JPH05282186A - Method for constituting data base management system - Google Patents

Abstract

PURPOSE:To provide a data base management system constituting method capable of improving the usability of a data base management system, and executing the addition/deletion/subtraction of modules without stopping the system for driving the management system without interrupting it for 24 hours. CONSTITUTION:At the start (step 1) of the execution of a transaction using an individual module as a unit, using status that the transaction uses the module is registered (step 2) in a module management part as registering information, and at the end of the transaction execution (step 3)F the registering information is removed from a module management part (step 4) and a new module is added, or an old module is removed or substituted in the execution process of the transaction (step 5).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of constructing a database management system, and more particularly to a database management system composed of a plurality of modules for replacing modules constituting the system during transaction execution. Regarding the configuration method.

[0002]

2. Description of the Related Art A database management system is a system for permanently managing common data referenced or updated by a plurality of transactions without contradiction, and the common data to be managed is generally called a database.

The processing targeted by the database management system is a series of inquiries to the database and update processing for changing the contents of the database, and is generally called a transaction. A transaction accesses a disk device or the like that stores data to be processed. Furthermore, by processing transactions in parallel, a CPU (Central Processing Uni
Improve the usage efficiency of t). That is, while one transaction is reading data from the disk device, that transaction waits for input / output to / from the disk and releases the CPU, so that another transaction can use the CPU. Therefore, by processing a plurality of transactions in parallel, the usage efficiency of the CPU and the disk device that form the system is improved.

However, there is a case where the contents of the database become inconsistent when a transaction executing parallel processing updates the same data item in the database at the same time. Therefore, in a normal database management system, a mechanism called a concurrency control mechanism that controls the execution of transactions is provided so that there is no contradiction between transactions performing multiple parallel processes or the contents of the database operated by the transactions. It is controlled so that it does not occur. In addition to the above-mentioned parallel processing function, the database management system is a transaction execution control function that authorizes and controls the execution of transactions, and a magnetic disk of a database that is a function for maintaining and managing the database permanently and consistently. It is composed of multiple functional modules such as a storage and read-out mechanism.

Generally, the procedure for realizing a system composed of a plurality of modules is such that the individual modules are separately created, compiled, and then integrated by link operation, and the individual functional modules are realized independently. In particular, there is an interpreter method that calls when necessary. The compile method has an advantage that the execution speed is high because the rate of optimizing the sequence of instructions to be executed is high, and the compile method is usually used also in the database management system. However, the compile method has a problem that the system configuration lacks flexibility because the names of the modules to be linked and, in some cases, even the relationships between the modules are statically determined.

On the other hand, in the interpreter method, since the source module can be input and immediately executed, the determination of the module to be called can be delayed until the time of execution, and a flexible system configuration can be realized.

In recent years, the usage of application systems using a database management system has become more sophisticated, and there is an increasing need to provide services without interruption for 24 hours. Therefore, the suspension of the system has a great influence on the service, and it is desired to provide a database management system that can be maintained and managed without stopping the operation of the system. For example, when an error in a program that was not found at the start of system operation is discovered during operation, the incorrect part is corrected without stopping the system. In addition, system operation such that the system operation rate during operation gradually increases,
Furthermore, it is desirable that new modules can be added while the system is operating when new hardware needs to be added as the database grows in size and software accompanying it must be added. ing.

[0008]

However, the conventional database management system does not consider replacing modules, particularly software modules, during system operation, and does not replace or add modules.
The system must be stopped to perform the deletion. This is not simply due to the fact that the conventional database management system is realized by the compile method, and even if it is realized by the interpreter method, there is no means for knowing the trigger for replacing the module. Furthermore, it is a major factor that it cannot be guaranteed that there will be no inconsistency in processing before and after the modules are replaced.

Since a database management system normally processes a plurality of transactions in parallel, there is availability that a process becomes inconsistent when modules are replaced in the transaction execution process. Therefore, when the conventional database management system tries to replace the modules, it has to wait for the completion of execution of all the transactions being executed, and stops the operation of the system, or avoids the service degradation equivalent to the operation stop. I can't.

As described above, in the conventional database management system, if an error is found later in one of the modules, the database management system is stopped even if it is composed of a plurality of functional modules. However, there is a problem that the module replacement operation must be performed.

Also, the capacity of the database becomes so large that it cannot be stored in the existing disk device, and when the new disk device is added or the system components are changed, the service is interrupted and dealt with. There is also the problem that the system configuration must be changed by adding or replacing modules.

The present invention has been made in view of the above points,
In order to increase the availability of the database management system and operate the system without interruption for 24 hours, it is necessary to provide a method for configuring the database management system that enables addition / deletion or replacement of modules without stopping the system. To aim.

[0013]

FIG. 1 shows the principle of the present invention.

