WO2011009274A1

WO2011009274A1 - Method and apparatus of concurrency control

Info

Publication number: WO2011009274A1
Application number: PCT/CN2009/076082
Authority: WO
Inventors: 印和平; 常二鹏; 卢勤元; 丁奇鹏; 陈河堆
Original assignee: 中兴通讯股份有限公司
Priority date: 2009-07-23
Filing date: 2009-12-25
Publication date: 2011-01-27
Also published as: CN101615203A; CN101615203B

Abstract

A method of concurrency control includes the following steps: first, judging, according to a lock relation list, whether the position at which a transaction is waiting to be performed has a lock conflicting with a lock waiting to be allotted, said lock relation list being used to store the relations between transactions and locks; second, allotting a lock to the transaction according to the judgment and performing the transaction; third, when the transaction is complete, releasing the lock held by the transaction, and allotting any locks of all released locks which do not need to continue waiting to other concurrency transactions. Also provided is a concurrency control apparatus which includes: a judging module; a performing module; a releasing module.

Description

Concurrent control method and device

The present invention relates to the field of databases, and in particular to a concurrency control method and apparatus. Background technique

A database is a shared resource. In a database system, there may be multiple concurrently executed transactions at the same time. When multiple users access the database concurrently, multiple transactions will access the same database at the same time. This leads to various conflicts. For example, the transactions T1 and Τ2 may have the following three types of conflicts during concurrent execution:

1) Write-read (WR) conflict, that is, T2 reads data that has just been modified by T1 and has not yet been committed, so that T2 reads dirty data, also called "dirty read";

2) Read-Write (RW) conflict, that is, T2 modifies the data just read by T1 and T1 has not yet ended, so if T1 reads the same object again, its value will change, also called

"Cannot read repeatedly";

3) Write-Write (WW) conflict, that is, T2 overwrites the value that has just been modified by T1 and T1 has not yet ended, which will result in inconsistent data.

Serial scheduling guarantees data consistency, but it is not conducive to system performance. Therefore, the Database Management System (DBMS) must provide transaction concurrency control mechanisms. Serializable is the criterion for the correctness of concurrent transactions, so a given concurrency control is properly controlled if and only if it is serializable.

Strict 2-Phase Locking (Strict 2PL) protocol guarantees the serializability of concurrency control. Its contents are as follows: 1) Read/write lock must be added before reading/writing database objects; 2) Transaction After execution (commit or rollback), release the lock it owns.

A concurrency control method is provided in the related art, which is performed on a database that is operated Record locks and queue other concurrent transactions to prevent the record from being modified by other transactions at the same time.

However, the concurrency control method in the related art causes all concurrent transactions requesting operations on the same database record to enter the waiting queue until the lock operation is released after the lock transaction execution ends, and other concurrent transactions can be operated on the database again. The concurrency of transaction control is low, and concurrency control is poor. Summary of the invention

The present invention is directed to a concurrency control method and apparatus, which can solve the concurrency control method in the related art, so that all concurrent transactions requesting operations on the same database record enter the waiting queue until the lock transaction is terminated, and the lock is released. After that, other concurrent transactions can be operated on the database again, resulting in low concurrency of transaction control and poor system performance.

In an embodiment of the present invention, a concurrency control method is provided, including the following steps: determining, according to a lock relationship table, whether a to-be-operated location of a transaction has a lock that conflicts with a lock to be granted, and the lock relationship table is used to save a transaction and a lock. The relationship; grants a lock to the transaction based on the result of the judgment, and executes the transaction; when the execution of the transaction ends, the lock held by the transaction is released, and the lock of the released lock that does not need to continue waiting is granted to other concurrent transactions.

Preferably, in the concurrency control method, the lock relationship table specifically includes: a transaction list for storing concurrently executed and uncommitted transactions; a lock hash table for tracking queued waiting locks; and a linked list for associating transactions With a lock.

Preferably, in the concurrency control method, the lock is granted to the transaction according to the judgment result, and executing the transaction specifically includes: if the to-be-operated position of the transaction has no lock, grant the lock to the transaction, and execute the transaction.

Preferably, in the concurrency control method, the lock is granted to the transaction according to the judgment result, and the executing the transaction specifically includes: if there is a lock in the to-be-operated position of the transaction, checking whether there is a conflict between the existing lock and the lock to be granted; The transaction grants a lock and executes the transaction.

Preferably, in the above concurrency control method, a lock is granted to the transaction according to the check result, and The line transaction specifically includes: If there is no conflict between the existing lock and the pending lock, the lock is granted to the transaction, and the transaction is executed.

