JPH06243014A - Data base system - Google Patents

Abstract

PURPOSE:To prevent the locking release omission of data, to reduce the waiting time for data reference during a locking and to prevent the deterioration in processing efficiency due to the locking of data. CONSTITUTION:A data base 34, a data base management part 33 receiving write/read/locking and locking release requests to the data base from a data base user and processing them, a locking time monitor timer 35' clocking up to the time designated at the time of the locking request from the locking start of a record by the locking request (locking operation instruction) and a locking time monitor part 35 informing the data base management part of time-out when the locking time monitor time 35' is timed out, are contained. The locking request can select/designate either a complete locking function inhibiting both read/write functions or a write locking function enabling reading and inhibiting writing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lock function for locking reading and writing in a database of a database system.

[0002]

2. Description of the Related Art In recent years, in order to improve the logicality and operability of data, a database system for centrally managing data as a database has been widely introduced. The conventional database system will be described below.

Conventionally, as a database system, for example, a system having a structure shown in the block diagram of FIG. 7 has been adopted. In FIG. 7, 1 is a database system, and 2 is an input / output terminal for a database user to input a command to the database system 1 and to receive a response from the database system 1 to display it.

Reference numeral 3 is a database management unit for receiving and controlling and processing a database operation request from a database user, 4 is a database for logically systematizing and storing data of the database user, and 5 is an input / output terminal 2. Is an input / output control unit that is connected between the input / output terminal 2 and the database management unit 3 and that controls the input / output of data to / from the input / output terminal 2 and the database management unit 3.

The database management unit 3, the database 4, and the input / output control unit 5 are configured to be included in the database system 1. The operation of the conventional database system thus configured will be described below.
First, the database user uses the input / output terminal 2 to execute a login procedure, that is, a login procedure. At this time, the database user specifies a management number called a user code for identifying the database user through the login procedure. The user code is unique to each database user.

When the login procedure is completed, the database user can receive the database service from the database system. Database 4
The internal storage area is divided into logical units called records. The data stored in the database 4 is grouped according to its type and stored in a record. Writing and reading operations for data in the database 4 are performed in record units. Therefore, when requesting a data operation (writing or reading, etc.) to the database system 1, information (identification information) called a record number for identifying a record is designated.

FIG. 8 is a schematic diagram showing an outline of the internal structure in the database 4. In FIG. 8, reference numeral 6 represents the relationship between the record number (record 1, record 2, record 3, record 4, ..., Record N) and data area (7, 8, 9, 10, ..., N) for each of the above records. In the data area 7, the record 2 in the data area 8,
In the record N, identification information corresponding to the data area N is written.

[0008] Table 1 below shows an example of a specific format of an operation command for requesting an operation for operating the database 4 input by the database user to the input / output terminal 2. In Table 1, reference numeral 11 is a format of a read operation instruction for reading the database 4, and three pieces of information of a user code, a record number, and a read data length are designated as parameters. Similarly, 12 is a format of a write operation command for writing to the database 4, and three pieces of information of a user code, a record number, and write data are designated as parameters.

Table 1 Read operation command "READ": (User code, record number, read data length) ... 11 Write operation command "WRITE": (User code, record number, write data)・ 12 Lock operation command "LOCK": (User code, record number) ・ ・ ・ 13 Lock release operation command "UNLOCK": (User code, record number) ・ ・ ・ 14

Further, the database system 1 is provided with a lock function for protecting the designated record from the operation by other database users until the updating work of the database 4 is completed.

In Table 1, reference numeral 13 represents a format of a lock operation command for the database 4, which specifies a user code and a record number as parameters. Similarly, 14
Is a format of an unlock operation command for the database 4, and specifies a user code and a record number as parameters.

FIG. 9 is provided in the database management unit 3,
It is a figure which shows the lock information table for storing the information regarding a lock operation. The lock information table contains
The user code 16 of the database user who requests the lock operation that is set only when the lock is set (the lock state is set) and the lock state 15 corresponding to all the records that can be specified by the record number Remembered.

In the conventional database system 1 as described above, when updating the data in the database 4, first, the data is locked, and then the data write operation is performed, and when the data update is completed. The data was updated according to the procedure of unlocking the lock. With this lock function, it is possible to prohibit other database users from reading or writing the data during updating or changing.

FIG. 10 is a flow chart showing a data reading process in the conventional database system 1.
FIG. 11 is a flowchart showing a data writing process in the conventional database system 1. That is, the database management unit 3 performs the reading process and the writing process according to the procedure shown in FIGS.

