JP5224928B2 - Database consistency check device and method, program, and computer-readable recording medium - Google Patents

Description

  The present invention relates to a database consistency check apparatus, method and program, and a computer-readable recording medium, and more particularly to a database consistency check apparatus, method and program for checking the consistency of a database developed on a memory, and The present invention relates to a computer-readable recording medium.

  As a technology that can check consistency without stopping execution of database update transactions, starting from a block corresponding to a certain index, each data block is read in the order of relation, and the next data block is read. When the chain is interrupted, there is one that determines that at least one of the data blocks before and after the interrupted chain is the above (for example, see Patent Document 1).

However, if the database update and the consistency check are performed at the same time, the incomplete information database being updated is judged to be consistent in an inconsistent state (a state in which the originality is not maintained) during the update transaction process. And there is a possibility of misdiagnosis as inconsistent. Therefore, as shown in FIGS. 9A and 9B, either the database update or the consistency check acquires an exclusive lock, and performs processing within the exclusive section, whereby the database update and consistency are performed. Checks should not be made at the same time. To prevent such a database update and consistency check from being performed at the same time, a check lock is applied to restrict the access of other processes to the field or field combination being checked, and the field or field being checked is checked. There is a method of checking combination consistency (for example, see Patent Document 2).
JP-A-6-4588 JP-A-8-249222

  However, in the above technique, when the database update process and the consistency check conflict, as shown in FIGS. 9A and 9B, either the database update process or the consistency check is performed. However, when an exclusive lock is acquired, the remaining one needs to wait for acquisition of an exclusive lock, resulting in a delay in the response of the process.

  The present invention has been made in view of the above points, and a database consistency check apparatus and method capable of suppressing a delay in response time of a consistency check even when a database update process is performed. It is another object of the present invention to provide a program and a computer-readable recording medium.

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

The present invention (Claim 1) is a database consistency checking device for checking the consistency of a database,
A database 130 to be accessed and checked for consistency;
A lock resource management unit 110 that performs exclusive control so that other processes do not access the data in the database 130 while a process in the data in the database 130 is accessing;
When starting update processing and reference processing of data in the database 130, when an exclusive lock is requested to the lock resource management means 110 and notification that an exclusive lock is possible is made, the update processing or reference processing of the database is performed. Database processing means 100 to perform;
The consistency of the data in the database 130 is checked without making an exclusive lock request to the lock resource management means 110, and if it is determined that there is an inconsistency up to a preset number of times , the consistency of the database 130 is checked again. If there is inconsistency even if the preset number of times is reached, the lock resource management unit 110 is requested to obtain an exclusive lock, and when the exclusive lock is acquired, the check target section of the database 130 is cached. The exclusive lock release request is output to the lock resource management unit 110, the consistency in the cache is checked, and the consistency result is output. On the other hand, if the exclusive lock cannot be acquired, the exclusive lock is output. Database consistency checking means 120 for re-requesting the lock.

Further, the present invention (Claim 2 ) is provided in the lock resource management means 110.
In the case where the data section subject to exclusive control of the database competes between the database processing unit 100 and the database consistency checking unit 120, a unit that prioritizes the exclusive lock request that has been received first is included.

  FIG. 2 is a diagram for explaining the principle of the present invention.

The present invention (Claim 3) is a database consistency check method for checking the consistency of a database,
Lock resource management means for performing exclusive control so that other processes do not access the data in the database while a process in the data in the database of the access and consistency check is accessing ; and database processing means And a database consistency check means ,
When the database processing means acquires an exclusive lock from the lock resource management means, a database processing step for performing update processing or reference processing of the database; and
The database consistency check means checks the consistency of data in the database without making an exclusive lock request to the lock resource management means (step 1), and determines that there is inconsistency up to a preset number of times. If yes (Step 2, Yes), the database consistency is checked again (Step 1 ). If there is inconsistency even if the preset number of times is reached (Step 2, Yes, Step 3, Yes) When an exclusive lock is requested to the lock resource management means and the exclusive lock is acquired (step 4, OK ), the check target section of the database is copied to the cache ( step 5 ), and the exclusive lock release request is transferred to the lock. output to the resource management unit (step 6), checks the integrity of the cache (step 7,8), and outputs the matching result (scan Step 9 ) On the other hand, if the exclusive lock could not be acquired ( step 4, NG ), a database consistency check step for re-requesting the exclusive lock is performed.