Preferably, in the concurrency control method, the lock is granted to the transaction according to the check result, and executing the transaction specifically includes: if the existing lock conflicts with the pending latch, setting the transaction queue waiting until the lock is to be re-acquired; executing the transaction.

Preferably, in the concurrency control method described above, the executing transaction includes at least one of the following: performing an adding operation, performing a deleting operation, performing a modifying operation, and performing a reading operation.

Preferably, in the above concurrency control method, the end of the transaction execution includes: a transaction completion submission or a transaction completion rollback.

Preferably, in the above concurrency control method, granting the lock that does not need to continue waiting in the released lock to the other concurrent transaction specifically includes: detecting, for each lock in the linked list of the released lock, whether there is a waiting flag; when there is a waiting flag And when the detected lock does not have a lock type conflict with other locks at the same operation position of other concurrent transactions, the detected lock is granted to other concurrent transactions, and other concurrent transactions are resumed. The lock types include shared locks and exclusive locks. .

In an embodiment of the present invention, a concurrency control device is further provided, including: a judging module, configured to determine, according to the lock relationship table, whether a to-be-operated position of the transaction has a lock that conflicts with the lock to be granted, and the lock relationship table is used. The relationship between the transaction and the lock is saved; the execution module is configured to grant a lock to the transaction according to the judgment result, and execute the transaction; and release the module, when the transaction execution ends, release the lock held by the transaction, and the released lock does not need to continue The waiting lock is granted to other concurrent transactions.

Preferably, in the concurrency control device, the lock relationship table specifically includes: a transaction list for storing concurrently executed and uncommitted transactions; a lock hash table for tracking the queued waiting lock; a linked list for the associated transaction With a lock.

In the above embodiment, since the relationship between the transaction and its corresponding lock is saved by using the lock relationship table, it is possible to judge whether there is a conflict between different locks pointing to the same to-be-operated position, and perform differential processing according to the judgment result, instead of concurrently as in the related art. Like the control method, once the position to be operated When there is a lock, all the transactions corresponding to other locks are included in the waiting queue, so the concurrency of the concurrency control method in the related art is low, the system performance is poor, and the concurrency of the transaction control is improved. , improved concurrency control effects. DRAWINGS

1 is a flow chart showing a concurrency control method according to a first embodiment of the present invention; FIG. 2 is a view showing a lock hash table used in the concurrency control method of FIG.

3 is a flow chart showing a concurrency control method according to a second embodiment of the present invention; and FIG. 4 is a block diagram showing a concurrency control device according to a third embodiment of the present invention. detailed description

The invention will be described in detail below with reference to the drawings in conjunction with the embodiments.

1 shows a flow chart of a concurrency control method according to a first embodiment of the present invention, the method comprising the following steps:

Step S101, when the database is operated, determining, according to the lock relationship table, whether the to-be-operated position of the transaction has a lock that conflicts with the lock to be granted, and the lock relationship table is configured to save the relationship between the transaction and the lock; Step S102, according to the judgment result, the transaction Grant a lock, and execute a transaction;

Step S103, when the execution of the transaction ends, the lock held by the transaction is released, and the lock of the released lock that does not need to continue to wait is granted to other concurrent transactions.

In this embodiment, first, according to the lock relationship table, it is determined whether the to-be-operated position of the transaction has a lock that conflicts with the lock to be granted, and then the lock is granted to the transaction according to the judgment result, and the transaction is executed, and finally, when the execution of the transaction ends, the transaction is held. Lock, and grant the lock that does not need to wait for the released lock to other concurrent transactions. Since the lock relationship table is used to save the relationship between the transaction and its corresponding lock, it is possible to judge whether there is a conflict between different locks pointing to the same to-be-operated position. And distinguishing according to the judgment result, instead of including the transaction corresponding to all other locks in the waiting queue once the position to be operated is locked, as in the concurrency control method in the related art, thus overcoming the related art The concurrency control method has low concurrency for transaction control and poor system performance, which improves the concurrency of transaction control and improves the concurrency control effect.

The lock relationship table in this embodiment specifically includes a transaction list, a lock hash table, and a lock list. The setting of the above table enables the concurrency control method of the embodiment to effectively manage transactions and locks, including fast index positioning and traversal search. And so on, further determining whether there is a conflict in different locks pointing to the same to-be-operated position, and providing strong support for the above-mentioned concurrency control method.

