JPH04139545A - Data base updating processing system - Google Patents

Abstract

PURPOSE:To prevent the reference processing to other programs from being kept waiting for a long time even at execution of an application program which updates a large number of data base records by setting a local buffer of a data base buffer area exclusive for the application program against an application program which updates plural data base records. CONSTITUTION:The reference updating processing is applied to the data base records 10 from the application programs 1 and 2 via a data base control system 3. A local buffer 7 is provided in a memory 4 to the processing of the program 1 and the data base records 12 which are updated by the program 1 are copied to the buffer 7 from a global buffer 56. Thus the records 12 are updated in the buffer 7. As a result, the time during which other programs are unable to refer to the record 12 to be updated is shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a database update processing method, and in particular, in a database system where multiple application programs refer to and update multiple database records respectively, the present invention relates to a database update processing method. The present invention relates to a database update processing method that updates a plurality of database records by shortening the exclusive period in an exclusive mode in which it is impossible.

[Conventional technology]

Conventionally, in database systems, database records of shared resources are stored so that each application program can refer to and update them arbitrarily without confusion.
Processing is performed with mutual exclusion. For database records that are referenced and updated by multiple application programs, each application program's processing is
For reference processing, so that they can be referenced at the same time,
Reference processing is performed with exclusive access in shared mode that can be referenced from other application programs. In addition, in the case of update processing, in order to make the database record exclusive, the update processing is performed in an exclusive mode that cannot be referenced from other application programs.

When updating multiple database records, when searching for the database record to be updated, if the search is performed with exclusive mode, the reference processing in other application programs will be forced to wait unnecessarily.
If you perform a search process with exclusion applied in shared mode, you must change to exclusive mode after searching for the database record to be updated, and during this time, if another application program applies exclusion in exclusive mode, etc. However, there is a problem in that deadlocks are more likely to occur.

While searching for database records to update,
As an exclusive control method that does not require other application programs to wait for reference and is less likely to cause deadlock, there is a proposal for ``Shared Resource Exclusive Control Method J'' described in, for example, Japanese Unexamined Patent Publication No. 63-124139. In this shared resource exclusive control method, the sharing mode is divided into reference sharing mode and update sharing mode. Reference processing for updating is exclusive in update sharing mode, and reference processing without updating is exclusive in reference sharing mode. processing.

This allows reference processing for updating and reference processing for non-updating to be referenced at the same time. In the reference sharing mode, waiting is performed only when exclusion is already applied in the exclusive mode, and if reference processing for updating is performed, the references cannot be made at the same time. In the update sharing mode, a wait is made if an exclusion is already applied in the update sharing mode or exclusive mode. Note that when updating a database record, update processing is performed after changing the update sharing mode to exclusive mode.

By performing such exclusive control, reference processing that is not updated by other application programs is not made to wait while a database record to be updated is searched, so that the waiting time for reference processing is shortened.

[Problem to be solved by the invention]

By the way, in the above-mentioned conventional technology, the exclusion of each database record is normally released when the application program that has applied the exclusion is terminated. When updating a database record, exclusion is applied in exclusive mode, so other application programs cannot reference the database record until the application program ends.

Also, in the "shared resource exclusive control method" described in Japanese Patent Application Laid-Open No. 63-124139, during reference (search) processing for updating, reference processing of other application programs that do not have to be updated is not made to wait. When updating subsequent database records, apply exclusive mode and
Since the exclusion is not released until the application program ends, other application programs cannot refer to the database record during that time.

Therefore, when running an application program that updates a large number of database records, many database records will be locked in exclusive mode.
Further, there is a problem that it takes a long time to release the exclusion, and the process of referring to other application programs takes a long time.

The present invention has been made to solve the above problems.

SUMMARY OF THE INVENTION An object of the present invention is to provide a database update processing method in a database system that does not allow reference processing of other application programs to remain open for a long time even when an application program that updates a large number of database records is executed. It is in.

[I! Means to solve the problem]

In order to achieve the above object, the database update processing method of the present invention reads a plurality of database records from a medium storing the plurality of database records into a database buffer on memory. II number of application programs instruct each to exclude database records.

