create a section and do the same in step S5. In S6, the next additional record is written.

Then, in step S7, when writing of all additional records corresponding to the number of additional decodes m is completed, the series of additional processing ends.

In such additional processing of the present invention, a high-speed response equivalent to that of the conventional basic sequential access method (BSAM) can be obtained.

Of course, the additional processing shown in FIGS. 5 and 6 can be applied as is to the so-called database creation processing in which data is written from the beginning to the sequential fixed-length file 10, and the creation processing can also be applied to the conventional basic sequential access method (BSAM). You can get a fast response.

Furthermore, when the additional processing shown in Figs. 5 and 6 is completed,
Last record number ma of file information management table 12
x is incremented by the number m of newly added additional records and is changed to max = max + m in preparation for the next addition process.

In the above embodiment, reading processing and updating processing were taken as examples of basic file access, but
Processing that generates a large amount of input/output when accessing a database,
For example, for load processing, save processing, zooming processing, etc., the channel command generator 14 similarly creates position commands and channel commands corresponding to the contents of each command, using the conventional basic direct access method (BDAM).
You can get a fair amount of response.

[Effects of the Invention] As explained above, according to the present invention, direct access is possible for reading, updating, etc. to existing files, so that the conventional basic direct access method (B
DAM), and for addition processing to add data to existing files and creation processing to create a new database, responses equivalent to the conventional basic sequential access method (83AM) were obtained, and the display of figures was It is possible to achieve high-speed access that greatly improves the response of a CAD system that handles a large amount of data for editing processing.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the principle of the present invention; Fig. 2 is an example configuration diagram at the time of Read/Llpdate; Fig. 3 is an explanatory diagram of a sequentially organized fixed-length file; Fig. 4 is an illustration of the Read/Update processing of the present invention. Operation flow diagram; FIG. 5 is an explanatory diagram of an embodiment at the time of ADD; FIG. 6 is an operation flow diagram of additional processing of the present invention. In the figure, 10: Sequential fixed length file (DISC) 12: File information management table 14: Channel command generator 14a: Channel command generator IN: eLtRead/Update operation 1 file 0-54
Fig. 4, P-<F month σ error 1 and η lo + D flow diagram Fig. 6

Claims (1)

[Claims] Sequential fixed-length file storing graphic data (10)
and the file information of the sequential fixed length file (10) as the number of records per track a in the sequential fixed length file (12), the number of tracks per cylinder b,
It has a file information management table (12) stored in the format of record length c and final record number max; when receiving an existing file access command or addition command from the host, the channel command generation unit (12)
In step 4), a positioning command for specifying the access position of the sequential fixed-length file (10) is created by referring to the file information management table (12), and a channel command corresponding to the access content is created to access the file. A database access method characterized by accessing the database. (2) When a read or update command is received from the host as an access command for an existing file, the read record number n specified by the command and the number of records a per track in the file information management table (12) A file positioning command is created based on the file positioning command, and the specified number of read records m and read buffer address Add
2. The database access method according to claim 1, wherein read channel commands for the designated number of records m are created based on r, the number b of tracks per cylinder, and the record length c of the file information management table (12). . (3) When an additional command is received from the host, based on the number of additional records m specified by the additional command, the number of records per track a and the final record number max in the file information management table (12). After creating a positioning command to position the head at the final record position, and creating a count section and a key section for additional records by referring to the file information management table (12), additional writing is performed for each additional record. 2. The database access method according to claim 1, further comprising sequentially creating additional channel commands for performing the following steps.