JPH07101399B2 - Database deadlock processing method - Google Patents

Description

The present invention relates to a deadlock processing method in a database system adopting a delay change method.

[Conventional technology]

In some database systems, to maintain integrity and performance against deadlocks and other failures,
A so-called delay change method is adopted. Here, the delayed change method means that even if a change is made to the database, the update result is not written to the database and is held in the primary file such as a journal file until the processing is completed, and the contents of the primary file are updated at an appropriate timing. Are collectively written in the database. Reflecting the contents of the primary file in the database in this way is called establishment of a stationary point. According to this method, when a deadlock or the like occurs, the contents of the primary file can be simply discarded, and the state of the previous quiesce point, which is confirmed to be normal, can be easily restored. There are advantages.

By the way, conventionally, a command for executing the above-mentioned processing for establishing a stationary point (stationary point establishing processing) and a command for performing recovery processing (recovery processing) when a deadlock or the like occurs are executed by a user program. And, as part of the function of the user program, they were also programming at the same time.

[Problems to be Solved by the Invention]

As described above, the conventional database system is sufficiently effective because all the processing is not wasted even if a deadlock or the like occurs, and it is sufficient to go back to the previous quiesce point. As the program logic of the user program, a program for issuing a command for stationary point establishment processing and recovery processing, which is not originally required, has to be constructed, so that there is a drawback that programming becomes complicated.

Also, the conventional database system can only recover a database that has primary files such as journal files, and recovery of memory, report files, sequential files without journals, etc. is not possible by a recovery processing command to the database system. Met. Therefore, in order to recover these, the user program must save their contents in advance and create a complicated processing function to perform recovery after a deadlock occurs. There was a drawback that it became more difficult.

The present invention has been proposed in view of the above points, and it is an object of the present invention that a user program need not be aware of measures such as deadlocks at all, and a memory, a report file, and a journalless sequential file. It is to provide a database deadlock processing method that can similarly perform recovery for the above.

[Means for Solving the Problems]

In order to achieve the above object, the present invention embeds an execution program monitor calling means embedding means provided in a compiler into an input transaction file input step in an object program in a deadlock processing method in a database system adopting a delayed update method. Executed program monitor calling means and the executed program monitor calling means at the time of executing the object program, and determines the necessity of establishing a quiesce point based on the buffer lock list amount and the journal file remaining amount, and determines that it is necessary. Database quiesce point automatic establishment means for requesting the database quiesce point establishment processing to the database monitor at the same time, and memory, report file, journalless sequential organization simultaneously with the quiesce point establishment processing While evacuating the contents of the file such as the evacuation area, it is called by the execution program monitor call unit to deadlock the event, carries out a request for rollback of the database to the database monitor, memory, report file,
A recovery means for recovering the contents of the journalless sequential file and the like based on the contents of the save area is provided.

[Action]

In the database deadlock processing method of the present invention, the execution program monitor calling means embedded in the input transaction file input step in the object program by the execution program monitor calling means embedding means provided in the compiler is the object program. The database quiesce point automatic establishment means of the execution program monitor is called at the time of execution, and the called database quiesce point automatic establishment means judges the necessity of establishing the quiesce point based on the buffer lock list amount and the journal file remaining amount, and When the determination is made, a request for establishing the quiesce point of the database is issued to the database monitor, and at the same time as the quiesce point establishing process, the recovery means of the program monitor executes the memory, the report file, and the journalless sequential organization file. Retracting the contents such as Le to the save area. Also, when a deadlock occurs, the execution program monitor calling means calls the recovery means again, requests the database monitor to roll back the database, and saves the contents of the memory, the report file, the journalless sequential organization file, etc. Restore based on the contents of the area.

〔Example〕

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

FIG. 1 is a block diagram showing an embodiment of a database system to which the database deadlock processing method of the present invention is applied. In FIG. 1, this embodiment is a database.
16, a memory (not shown), a report file 14, a journalless sequential file 15 and the like are used in the process of execution, a source program 1 is input, and a compiler 2 that outputs an object program 4 and an object The program 4 includes an execution program monitor 8 that monitors and controls processing when executing the program 4, a save area 7 used by the execution program monitor 8, and a database monitor 13 that monitors and controls processing related to the database 16. The journal file 17 is a primary file that holds the update result after the quiesce point for the database 16 in order to execute the delayed update.