According to the present invention, there is provided a database management system comprising a transaction execution unit for controlling the execution of a transaction and a module group composed of a plurality of modules for processing the transaction under the control of the transaction execution unit, It is equipped with a module management unit that manages the usage status of the individual modules that make up the database management system. At the module management unit, when the execution of a transaction is started for each module, or the transaction starts using the module. At the point of time (step 1), the information that the transaction is using the module is registered in the module management unit as registration information (step 2), and at the end of the execution of the transaction (step 3), or
When the transaction finishes using the module (step 3), the registration information that registers the status used by the transaction is removed from the module management unit (step 4), and the transaction is executed. In the process, a new module is added, or at least one of the unused modules is deleted or replaced with another previously prepared module (step 5).

[0015]

The database management system of the present invention is a database management system comprising a transaction execution unit for controlling the execution of a transaction and a module group consisting of a plurality of modules for processing transactions under the control of the transaction execution unit. It has a module management unit that manages the usage status of individual modules, registers module usage when a transaction starts using the module, and when transaction execution ends or transaction ends module usage, By removing the information that the transaction used the module from the module manager, it is used by the transaction being executed, that is, before the end of the transaction is declared by the commit or rollback process. Because it can grasp the use status of joules, in a plurality of modules constituting a database management system in operation, it is possible to detect the module that is not currently used. Therefore, it is detected that the module to be deleted or replaced is in an unused state, and the unused module is deleted or replaced with another module.

Further, even when a new module is added, if there is a module affected by the addition of the module, the module is added when the affected module is in the unused state.

As described above, the database management system of the present invention can add, delete, or replace modules while executing transaction processing.
The number of times and the time to stop the system can be reduced.

[0018]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a block diagram of a database management system according to an embodiment of the present invention. The database management system 1 normally authorizes the execution of a transaction input from a terminal device or the like, and schedules the execution of a plurality of authorized transactions.
And a module group 4 of module groups M1 to M7 forming the database management system, and a module management section 3 for managing the module group with a module management table.

The module group 4 is generally composed of, for example, a parallel processing control module, a disk input / output module, a buffer management module, etc., and may be managed as a module including the transaction execution unit 2.

FIG. 3 is an example of a module management table that constitutes a module management unit according to an embodiment of the present invention. The module management table is a table for registering and managing a module identifier that identifies a module that constitutes the database management system and an identifier of a transaction that is currently using the module.

In the example of FIG. 3, three transactions, transaction T1 to transaction T3, are currently being executed. The transaction T1 uses modules M1, M3, M5, the transaction T2 uses modules M2, M3, and the transaction T3 uses modules M5, M6, M7.
Module M4 is not using any transactions.

The procedures of registration and deletion in the module management table will be described below by following the execution process of transactions. FIG. 4 is a flow chart for explaining a transaction execution process and module registration / deletion according to an embodiment of the present invention.

Step 41: The transaction is input to the transaction execution unit 2.

Step 42: The transaction execution unit 2 is a user who is authorized to use the transaction, and authorizes the execution of the transaction if the operation is for a database that has access rights. On the other hand, if a user who is not authorized to use the database operates it illegally or if it is an operation on a database for which there is no access right, transaction execution is not authorized.

Step 43: The authorized transaction operates according to the processing contents by using the module constituting the database management system. When using a module, the transaction execution unit 2 sends the module management unit 3 the identifier of the module to be used and the identifier of its own transaction. For example, in FIG.
, The transaction T1 is a module identifier M
1 and the transaction identifier T1 to the module management unit 3
To send to.

Step 44: The module management section 3
Whether the transaction uses the module for the first time from the combination of the module identifier and the transaction identifier (M1, T1) sent from the transaction execution unit 2,
Confirm whether to use the same module after the second time.

Step 45: If the transaction uses the module for the first time, register that the module is in use at the corresponding position in the module management table. Further, when the module management unit 3 receives a usage request for the same module from the second time onward, no particular operation such as registration in the module management table is performed.

Step 46: The module management section 3
If the requested module is in a usable state, or if the requested module is not in a usable state due to a module replacement operation or the like, use of the module is made to wait.

Step 47: Execute transaction (eg transaction T1 is module M1)
To execute the process).

Step 48: The transaction performs a commit operation or a rollback operation of the transaction when all the executions are completed.

Step 49: The module management section 3
Delete the usage information of the module by the transaction. That is, the transaction execution unit 2 sends to the module management unit 3 together with the transaction identifier that each transaction performs a commit operation or a rollback operation. As a result, the module management unit 3 deletes the registration information of the module used by the transaction from the module management table.

By the above-mentioned operation, the module used by the transaction being executed continues until the execution of the transaction is completed, that is, the transaction is
Each module is registered in the module management table until it is committed or rolled back.

Since a transaction that has ended once does not use the module with the same transaction identifier, the usage information of the module is deleted from the module management table of the module management unit 3 at the end of the transaction (transaction T1 is the module management unit. 3 will be deleted).

Next, the procedure for replacing the modules will be described.

A normal transaction for operating a database uses a read-only module that constitutes a database management system. That is, a normal transaction does not change the contents of the module. On the other hand, module replacement, addition, or deletion can be handled as an operation for changing the content of the module. Therefore, the two-phase lock method is used, which uses a shared lock that shares a module that is frequently used in parallel processing control in database processing with other transactions and an exclusive lock that uses the module exclusively with other transactions. Shows how to perform a swap operation consistently.