Further, the present invention (Claim 4 ) is provided in the lock resource management means.
When the data section subject to exclusive control of the database competes between the database processing step and the database consistency check step , the exclusive lock request that has been received first is given priority.

The present invention (Claim 5 ) is a database consistency check program for causing a computer to function as each means constituting the database consistency check apparatus according to Claim 1 or 2 .

The present invention (Claim 6 ) is a computer-readable recording medium in which the database consistency check program according to claim 5 is stored.

  As described above, according to the present invention, by executing the initial consistency check of the database without acquiring the exclusive lock, the consistency check itself and the database update processing can be performed by acquiring the exclusive lock. It is possible to run at the same time without failure. Thereby, even if it is a case where the update of a database is performed, the delay of the response time of a consistency check can be suppressed. Further, even when the consistency check is being performed, the delay of the database update process can be suppressed.

  In addition, if the initial consistency fails, the possibility of misjudgment as inconsistency is reduced by retrying, and a delay in the response time of the database update process can be suppressed.

  Further, by acquiring the exclusive lock, copying to the cache, releasing the exclusive lock, and performing the consistency check, it is possible to shorten the exclusive lock period and suppress the delay in the response time of the database.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 3 is a configuration diagram of the database consistency check device according to the first embodiment of the present invention.

  The database consistency check apparatus shown in FIG. 1 includes a database processing unit 100, a lock resource management unit 110, a consistency check unit 120, and a database 130.

  The database processing unit 100 performs update processing and reference processing of the database 130. When performing update processing, an exclusive lock is acquired from the lock resource management unit 110.

  The lock resource management unit 110 has an index and data update lock table 115 for each index in the database 130 in a memory (not shown). When an exclusive lock request including an index of data in the database 130 is acquired from the database processing unit 100 or the consistency check unit 120, by referring to the table 115 based on the index, data that is not currently in an exclusive lock is obtained. An exclusive lock is permitted, a flag indicating the exclusive lock is set in the table 115 (turned ON), and exclusive control is performed on the data. When the exclusive lock is released, the flag in the table 115 is set to OFF, and the exclusive control is released. The lock resource management unit 110 permits the exclusive lock to the database processing unit 100 and the consistency check unit 120 when the flag of the data section subject to the consistency check in the update lock table 115 is “OFF”. "Is returned, and if the flag is" ON "," NG "that does not permit exclusive lock is returned. Further, when an exclusive lock acquisition request is received from both the database processing unit 100 and the consistency check 120, the exclusive lock is preferentially granted to the one that has received the request first.

  The consistency check unit 120 first performs a consistency check without performing an exclusive lock, and when it is diagnosed as inconsistent, requests an exclusive lock from the lock resource management unit 110 and acquires an exclusive lock. . The consistency check unit 120 uses a database control table check, an index / database correlation check, a database data structure check, and the like for the consistency check.

  The operation in the above configuration will be described below.

  First, the operation of the database processing unit 110 will be described.

  FIG. 4 is a flowchart of database processing according to the first embodiment of this invention.

  When the database processing unit 100 starts database processing, the database processing unit 100 acquires an exclusive lock from the lock resource management unit 110 (step 101), and when successful (when OK is acquired from the lock resource management unit 110), the index of the database 130 is acquired. Then, the row is updated (step 102), and when the update process is completed, an exclusive lock release release request is output to the lock resource management unit 110 (step 103), and the process ends.

  Next, the operation of the consistency check unit 120 will be described.

  The feature of the operation described below is that the exclusive lock is not acquired and the processing time is shortened in the initial check process of the consistency of the database 130.

  FIG. 5 is a flowchart (part 1) of the database consistency check according to the first embodiment of this invention.