In a database system that references and updates multiple database records, a local buffer in the database buffer area dedicated to the application program is set for an application program that updates multiple database records, and multiple database records of the application program are updated. The update process involves securing exclusive access to the database record to be updated in a shared mode that can be referenced from other application programs, copying the database record from the database buffer to the local buffer, and then copying the database record on the local buffer. After updating, when the application program ends, all the database records updated by the application program on the database buffer are secured in exclusive mode that cannot be referenced from other application programs, and the database records on the database buffer are The present invention is characterized in that the database record is rewritten with an updated database record on a local buffer, the exclusion of the database record is released, and the database record update process is completed.

[Effect]

In a database system, multiple application programs refer to and update multiple database records. For this reason,? Multiple database records are read into a database buffer in memory from a medium storing Ii number of database records, multiple application programs instruct each database record to be exclusive, and refer to and update the multiple database records individually. do.

For an application program that updates a plurality of database records, a local buffer in a database buffer area dedicated to the application program is set, and the application program updates the plurality of database records.

When updating multiple database records, the application program secures exclusive access to the database record to be updated in a shared mode that can be referenced by other application programs, and transfers the database record to be updated from the database buffer to the local buffer. make a copy. Then, the plurality of database records are updated by the application program on the local buffer. During this time, the database record being updated is exclusive in shared mode so that it can be referenced from other application programs, and moreover, it is exclusive only when copying, so it can be referenced from other application programs at any time. .

When the application program is terminated, all database records updated by the application program in the database buffer are
Exclusion is ensured in an exclusive mode that cannot be referenced from other application programs, and the database record in question on the database buffer is rewritten with the updated database record on the local buffer. Then, the exclusion of the database record in the database buffer is released, and the database record update process is completed.

As a result, even when running an application program that updates a large number of database records, each database record update is performed in the local buffer by exclusive use in J-enabled mode, and each copied database system is Update processing is in progress, and other applications are being updated.

Application program reference processing will not be delayed for a long time. Also, when the application program does not terminate normally, the database record must be returned to the state before the update, but here, the contents of the database record in the local buffer of the termination process are rewritten to the database buffer C database record. If not, the database record before being updated remains as it is, and no special processing is required.

〔Example〕

Hereinafter, one embodiment of the present invention will be specifically described using the drawings.

FIG. 1 is a block diagram showing the configuration of a database system according to an embodiment of the present invention. In Figure 1,
1 is an application program that updates a plurality of database records, and 2 is an application program that refers to the database records. Further, 3 is a database management system, 4 is a memory, 5 is a processing unit, and 6 is a database management system.
7 is a global buffer of the database buffer, 7 is a local buffer which is a dedicated area of a part of the database buffer, 8 is a local buffer evacuation medium of the disk device, and 9 is a database storage medium of the disk device.

The database storage medium 9 includes database records 1
0 is stored, and when performing reference processing and update processing of the database record 10, a plurality of database records 10 are read at once into the global buffer 6 on the memory 4, and the plurality of database records are stored in the global buffer 6. Database processing is performed in a state where 11 is stored.

For example, the application program 2 only references the database records 11, and the application program 1 performs a process of updating the database records 10 in large quantities. Database record 1 from application program 1 and application program 2
The reference update process to 0 is performed via the database management system 3. For the processing of the application program 1, first, a local buffer 7 is provided on the memory 4, the database record 12 to be updated by the application program 1 is copied from the global buffer 6 to the local buffer 7, and the copied local buffer 7 is
Above, the database record 12 is updated. Further, the local buffer saving medium 8 provides a storage area for saving the contents when the local buffer 7 is full.

Next, each process of reference processing, update processing, and synchronization point processing of database records of processing elements by the database management system in each application program will be explained.

FIG. 2 is a flowchart showing the processing flow of database record reference processing. Reference processing is, for example,
Application program 2 is global buffer 6
This is a reference process performed on the database record 11 read by. Reference processing is performed by exclusive use in a shared mode that allows reference from other application programs.

First, in processing step 21, exclusive access is applied to the database record on the global buffer in shared mode,
In processing step 22, the database record to be referenced is set in the output field, and the reference processing is completed.