The transaction list holds transaction information of other transactions executed concurrently in the system at the time of execution of the current transaction, and is inserted according to the principle that the latecomer inserts into the queue. The transaction information includes the transaction ID, the transaction type, the pointer to the front and rear nodes in the transaction list, and the chain. Table header pointers, etc. Each time a transaction is started, the transaction is inserted into the transaction list, and the transaction information for that transaction is saved to the transaction list. The transaction structure contains a thread structure information, which contains the event object. When the transaction is suspended due to waiting for the lock, the thread executing the transaction waits for the event object. When the transaction grants the lock and is awakened, the thread that granted the lock sets the event object. .

2 is a schematic diagram of a lock hash table used in the concurrency control method of FIG. 1. As shown in FIG. 2, each entry of the lock hash table corresponds to a header of a linked list, so that the lock is made The file space number and page number recorded in the structure are calculated by the key, and the corresponding lock list can be located through the corresponding lock hash table entry.

The linked list is used to associate the records recorded in the transaction list with the locks recorded in the lock hash table. As shown in Figure 2, each linked list includes multiple lock structures, and each lock structure records the database of lock locks waiting in line. Recorded file space number, page number, lock bitmap, number of bits occupied by the lock bitmap, lock type (shared lock, exclusive lock), lock flag (waiting, grant), belonging transaction, etc., The first heap_no bit of the lock bitmap is the identifier of the location record to be operated. Each transaction corresponds to one The linked list, each transaction is applied to a lock list, and the lock list holds the lock held by the transaction. Each pair of records operates, and the corresponding lock is inserted into the corresponding transaction. In the list of chains. A lock structure can be shared by other locks of the same type on the same page. If you need to add the same type of lock to other records, you only need to find the lock in the linked list. If you find it, you will lock the corresponding heap_no of the bitmap. The position bit, which solves the hash conflict by using a single linked list, and effectively saves memory space.

Preferably, in the above concurrency control method, step S102 specifically includes: if the to-be-operated position of the transaction has no lock, grant a lock to the transaction, and execute the transaction.

In this embodiment, if there is no lock in the to-be-operated position of the transaction, the lock is granted to the transaction, and the corresponding transaction is executed. In this way, the database record to be operated accepts the operation of the transaction when there is no other transaction, and the concurrent control is guaranteed. Under the premise of correctness, the concurrency of control is improved.

Preferably, in the above concurrency control method, step S102 specifically includes: if there is a lock in the to-be-operated position of the transaction, checking whether there is a conflict between the existing lock and the lock to be granted; granting a lock to the transaction according to the check result, and executing the transaction.

In this embodiment, if there is a lock in the to-be-operated position of the transaction, it is necessary to continue to check whether there is a conflict between the existing lock and the lock to be granted. The conflict includes: WR conflict, RW conflict, and WW highlight, and then grant the transaction according to the check result. Lock, and execute the transaction, in this way, the difference between the conflicting and non-existing conflicts can be handled differently, instead of waiting for the existing locks, all other transactions are suspended and waiting for the control to improve the concurrency of the control. .

Preferably, in the concurrency control method, the lock is granted to the transaction according to the check result, and executing the transaction specifically includes: if the existing lock does not conflict with the lock to be granted, grant the lock to the transaction, and execute the transaction.

In this embodiment, although the pending location of the transaction has a lock, the result of the check is that there is no conflict between the existing lock and the lock to be granted. At this time, the lock is still granted to the transaction, and the transaction is executed. This embodiment grasps the execution timing of concurrent transactions without affecting each other, so that the available resources are maximized. The concurrency of control is effectively improved than the concurrency control method in the related art.

In this embodiment, if the to-be-operated position of the transaction has a lock, and the existing lock conflicts with the pending latch, the transaction is set to hang, and the insertion wait queue is queued until the lock to be granted is regained, and the transaction is executed. Do, so that the transaction must satisfy the existing lock at the position to be operated and the existing lock and the pending lock are in conflict condition, then the wait is pending, that is, the transaction waits only when it is determined that it will be affected by other concurrent transactions. Under the premise of correctness of control, the concurrency of control is improved.

Preferably, in the concurrency control method described above, the executing transaction includes at least one of: performing an insert (also called an insert) operation, performing a delete operation, performing a modify operation, and performing a read operation.

Execution transactions in this embodiment may be additions, deletions, modifications, reads, or a combination thereof. The concurrency control method of this embodiment is not limited to a certain operation, but can be extended to the above four basic operations, or a combination thereof, to expand the application range.