  When the consistency check is started in the database consistency check unit 120, the consistency check is performed without acquiring an exclusive lock for the first time (step 201), it is determined whether there is inconsistency, and it is determined that there is no inconsistency. In this case (step 202, none), the determination result of “no inconsistency” is output (step 208), and the process is terminated. On the other hand, if it is diagnosed as “inconsistent”, an exclusive lock request is made to the lock resource management unit 110, and if successful (step 203, OK), a consistency check is performed (step 204). An exclusive lock release request is issued to the lock resource management unit 110 (step 205). If the exclusive lock fails (step 203, NG), an exclusive lock request is made again (step 203). It is determined whether or not the result of the consistency check is inconsistent. If there is an inconsistency (Yes in Step 206), the determination result of “inconsistent” is output, and the process ends (Step 207). If there is no inconsistency (step 206, none), “no inconsistency” is output as a determination, and the process ends (step 208).

  When the exclusive section of the database processing (steps 102 to 104) in FIG. 4 and the exclusive section of the database consistency check process (steps 203 to 205) conflict with each other, the lock resource management unit 110 controls whichever The process that acquired the exclusive lock is executed.

  The initial consistency check (step 201) of the consistency check process can be executed even in the exclusive section (steps 102 to 104) of the database process.

  FIG. 6 is a diagram for explaining the database consistency check according to the first embodiment of this invention.

  With the above processing, as shown in FIG. 6A, since the consistency check is executed without acquiring the exclusive lock at the beginning, neither the consistency check itself nor the database update process fails to acquire the exclusive lock. Can be executed simultaneously. At this time, there is a possibility of misdiagnosis as inconsistent. However, by acquiring the exclusive lock again and performing the consistency determination again in a state where the database update processing is not performed simultaneously (FIG. 6B )), It can be judged whether the initial diagnosis was a misdiagnosis or whether the diagnosis was correct and inconsistent.

  The probability of inconsistency due to misdiagnosis is at least simultaneous or low because the processing sections misdiagnosed as inconsistent by the consistency check among the time sections in which update processing is performed are the same or short. In general, since processing that is not determined to be inconsistent, such as transaction processing, is included, the probability of inconsistency due to misdiagnosis is low. As a result, a delay in response time of the update process of the database 130 or the consistency check is suppressed.

[Second Embodiment]
In the present embodiment, an additional process when it is determined that “there is inconsistency” in the initial consistency check (step 201) in FIG. 5 described above (step 202 is present) will be described.

  FIG. 7 is a flowchart of database consistency check according to the second embodiment of this invention. In the figure, the same operations as those in FIG. 5 are denoted by the same step numbers, and the description thereof is omitted. The apparatus configuration is the same as that shown in FIG.

  Before performing the process of step 201 in FIG. 5, the initial value of the retry counter i is set (i = 0). If it is determined in step 202 that “there is inconsistency”, a predetermined retry is performed. It is determined whether or not the number of trials has been exceeded. If the number has been exceeded (Yes at Step 302), the process proceeds to Step 203. If not exceeded (No at step 302), 1 is added to the counter i of the number of retries (i = i + 1), and the process proceeds to step 201 (step 303).

As a result, even if the first consistency check (step 201) becomes inconsistent, the probability of misdiagnosis is less than 1 by performing retry until the number of retries exceeds the predetermined number of retries. Then, since p ⁽ⁿ⁾ > p ^{(n + 1),} it is possible to reduce the probability of misdiagnosis without acquiring an exclusive lock by repeating the above processing. As a result, exclusive lock can be suppressed.

[Third Embodiment]
In the present embodiment, a case will be described in which copying is performed to the cache without performing the consistency check in step 204 of FIG. 5 in the first embodiment.

  FIG. 8 is a flowchart of database consistency check according to the third embodiment of the present invention. In the figure, the same operations as those in FIG. 5 are denoted by the same step numbers, and the description thereof is omitted. The apparatus configuration is the same as that shown in FIG.

  After acquiring the exclusive lock (step 203, OK), without checking the consistency, copy to the cache in the check section (step 401), release the exclusive lock (step 204), and check the consistency in the cache (Step 402) and it is determined whether there is consistency (step 206).

