KR19990068337A - Database Transaction Recovery with transaction completion key - Google Patents

Abstract

The present invention completely recovers the database management server without partially losing the commands constituting the transaction. It is about how to perform. More specifically, when a server function is restored after a server function is stopped due to a system error of the server while a transaction composed of several commands is being executed, a specific part of the command within the transaction may have already been executed. In this case, the present invention relates to a method of guaranteeing execution while maintaining consistency among instruction units in a transaction by performing the remaining instructions that were not completed in the transaction.

To this end, the present invention specifies a command called a complete key in a transaction. When the transaction that contains this command key is suspended due to an error in the server system during execution, and then the server is restored again, if the execution key command is executed before the system stops, the data by the previously executed command is restored. After that, the remaining instructions that could not be executed in the transaction are also executed to complete the execution of the transaction that was stopped due to a system error. However, if the transaction was not executed up to the execution key position before the system was stopped, all data changes caused by the execution of the transaction will be erased (RollBack). Through this, the database management server can guarantee not only the integrity of data at the transaction level, but also the organic performance between the unit instructions constituting the transaction and the performance of the transaction itself. This approach differs from the computing environment of the past, where only transaction units were considered meaningful work in a server-controlled usage environment, where instructions that constitute a single data unit (transaction) under multiple users and environments. Indeed, they are not only independent, but also ensure the organic performance of the instruction units required in the current computing environment, where the additional instructions must be executed when a specific instruction is executed.

Description

Database transaction recovery with transaction completion key}

The present invention is directed to a method for ensuring consistent execution of a transaction consisting of a series of instructions by maintaining the integrity of the series of data without compromising the organic association of the instructions causing the series of data changes. The prior art eliminates the data change itself caused by the partial execution of a transaction when a transaction is made only partially due to a system error or other reason, which consists of a series of instructions to maintain only the integrity of the data. I'm using rollback. In the prior art, when the system is stopped and recovered due to an error or other reason, if all the commands in the transaction are executed based on the data recorded in the log storage 2 of FIG. 1, the data remains that the transaction is completed. If data is recovered and stored in permanent storage (Figure 2), but the transaction is incomplete, the data for that transaction is erased. In this method, however, the integrity of the data itself is maintained, but as a database management server, it cannot perform the task of completing the transaction execution received from the client. In this case, clients that are not obliged to check whether the transaction has been completed may determine that the transaction that has already been delivered to the server or a part of the transaction has been executed, resulting in inconsistency between the server and the client. Due to this client in the traditional narrow sense _- servers such problems in (Client / Server) environment appears frequently, global clients, such as the current World Wide Web (WWW) _- In a server environment in a single transaction that is sent to the server a number of Since various commands of users (clients) are included and it is virtually impossible for the server to arbitrarily control these clients unilaterally, inconsistency and legal problems in terms of transaction execution between user system and server system can be avoided. none.

The present invention is to solve the above problems when the server is interrupted transaction execution due to an error such as the system during the transaction operation or when the operation such as stopping and restoring the transaction execution for the purpose of transaction execution management After determining whether the transaction needs to be recovered, the transaction received from the user (client) as well as the data integrity (consideration) considered in the conventional method by recovering or canceling the remaining unsuccessful instructions of the transaction according to the determination. The goal is to guarantee the organic performance of the instructions within the service and ultimately the performance of the transaction itself.

In order to achieve this goal, the transaction execution key, which can be the basis for deciding whether to recover the remaining unexecuted part of the transaction according to the performance and the contents of the transaction, is introduced as part of the transaction. Based on this information by storing the information in permanent storage at the time of operation, if the system user recovers transactions after a system failure or for any operational reason, the remaining portions of the uncommitted transaction should be recovered or erased. By recovering or erasing the parts, it is characterized by the server to ensure the organic performance of the transaction considering the degree of execution of each command.

1 is a block diagram showing an existing method used by the database management server to maintain only data consistency in a transaction unit.

2 is a system configuration to which the present invention is applied

3 is a configuration diagram of a database transaction to which the present invention is applied.