FIG. 3 is a flowchart showing the processing flow of database record update processing. This update process includes, for example, a first update process performed on the database record 12 copied onto the local buffer 7 by the application program 1, and a second update process performed on the database record 11 on the global buffer 6. is configured so that it can be selected as an option.

In the update process, first, in process step 3o, the option of using a local buffer is determined. If there is no option, in processing step 37, exclusive mode is applied to the database record on the global buffer, and in the next processing step 38, processing is performed to update the contents of the database record on the global buffer, and the update processing is performed. finish. In this case, for the database record that has been updated, the synchronization point process (Figure 4) is performed to complete the update process for other database records that are updated at the same time as the update process for the database record. During this period, exclusive mode will not be released. Therefore, the database record that has been updated is an intermediate result, and reference from others is prohibited.

On the other hand, if the option is determined in processing step 30, if there is an option, then in the next processing step 31, the database record on the global buffer is excluded in the shared mode. Next, in processing step 32, it is determined whether the database record exists on the local buffer or local buffer save medium. If the database record to be updated exists, the process proceeds to step 36, where the database record is updated on the local buffer. On the other hand, if the database record does not exist in the local buffer or local buffer save medium, in the next processing step 33, it is determined whether or not there is space in the local buffer, and if there is no space, the next processing step In step 34, the code on the local buffer is saved to the local buffer save medium to secure free space, and then the process proceeds to step 35. If there is space, the process directly proceeds to process step 35, and the update target on the global buffer is saved. Copy the database records to free space in the local buffer. Next, in processing step 36, the database record to be updated is updated on the local buffer, and the processing ends.

In the update process when there is an option to use the local buffer, the database record on the global buffer is simply copied, and the process is performed with shared mode exclusion similar to the reference process. Therefore, in this case, the database record on the global buffer remains in its previous state without being updated, and can be referenced by others.

FIG. 4 is a flowchart showing the processing flow of database record synchronization point processing. This sync point process is
For example, this is a process for ending updates of a plurality of database records that the application program 1 simultaneously performs. This process includes canceling the exclusive mode applied to the database record to be processed.

In the case of this synchronization point processing as well, first, in processing step 41, the option of using a local buffer is determined. If there are no options, then in processing step 45,
Only releases the exclusive access of the relevant database. Also,
If there is an option to use the local buffer, in processing step 42, database records on the global buffer corresponding to all database records existing on the local buffer and the save medium are excluded in exclusive mode. Next, in processing step 43, the database record on the local buffer is copied to the global buffer, and further, in processing step 44, the database record on the save medium is copied to the global buffer. Then, processing step 4
In step 5, the exclusive is released. As a result, the database record updated on the local buffer is reflected as a database record on the global buffer that can be referenced from others.

Next, a description will be given of database update processing in an application program in which such reference processing, update processing, and synchronization point processing for database records are performed at any time.

FIG. 5 is a diagram illustrating an example of database update processing when there is no option to use a local buffer in the application program.

The application program 1 that updates a large number of database records performs database record A update processing 51 . Database record B update process 52. and synchronization point processing 53 are performed sequentially to update the database.

First, when updating processing 51 of database record A is performed, as a process of the database management system 3, in step 51a, exclusiveness is secured for database record A in exclusive mode, and in the next step 51b, from database record A11a on global buffer 6. a′
Update to. Similarly, when the update process 52 of the database record B is performed, the database record B is updated in step 52a as a process of the database management system 3.
In the next step 52b, database record B on the global buffer 6 is secured in exclusive mode.
is updated from b to b'. Next, when the synchronization point process 53 for ending the application program 1 is performed, the database management system 3 processes the database record A and the database record B in step 53a.
Release the exclusion with.

If application program 1 does not terminate normally, the database record on global buffer 6 must be returned to the state before the update, so after updating database record A until application program l terminates normally, , In order to guarantee the contents of database record A, update processing is performed in exclusive mode so that other application programs cannot refer to it. In this way, in processing when the local buffer use option is not specified, exclusive access to database record A is secured in exclusive mode from the time of an update request for database record A until the time when application program L is processed at the same time. Therefore, other application programs cannot refer to database record A during that time.