On the other hand, as a feature of the present invention, the compiler 2 executes the execution program monitor calling means embedding means 3, and the object program 4 executes the execution program monitor calling means 6 in addition to the object program body 5 corresponding to the source program 1. The program monitor 8 has a journalless sequential file automatic rollback means 9 and a report file automatic rollback means which constitute recovery means.
10, memory automatic save / restore means 11 and database quiesce point automatic establishing means 12 are respectively provided. In addition,
The function of each means is as follows.

Execution program monitor calling means Embedding means 3; Source program 1 is compiled to obtain object program 4
A function of embedding the execution program monitor calling means 6 in the object program 4 when generating the.

Execution program monitor calling means 6; When the object program 4 is executed, the database quiesce point automatic establishing means 12 of the execution program monitor 8 is properly called for quiesce point establishing processing, and when a deadlock occurs, the journal-less sequential organization of the execution program monitor 8 is executed. A function for calling recovery means including a file automatic rollback means 9, a report file automatic rollback means 10, and a memory automatic save / recovery means 11 for recovery processing.

Database quiesce point automatic establishment means 12; Execution program monitor calling means 6 when the object program 4 is executed
When called by, the necessity of establishing a quiesce point is determined by the buffer lock list amount (the amount of the buffer list indicating the lock status for each buffer in the database 16) and the journal file remaining amount (remaining amount of the journal file 17). A function of requesting the stationary point establishment process to the database monitor 13 if necessary.

Journalless sequential file automatic rollback means 9;
At the same time as the quiesce point establishing process of the database quiesce point automatic establishing means 12 is performed, the contents of the journalless sequential file 15 (file position indicator) is saved in the save area 7, and the execution program monitor calling means 6 is executed when a deadlock occurs.
Journalless sequential files when called by
Function to restore the contents of 15 based on the contents of the evacuation area 7.

Report file automatic rollback means 10; Restoration point establishment processing of the database quiesce point automatic establishment means 12 and the contents of the simultaneous report file 14 (file position indicator) are saved in the save area 7, and the execution program monitor is called when deadlock occurs. A function to restore the contents of the report file 14 based on the contents of the save area 7 when called by the means 6.

Memory automatic save / restore means 11; When the contents of the memory are saved in the save area 7 at the same time as the static point establishment processing of the database static point automatic establishing means 12, and when called by the execution program monitor calling means 6 when a deadlock occurs, A function to restore the contents of the memory based on the contents of the save area 7.

Next, the operation of the above embodiment will be described.

First, when the compiler 2 generates the object program 4 from the input source program 1, the compiler 2 executes the source program 1 in the object program 4 in addition to the coded object body 5 by the execution program monitor calling means embedding means 3. The program monitor calling means 6 is embedded.

FIG. 2 shows an example of the object body 5 of the object program 4, and the operation at the time of execution of the object program 4 will be described below with reference to FIGS. 1 and 2. This user program takes the input transaction file 18 as an input, and if necessary, the database 16 (journal file 17) which is a master file.
Is an example of a program that updates the output and outputs the output form 19 to the journalless sequential file 15 as an output transaction file, and also outputs the output form 19 via the report file 14.

When the execution is started, after the initial processing (step 51), every time the input file is read (step 52), the execution program monitor calling means 6 calls the database stationary point automatic establishing means 12 of the execution program monitor 8. To be done. The called database quiesce point automatic establishing means 12 judges the necessity of establishing the quiesce point based on the buffer lock list amount and the journal file remaining amount, and if necessary, requests the database monitor 13 for the quiesce point establishing process. That is, the buffer lock list amount is
16 It is a measure of the access status. On the other hand, when the remaining amount of the journal file becomes small, there is a possibility of overflow, so it is necessary to establish a quiesce point as soon as possible. This makes it possible to determine the necessity of establishing a stationary point at the present time. Further, when the stationary point establishing process is performed, at the same time, the journalless sequential file automatic rollback means 9, the report file automatic rollback means 10, and the memory automatic save / recovery means 11 of the execution program monitor 8 respectively journal. The contents of the none sequential file 15, the report file 14, and the memory are saved in the save area 7, and a quiescent point is established for these as well.