FIG. 3 is a flowchart of a concurrency control method according to a second embodiment of the present invention. In this embodiment, an insertion operation is taken as an example, and the method includes the following steps:

Step S301, the listening thread receives a Structured Query Language (SQL) statement query request, and allocates a worker thread to process the query request;

Step S302, the worker thread performs SQL query analysis and SQL query optimization to generate an execution plan;

Step S303, the worker thread adds an intent exclusive lock to the lock operation table, indicating that the write operation is to be performed on the table;

Step S304, the worker thread constructs an index item tuple (tuple) from the data record to be inserted, and locates Go to the first record that satisfies X<=tuple, and use the index to quickly locate the page to be inserted into the record, where X is the index record;

Step S305, determining whether a unique index is built on the table and the number of fields matching the cursor is greater than or equal to the number of unique key fields, and if so, executing step 306; otherwise, proceeding to step S314;

Step S306, constructing an index item tuple (tuple) from the data record to be inserted, and positioning the first record satisfying X>=tuple, where X is an index record;

Step S307, if the maximum transaction ID on the page is greater than or equal to the minimum transaction ID in the current active transaction, check whether there is an implicit lock on the current record, if yes, go to step S309; otherwise, go to step S308;

Step S308, the insertion operation is queued;

Step S309, acquiring a clustered index record corresponding to the current index record. If the record is just inserted, the record has an implicit lock, and the implicit lock is converted into an explicit lock;

Step S310, determining whether X=tuple is established, X=tuple indicating that there is a unique key conflict, and also indicating that the unique key constraint is violated, and performing step S311; if not, proceeding to step S312;

Step S311, reporting a duplicate key error, proceeds to step S305;

Step S312, sharing a lock on the record;

Step S313, relocating to the first record satisfying X<=tuple, X is an index record; Step S314, checking whether there is a lock on the next record of the current record, that is, calculating the file space number and page number of the record as the key Hash value, locates an entry on the lock hash table, traverses the linked list with the table entry as the header, checks whether the heap_no bit in the lock bitmap of each lock is set, if the lock bitmap The heap_no bit is not set, that is, there is no lock on the record, go to step S316; there is a lock on the record, go to step S315;

Step S315, if the first heap_no bit in the lock bitmap is set, it indicates that there is a lock on the record, continue to determine whether there is a lock conflict, if there is a lock conflict, go to step S308; otherwise, go to step S316; Step S316, applying for locking successfully, inserting data, preventing other transactions from modifying the record; Step S317, if there is a lock on the next record of the inserted record, inheriting the lock on the next record, and setting the waiting state to the granted state ;

Step S318, the transaction execution ends, that is, the transaction completes the commit or the transaction completes the rollback, releases the held lock, and scans the lock hash table lock queue to grant the lock that no longer needs to wait.

This embodiment is applied to a database system, such as a database system for an IPTV electronic program guide. Since each electronic program guide system can accommodate a limited number of users, an IPTV system requires a large number of electronic program listings. Each electronic program in the related art runs a commercial database in the background, resulting in high cost, and the embodiment adopts the above concurrency control method to reduce the cost while satisfying the performance of the commercial database, and better satisfies the IPTV system. Requirements, as well as standard database features, including transaction integrity, transaction concurrency control, failure recovery, and more. This embodiment effectively controls the concurrent execution of transactions while ensuring system performance to the greatest extent.

In this embodiment, the execution of the transaction includes a transaction completion submission or a transaction completion rollback, that is, when the transaction completes the commit or the transaction completes the rollback, the lock held by the transaction is released. In this embodiment, when the lock completes the locking task, it is released immediately, so that other concurrent transactions can obtain corresponding locks to obtain an opportunity to be executed, which helps to improve the concurrency of the control.

Preferably, in the above concurrency control method, the lock held by the release transaction specifically includes, for each lock in the linked list of the released lock, is deleted from the lock list, and is deleted from the corresponding lock hash table. .

In this embodiment, when the transaction execution ends, that is, when the transaction completes the commit or completes the rollback, the lock held by the transaction is deleted from the lock list corresponding to the transaction, and is also deleted from the corresponding lock hash table. In this embodiment, the lock is removed by deleting the lock from the corresponding lock list and the lock hash table. Release, the operation of the cartridge is easy, and when the lock completes the locking task for a transaction, it is released immediately, so that other concurrent transactions can obtain the corresponding lock to obtain the opportunity to be executed, which helps to improve the concurrency of the control.