Therefore, in order to shorten the time it takes to secure exclusive access to database records in exclusive mode, in other words, to shorten the time when other application programs cannot reference them, specify the option to use local buffers and perform database update processing. conduct.

FIG. 6 is a diagram illustrating an example of database update processing when the application program has an option to use a local buffer.

An application program l that updates a large number of database records performs update processing 61 for database record A in a series of processes. Database record B update process 62. and synchronization point processing 63 are performed sequentially to update the database. In this case, for the application program 1 that updates database record A and database record B, the local buffer 7
will be provided.

When the application program 1 executes the update process 61 of the database record A, the database management system 3 processes in step 61a to apply exclusion to the database record A in the shared mode, and in the next step 61b, the global buffer 6 Copy the contents of database record A above to local buffer 7. In the next step 61c, the contents of the database record A are transferred from a to a' on the local buffer 7.
Update to. Similarly, when the database record B update process 62 is performed, the database management system 3 processes in step 62a to apply exclusion to the database record B in the shared mode, and in the next step 62b, updates the database record B on the global buffer 6. Copy the contents of B to local buffer 7. In the next step 62c, the contents of database record B are updated from b to b' on the local buffer 7. When the synchronization point process 63 for ending the application program 1 is performed, as a process of the database management system 3, in step 63a, database record A and database record B are excluded in exclusive mode. Next, in step 3b, data bell 2 record A and database record B on the global buffer 6 are updated with the contents of database record A and database record Bσ on the local buffer 72.Then, in the next step 63c, the database Release M1 and others of record A and database record B.

Even in this update process, if application program 1 does not terminate normally, the database record on global buffer 6 will be changed to application program 1.
However, in this case, until application program 1 terminates normally, the database records on global buffer 6 are only referenced and copied, but not updated, so the application program is not updated normally. Even if the process does not end, there is no need to perform any processing to return the database record. Therefore, exclusive mode is applied to database records only when the global buffer 6 is updated with the contents of the database records in the local buffer 7 at the end of the application program.

In this way, when database update processing is performed with the local buffer use option specified, database record A is secured in exclusive mode only during synchronization point processing, so database records cannot be accessed from other application programs. The time when it cannot be referenced has become shorter.

The present invention has been specifically explained above based on examples, but
It goes without saying that the present invention is not limited to the embodiments described above, and can be modified in various ways without departing from the spirit thereof.

〔Effect of the invention〕

As described above, according to one aspect of the present invention, while an application program that updates a large number of database records is running, the exclusive period in exclusive mode is shortened,
This has the effect of reducing the time during which other application programs cannot reference the database record to be updated.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a database system according to an embodiment of the present invention, FIG. 2 is a flowchart showing the processing flow of database record reference processing, and FIG. 3 is a database record update process. Flowchart showing the processing flow of processing. The fourth direction is a flowchart showing the processing flow of database record synchronization point processing. FIG. 6 is a diagram illustrating an example of database update processing when an application program has an option to use a local buffer. In the figure, 1... Application program, 2... Application program, 3... Database management system, 4... Memory, 5... Processing device, 6...
・Global buffer, 7...Local buffer, 8
...Local buffer save medium, 9...Database storage medium.

Claims (1)

[Claims] 1. Read multiple database records from a medium storing multiple database records into a database buffer in memory, and multiple application programs instruct each to exclude the database records and refer to the multiple database records individually. In the database system to be updated, a local buffer in the database buffer area dedicated to the application program is set for the application program that updates multiple database records, and the update processing of multiple database records of the application program is performed in the database to be updated. Secure exclusive access to the record in shared mode so that it can be referenced from other application programs, copy the database record from the database buffer to the local buffer,
The database record is updated on the local buffer, and when the application program ends, all the database records updated by the application program on the database buffer are updated.
Secures exclusion in exclusive mode that cannot be referenced from other application programs, rewrites the database record in the database buffer with the updated database record in the local buffer, cancels the exclusion of the database record, and A database update processing method characterized by terminating update processing.