In general, in a database management system which processes a plurality of transactions in parallel, the operation for replacing the module is also a transaction in the database processing in order to guarantee that the module to be replaced is in an unused state. It can be treated in the same manner and can be processed by the two-phase lock method.

According to the above idea, a normal transaction locks a module when it is used, and releases the shared lock when the module is used, that is, when it is committed or rolled back. On the other hand, in a transaction for exchanging modules, an exclusive lock is applied to the modules to be exchanged. That is, when a normal transaction does not use a module (does not have a shared lock), the operation to replace the module is exclusively performed,
The exclusive lock is released when the replacement of modules is completed.

In the example of FIG. 3, assuming that there is only one transaction that replaces a module, a shared lock that a normal transaction locks is also shown in. In the example of the figure, only the module M4 is not currently used by a normal transaction. At this time,
A transaction can switch modules by locking the module M4 exclusively. The case where the requested module is not available, which is shown in the process of executing the transaction in step 36 of the flowchart of FIG. 4, means that the module is locked by the transaction for exchanging the module, and the module is exchanged. Is completed and the exclusive lock is released, the usage request of the module waits. The two versions, old and new, of the module to be swapped can coexist in the system. Since the processing required during the exclusive lock period can be limited to the operation of rewriting the module management table shown in FIG. 3, this operation can be performed in an extremely short time, and the influence on the execution of a normal transaction is small.

The procedure for replacing the modules will be described below.

FIG. 5 is a flow chart showing a procedure for replacing modules according to an embodiment of the present invention. Step 51: Load a new (replacement) module into memory. Step 52: Put an exclusive lock on the old (replaced) module on the module management table. If the lock used by a normal transaction cannot be acquired, wait at this stage until the lock can be acquired. Step 53: Update the management information in the module management table of the module management unit 3. Step 54: Release the exclusive lock secured in Step 52. Step 55: Delete the old module.

As described above, in the embodiment of the present invention, the method of registering the use of the module in the module management unit 3 at the time when the transaction actually starts the use of the module has been described. The module required for execution is determined when the transaction execution unit 2 authorizes the execution of the transaction, and the use of the module is collectively registered in the module management table of the module management unit 3. You can also In this case, a shared lock is secured for a plurality of modules at the same time.

Further, in the above-mentioned embodiment, an example in which the information on the module being used (corresponding to the shared lock) is deleted from the module management table of the module management unit 3 at the end of the transaction, that is, at the time of commit or rollback is shown. But,
When the use of the module is finished, the information on the use of the module can be deleted.

Further, even if the module unit constituting the database management system is different from the unit to be replaced or deleted, it is possible to replace a plurality of modules at once without conflict by locking the plurality of modules exclusively.

As a parallel processing control method other than the two-phase lock method, a method using a time stamp is also a parallel processing control method capable of guaranteeing that seriality is satisfied between a transaction for updating and a transaction for reading. If so, the module replacement during the execution of the normal transaction according to the present invention can be realized by allocating the module replacement to the transaction for updating and the normal transaction processing for the transaction for reading.

Further, in the present embodiment, the method of replacing the modules has been described. Similarly, for the addition of a new module or the deletion of an existing module, the processing for adding or deleting is assigned to the transaction for updating, and a normal transaction is performed. It can be realized by assigning the process to the transaction for reading.

[0047]

As described above, according to the present invention, in a database management system composed of a plurality of modules, it is possible to add, delete, or replace modules in the process of executing transaction processing. Therefore, the number of times the system is stopped and the time can be significantly reduced.

Furthermore, since the system configuration can be changed during operation of the database management system, the availability of the system can be greatly improved.

[Brief description of drawings]

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

FIG. 2 is a configuration diagram of a database management system according to an embodiment of the present invention.

FIG. 3 is a diagram showing an example of a module management table forming a module management unit according to an embodiment of the present invention.

FIG. 4 is a flowchart illustrating a transaction execution process and module registration / deletion according to an embodiment of the present invention.

FIG. 5 is a flowchart showing a module replacement procedure according to an embodiment of the present invention.

[Explanation of symbols] 1 database management system 2 transaction execution unit 3 module management unit 4 module group

Claims (1)

[Claims] 1. A database management system comprising a transaction execution unit for controlling the execution of a transaction and a module group composed of a plurality of modules for performing transaction processing under the control of the transaction execution unit. The system includes a module management unit that manages the usage status of the individual modules that make up the system, and when the execution of a transaction is started for each individual module or when the transaction starts using the module, the transaction Registers the information using the module in the module management unit as registration information, and the transaction is used by the transaction at the end of execution of the transaction or when the transaction finishes using the module. The registered information that has registered the existing status is removed from the module management unit, and in the process of executing the transaction, a new module is added, or at least one of the unused modules is deleted, or A method for configuring a database management system, characterized in that it is replaced with a module prepared in advance.