Description of the main parts of the drawing

1: Temporary memory area of the database management server

2: Area where the database management server stores information about transaction processing

3: Permanent storage of database data

4: area for storing information about the transaction completion key that represents the baseline for the entire transaction

5: Key to distinguish transaction

6: Key that marks the beginning of a transaction

7: Perform transaction key

8: Key to end of transaction

Hereinafter, described in detail with reference to the accompanying drawings.

FIG. 2 is a diagram illustrating a configuration of a database management server having a transaction completion key information store. When a transaction including a transaction completion key is delivered, the server transfers the information to the transaction completion key information of FIG. Store in storage (4).

If the server is stopped during the transaction due to a system error or the like, the transaction completion key information store 4 of FIG. 2 is a permanent storage device and thus is not lost. When the server is restored again, the related art reads information related to transaction execution only from the log repository 2 shown in FIG. 1 or FIG. 2, but in the present invention, the structure of FIG. 3 is stored in the transaction completion key information store 4 Also read transaction information with.

The prior art recovers the entire data only when the transaction data completed in the information read from the log storage 2 of FIG. 1 or FIG. If reflected in the storage 3, and the transaction is not completed, all data changes due to the transaction are erased. However, in the method of the present invention, if the transaction must be completed by determining whether to complete or erase the rest, even in the case of an incomplete transaction, by using the information in the transaction completion key information store 4 of FIG. If it is determined that the transaction must be completed and canceled by performing an unexecuted portion, the transaction is canceled.

For this operation, the transaction completion key information structure of FIG. 2 is composed of the structure of FIG. 3. The detailed configuration and method used in the present invention are as follows.

As shown in FIG. 3, one transaction has a separator key 5 to distinguish transactions. This transaction has a key 6 representing the beginning of a transaction and a key 8 representing the end of the transaction, between which there is an instruction execution key corresponding to each instruction constituting the transaction, and a transaction completion key set at a specific position. Each command of the transaction is executed sequentially from the start position to the end position. When each command is executed, the execution status is indicated on the corresponding command execution key. When the database management server (DBMS) proceeds to the transaction completion key position of FIG. 3, the database management server (DBMS) displays the execution status on the transaction completion key. After that, even if the system is stopped due to a system error, such information is preserved because it is stored in permanent storage.

When the system is stopped and restored during the execution of such a transaction, the DBMS reads information having the structure of FIG. 3 from the transaction completion key information store 4 of FIG. If the execution status is not displayed in the transaction completion key 7 shown in FIG. 3 among the transactions that have not been completed (when the transaction could not be performed up to the transaction completion key position), all data changes caused by this transaction are erased (RollBack) )do. However, if the execution status is indicated in the transaction completion key in the transaction information (when a transaction is executed more than the transaction completion key position), the transaction is completed by executing the remaining instructions of the transaction that have not been executed yet. Through this process, the transaction completion key is used to indicate whether the transaction should be completed based on this information. Based on this information, the database management server can guarantee the organic performance based on the degree of command execution in the transaction and the performance of the transaction itself. It becomes possible.

As described above, the present invention enables the transaction to be recovered according to the degree of command execution in a transaction, so that in a client _- server distributed environment, if a specific command in a transaction is executed, the rest of the transaction must be performed. If necessary, set the transaction completion key to the position immediately after the command, so that when the command is executed, the transaction completion key at the next position is also displayed. Therefore, the entire transaction is executed according to whether or not the specific command specified by the client is executed. Control the performance of In addition, the database management server side guarantees the transaction performance considering the degree of execution of the transaction command execution unit while basically guaranteeing the data integrity of the transaction as in the prior art.

Through this, it is possible to avoid inconsistency of the transaction between the client and the server, transaction loss and the technical and legal problems that occur when the server unilaterally erases the commands in the transaction.

Claims (1)

Execution state set in this transaction completion key by storing transaction completion key information of the structure as shown in FIG. 3 in a permanent storage device such as a hard disk of a database shown in the transaction performance information store 4 of FIG. Commands that have completed the remaining unsuccessful execution of this transaction after determining that it is a transaction to be completed if the execution status is indicated by using the indication information, or to be erased if the execution status of this transaction completion key is not displayed. To cancel data changes and remaining commands