Then, after the stationary point establishing process is completed, or when it is determined that the stationary point establishing process is not required, the process proceeds to the next step without performing any particular process, and the corresponding transaction process (steps 54, ..., 55) To execute. If it is determined in step 53 that the input has been completed, the process proceeds to step 56 and the end process is performed.

If a deadlock occurs when the database 16 is updated in the transaction process of step 54 and an update request is issued to the database 16 in the subsequent transaction process of step 55, the execution program monitor calling means 6 is executed. The execution program monitor 8 is called by and the database 16 is the database monitor.
13 is rolled back, the journalless sequential file 15 is rolled back by the journalless sequential file automatic rollback means 9 based on the contents of the save area 7, and the report file 14 is saved by the report file automatic rollback means 10. The memory is rolled back based on the contents of the area 7, and the memory is restored by the automatic memory saving / recovering means 11 based on the contents of the saving area 7.

With these processes, the database system is step 52.
By returning to the previous state and starting the process again,
Processing can continue as if a deadlock did not occur.

〔The invention's effect〕

As described above, in the database deadlock processing method of the present invention, the execution program monitor calling means embedded in the input transaction file input step in the object program by the execution program monitor calling means embedding means of the compiler is The database quiesce point automatic establishment means is called in the input transaction file input step during execution of the object program, and the database quiesce point automatic establishment means judges the necessity of establishment of the quiesce point based on the buffer lock list amount and the journal file remaining amount, When it is determined that it is necessary, the database monitor is requested to establish the stationary point of the database. As a result, the quiesce point establishing process is performed, and at the same time, the recovery means saves the contents of the memory, the report file, the journalless sequential file, and the like in the save area. When the recovery means is called when a deadlock occurs, a database rollback request is issued to the database monitor and the contents of memory, report file, journalless sequential file, etc. are restored based on the contents of the save area. To do. Therefore, the user program (source program) does not need to be aware of the processing for deadlock or the like at all, and there is an effect that programming becomes very easy.

Also, memory, report files, journal-less sequential files, etc., which could not be recovered by the conventional database system, can be recovered in the same way as the database, so even if the user program does not perform complicated processing There is an effect that the processing state at the point can be reproduced.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a database system to which the database deadlock processing method of the present invention is applied, and FIG. 2 is an operation explanatory diagram thereof. In the figure, 1 ... Source program 2 ... Compiler 3 ... Execution program monitor calling means Embedding means 4 ... Object program 5 ... Object body 6 ... Execution program monitor calling means 7 ... Save area 8 ... Execution program Monitor 9 …… Sequential file without journal Automatic rollback means 10 …… Report file automatic rollback means 11 …… Memory automatic save / recovery means 12 …… Database static point automatic establishment means 13 …… Database monitor 14 …… Report file 15 …… Sequential file without journal 16 …… Database 17 …… Journal file 18 …… Input transaction file 19 …… Output form

Claims (1)

[Claims] 1. A deadlock processing method in a database system adopting a delayed update method, wherein an execution program monitor calling means embedded in a compiler is used to execute an execution program monitor call embedded in an input transaction file input step in an object program. And a means for calling the execution program monitor calling means at the time of executing the object program, determining the necessity of establishing a quiesce point based on the buffer lock list amount and the journal file remaining amount, and quiescing the database when it is determined to be necessary. Database quiesce point automatic establishment means for making a request for point establishment processing to the database monitor, and at the same time with the quiesce point establishment processing, the contents of memory, report file, journalless sequential organization file, etc. are saved. The contents are saved to the rear and called by the execution program monitor calling means when a deadlock occurs, requesting rollback of the database to the database monitor, and contents of memory, report file, journalless sequential file, etc. A deadlock processing method for a database, comprising: a recovery means for recovering the data based on the contents of the save area.