  As a result, the exclusive lock is acquired, copied to the cache, then the exclusive lock is released, the consistency check is performed outside the exclusive lock section (in the cache), and the consistency check is performed. When the cache copy time is shorter than the above check, the exclusive lock period is shortened, and the delay of the response time of the database 130 can be suppressed.

  For each component of the database consistency check device shown in FIG. 3, the operations shown in the first to third embodiments are constructed as a program and installed in a computer used as the database consistency check device. Or can be distributed via a network.

  Further, the constructed program can be stored in a portable storage medium such as a hard disk, a flexible disk, or a CD-ROM, and can be installed or distributed in a computer.

  The present invention is not limited to the above-described embodiments and examples, and various modifications and applications can be made within the scope of the claims.

  The present invention is applicable to a database consistency check technique.

It is a principle block diagram of this invention. It is a figure for demonstrating the principle of this invention. It is a block diagram of the database consistency check in the 1st Embodiment of this invention. It is a flowchart of the database process in the 1st Embodiment of this invention. It is a flowchart of the database consistency check in the 1st Embodiment of this invention. It is explanatory drawing of the database consistency check in the 1st Embodiment of this invention. It is a flowchart of the database consistency check in the 2nd Embodiment of this invention. It is a flowchart of the database consistency check in the 3rd Embodiment of this invention. It is a figure which shows the conventional database consistency check method.

Explanation of symbols

100 Database processing unit, database processing unit 110 Lock resource management unit, lock resource management unit 115 Update lock table 120 Database consistency check unit, consistency check unit 130 Database

Claims (6)

A database consistency check device for checking database consistency,
A database subject to access and consistency checks; and
Lock resource management means for performing exclusive control so that other processes do not access the data in the database while a process in the data in the database is accessing;
When starting update processing and reference processing of the data in the database, if an exclusive lock is requested to the lock resource management means and it is notified that the exclusive lock is possible, the update processing or reference processing of the database is performed. Database processing means to perform;
Without making an exclusive lock request to the lock resource management means, the consistency of the data in the database is checked, and if it is determined that there is inconsistency up to a preset number of times, the consistency of the database is again performed. If there is inconsistency even if the preset number of times is reached, the lock resource management means requests the exclusive lock, and when the exclusive lock is acquired, the check target section of the database is cached. The exclusive lock release request is output to the lock resource management means, the consistency in the cache is checked, and the consistency result is output. On the other hand, if the exclusive lock cannot be acquired, the exclusive lock Database integrity check means to re-request
A database consistency checking device comprising: The lock resource management means includes
2. A means for giving priority to an exclusive lock request received earlier when a data section subject to exclusive control of the database conflicts between the database processing means and the database consistency check means. The database consistency check device described. A database integrity check method for checking the integrity of a database,
Lock resource management means for performing exclusive control so that other processes do not access the data in the database while a process in the data in the database of the access and consistency check is accessing ; and database processing means And a database consistency check means ,
When the database processing means acquires an exclusive lock from the lock resource management means, a database processing step for performing update processing or reference processing of the database;
The database consistency check means checks the consistency of data in the database without making an exclusive lock request to the lock resource management means, and determines that there is inconsistency up to a preset number of times. If the consistency of the database is checked again and there is inconsistency even if the preset number of times is reached, an exclusive lock is requested to the lock resource management means, and an exclusive lock is acquired. The check target section of the database is copied to the cache, the exclusive lock release request is output to the lock resource management means, the consistency in the cache is checked, the consistency result is output, and the exclusive lock is acquired. If not, a database integrity check step that re-requests an exclusive lock;
A database consistency check method characterized by: In the lock resource management means,
4. The database according to claim 3, wherein when a data section subject to exclusive control of the database competes between the database processing step and the database consistency check step, the exclusive lock request received earlier is given priority. Consistency check method.   A database consistency check program for causing a computer to function as each means constituting the database consistency check device according to claim 1.   A computer-readable recording medium storing the database consistency check program according to claim 5.

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