In this embodiment, it is first detected whether there is a waiting flag in the lock type of the released lock. If there is a waiting flag, it indicates that the lock is in a waiting state, and then the hash is calculated by using the file space number and the page number of the lock locked record in the waiting state as a key. Value, locates the header of the corresponding linked list on the lock hash table, scans the linked list of the lock, checks whether each lock in the linked list has a lock type conflict with the lock, and if there is a lock type conflict, the detected lock It is possible to obtain a chance to grant a lock that is waiting for a lock type conflict with it; if there is no lock type conflict, the detected lock does not have to wait, grant the detected lock to other concurrent transactions, and wait for the lock to be reset. The flag changes the lock from the wait state to the grant state, and wakes up other concurrent transactions corresponding to the detected lock to continue execution.

4 is a structural diagram of a concurrency control apparatus according to a third embodiment of the present invention. As shown in FIG. 4, the apparatus includes:

The determining module 10 is configured to determine, according to the lock relationship table, whether the to-be-operated position of the transaction has a lock that conflicts with the lock to be granted, and the lock relationship table is configured to save the relationship between the transaction and the lock;

The execution module 20 is configured to grant a lock to the transaction according to the judgment result, and execute the transaction; the release module 30 is configured to release the lock held by the transaction when the execution of the transaction ends, and grant the lock of the released lock without waiting for the other Concurrent transactions.

In this embodiment, the determining module 10 first determines whether the to-be-operated position of the transaction has a lock that conflicts with the lock to be granted according to the lock relationship table, and then uses the execution module 20 to grant the transaction according to the judgment result. The lock is executed, and the transaction is executed. Finally, the release module 30 releases the lock held by the transaction when the execution of the transaction ends, and grants the lock in the released lock without waiting for the other concurrent transaction, because the lock relationship table is used to save the transaction and Corresponding lock relationship, it is possible to judge whether there is conflict in different locks pointing to the same to-be-operated position, and perform differential processing according to the judgment result, instead of being like the concurrency control method in the related art, once the position to be operated is locked All the transactions corresponding to other locks are included in the waiting queue, so the concurrency of the concurrency control method in the related art is low, the system performance is poor, and the concurrency of the transaction control is improved, and the concurrency is improved. Control effect.

As shown in FIG. 2, each entry of the lock hash table corresponds to a header of a linked list. In this way, the hash value is calculated by using the file space number and the page number recorded in the lock structure as keys, and then the The corresponding lock hash table entry is located to the corresponding linked list. The linked list is used to associate the records recorded in the transaction list with the locks recorded in the lock hash table. As shown in Figure 2, each linked list includes multiple lock structures, and each lock structure records the database of lock locks waiting in line. Recorded file space number, page number, lock bitmap, number of bits occupied by the lock bitmap, lock type (shared lock, exclusive lock), lock flag (waiting, grant), belonging transaction, etc. The first heap_no bit of the bitmap is the identifier of the location record to be operated. Each transaction corresponds to a linked list. Each transaction is applied to a lock list. The lock list holds the lock held by the transaction. Each pair of records is operated, and the corresponding The lock is inserted into the corresponding linked list of the transaction. A lock structure can be shared by other locks of the same type on the same page. If you need to add the same type of lock to other records, you only need to find the lock in the linked list. If you find it, you will lock the corresponding heap_no of the bitmap. The position bit, which solves the hash conflict by using a single linked list, and effectively saves memory space.

From the above description, it can be seen that the above-described embodiment of the present invention improves the concurrency of transaction control and improves the concurrency control effect.

Obviously, those skilled in the art should understand that the above modules or steps of the present invention can be implemented by a general-purpose computing device, which can be concentrated on a single computing device or distributed over a network composed of multiple computing devices. Alternatively, they may be implemented by program code executable by the computing device, such that they may be stored in the storage device by the computing device, or they may be separately fabricated into individual integrated circuit modules, or they may be Multiple modules or steps are made into a single integrated circuit module. Thus, the invention is not limited to any specific combination of hardware and software.

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. Any modifications, equivalent substitutions, improvements, etc. within the spirit and scope of the invention are intended to be included within the scope of the invention.

Claims

Claim

A concurrency control method, characterized in that the method comprises the following steps:

When the database is operated, it is determined according to the lock relationship table whether there is a lock in the to-be-operated position of the transaction that conflicts with the lock to be granted, and the lock relationship table is used to save the relationship between the transaction and the lock;

Granting a lock to the transaction according to the judgment result, and executing the transaction;

When the execution of the transaction ends, the lock held by the transaction is released, and the released lock of the lock that does not need to continue waiting is granted to other concurrent transactions.

The concurrency control method according to claim 1, wherein the lock relationship table specifically includes:

A transaction list that holds concurrently executed and uncommitted transactions;

a lock hash table for tracking locks waiting in line;

a linked list for associating the transaction with the lock.

The concurrency control method according to claim 2, wherein the granting a lock to the transaction according to the judgment result, and executing the transaction specifically includes:

The lock operation location of the transaction is unlocked, the lock is granted to the transaction, and the transaction is executed.

If the to-be-operated position of the transaction has a lock, it is checked whether there is a conflict between the existing lock and the to-be-granted lock;

A lock is granted to the transaction based on the result of the check, and the transaction is executed.

The concurrency control method according to claim 4, wherein the granting a lock to the transaction according to the check result, and executing the transaction specifically includes:

The existing lock does not conflict with the to-be-granted lock, and the lock is granted to the transaction, and the transaction is executed.

The existing lock conflicts with the pending grant, and the transaction is queued until the lock to be granted is regained;

Execute the transaction.

The concurrency control method according to claim 3, 5 or 6, wherein the executing the transaction comprises at least one of: performing an adding operation, performing a deleting operation, performing a modifying operation, and performing a reading operation.

The concurrency control method according to claim 1 or 2, wherein the end of the transaction execution comprises: the transaction completion submission or the transaction completion rollback.

The concurrency control method according to claim 1 or 2, wherein the granting the lock that does not need to continue waiting in the lock to be released to the other concurrent transaction specifically includes:

Detecting whether there is a wait flag for each lock in the linked list in which the lock is released; when there is a wait flag, and the other locks in the same operation position of the detected lock and the other concurrent transaction do not have a lock type In the event of a conflict, the lock to be detected is granted to the other concurrent transaction, and the other concurrent transaction is awakened to continue execution, the lock type including a shared lock and an exclusive lock.

10. A concurrent control device, the device comprising:

a determining module, configured to determine, according to the lock relationship table, whether the to-be-operated position of the transaction has a lock that conflicts with the lock to be granted, and the lock relationship table is configured to save the relationship between the transaction and the lock;

An execution module, configured to grant a lock to the transaction according to the judgment result, and execute the transaction; and release a module, when the execution of the transaction ends, release the lock held by the transaction, and release the lock A lock that does not need to wait for further grants other concurrent transactions.

The concurrency control device according to claim 10, wherein the lock relationship table specifically includes:

A transaction list that holds concurrently executed and uncommitted transactions; a lock hash table for tracking locks waiting in line;

a linked list for associating the transaction with the lock.

12. The concurrency control device according to claim 11, wherein

The execution module grants a lock to the transaction according to the judgment result, and executes the transaction as: the lock operation position of the transaction is unlocked, and the execution module grants a lock to the transaction, and executes the transaction.

13. The concurrency control device according to claim 11, wherein

The execution module grants a lock to the transaction according to the judgment result, and executes the transaction as: the operation at the to-be-operated location of the transaction has a lock, and the execution module checks whether the existing lock conflicts with the to-be-granted lock. ; grant a lock on the transaction based on the result of the check and execute the transaction.

14. The concurrency control device according to claim 13, wherein

The execution module grants a lock to the transaction according to the check result, and executes the transaction as follows: the existing lock does not conflict with the to-be-granted lock, and the execution module root grants a lock to the transaction, and executes The transaction.

15. The concurrency control device according to claim 13, wherein

The execution module grants a lock to the transaction according to the check result, and the executing the transaction is specifically: the existing lock conflicts with the pending grant, and the execution module sets the transaction to wait in a row until the device is regained The lock is granted, and the transaction is executed.

The concurrency control apparatus according to claim 12, 14 or 15, wherein the transaction executed by the execution module comprises at least one of: performing an adding operation, performing a deleting operation, performing a modifying operation, and performing a reading operation. .

The concurrency control device according to claim 10 or 11, wherein the releasing module grants the released locks without waiting for the lock to other concurrent transactions, and specifically includes: the chain of the locks released Each lock in the table detects whether there is a wait flag; when there is a wait flag, and the detected lock is at the same operational position as the other concurrent transaction When other locks do not have a lock type conflict, the lock to be detected is granted to the other concurrent transaction, and the other concurrent transaction is awakened to continue execution. The lock type includes a shared lock and an exclusive lock.