The reading process and the writing process by the conventional database system 1 will be described below with reference to FIGS. 10 and 11. The database user who has completed the login procedure inputs a data read operation command shown in 11 of Table 1 from the input / output terminal 2. The read operation command includes, as parameters, the record number of the record in which the data to be read is stored, the size (data length) of the data to be read, and the user code of the database user. The read operation command is notified to the database management unit 3 via the input / output control unit 5 in the database system 1.

In the flowchart of FIG. 10, when the reading process is started, first, in step S61 (in the figure, simply S6 is performed).
1), the database management unit 3 that has received the read operation command uses the record number designated by the read operation command (11 in Table 1) to record that record in the lock information table (FIG. 9). The lock information for the record is acquired from the item in the lock status corresponding to the number. Therefore, the process proceeds to step 62, and it is checked whether or not there is a locked display in the item of the lock state of the corresponding record number that has just been acquired. If there is no locked display, the process proceeds to step 65 where the record number is designated. The data is read from the recorded record of the database 4, and the read data is sent back to the input / output terminal 2 via the input / output control unit 5 and displayed there. Further, the operation proceeds to step 66, notifies "normal end", and ends the process.

When it is determined in step 62 that the specified record is locked, the process proceeds to step 63, where the user code is checked. If the user code is his / her own, the lock is requested by himself / herself, and therefore the process proceeds to step 65, where the data is read from the record of the database 4 designated by the record number, and the input / output control unit is again executed. The data read via 5 is returned to the input / output terminal 2 and displayed there. The operation proceeds to step 66, notifies "normal end", and ends the processing.

If it is found in step 63 (meaning that the specified record is locked) that the person requesting the lock is another database user, the process proceeds to step 64 and the specified record is A message indicating that “reading is not possible because the lock is being performed” is notified to the input / output terminal 2 via the input / output control unit 5 to be displayed, and the reading operation is completed.

Next, the writing process shown in the flowchart of FIG. 11 will be described. This writing process is almost the same as the reading process shown in FIG. 10, except that it is different.
In step 75, data is read from the record of the database designated by the record number (step 6
5) Instead, write the data there. Therefore,
Description of the overall flow of the flowchart of FIG. 11 is omitted.

The lock processing and unlock processing of the conventional database system will be described below with reference to the flowcharts of FIGS. 12 and 13. In FIG.
The locking process starts when the database user who has completed the login procedure inputs a data locking operation command (13 in Table 1) from the input / output terminal 2 (FIG. 7), and proceeds to step 81.

As described above, the lock operation command has parameters including the record number of the record in which the data is stored and the user code of the database user, and controls the input / output control unit 5 of the database system 1. It is transmitted to the database management unit 3 via the. The database management unit 5 that has received the lock operation instruction uses the record number designated by the operation instruction to acquire the lock information from the item (lock state) corresponding to the number in the lock information table (FIG. 9) ( Step 81).

Therefore, the routine proceeds to step 82, where it is checked whether or not the record designated by the record number has a locked display. If there is no locked display, the routine proceeds to step 86 and the lock information table of FIG. Set the required status for the corresponding item of the specified record number. For example, the character of "locked" or a code indicating the same is stored in the item of the lock state of the record number, and the process proceeds to step 87. In step 87, the user code of the user who requested the lock is stored in the item of the user code of the same record number, the process proceeds to step 88, and the lock process is “normally completed” via the input / output control unit 5. A message indicating that is notified to the input / output terminal 2 to be displayed, and the processing ends.

When it is determined in step 82 that the designated record is locked, the flow advances to step 83, where the user code is checked. If the user code is his / her own, the lock is requested by himself / herself, and therefore the process proceeds to step 84, where a message indicating that "locking" is already performed is input / output via the input / output control unit 5. Notify the terminal 2 and display it there.

In step 83 (meaning that the specified record is locked), if it is found that the person who requested the lock is another database user, the process proceeds to step 85, in which the input / output control unit 5 is set. Via this, the designated record is notified to the input / output terminal 2 to display a message indicating that "another user is locked", and the processing is terminated.

Next, the unlocking process shown in the flowchart of FIG. 13 will be described. This lock release processing is almost the same as the lock processing shown in FIG. 11, but is slightly different in the following points. That is, in step 92, if the record designated by the record number does not indicate that the record is locked, the process proceeds to step 98, and a message indicating "unlocked" is issued via the input / output control unit 5 to the input / output terminal 2 To notify and display, and the process ends.

When it is found in step 92 that the specified record is locked, the flow advances to step 93, where the user code is checked. If the user code is his own, the lock is requested by himself, so the process proceeds to step 95, and the display of "locked" in the locked item of the lock information table specified by the record number is erased. Then, it proceeds to step 96. In step 96, the user code item designated by the same record number is erased, and the flow advances to step 97 to notify the input / output terminal 2 of a message indicating that the lock release process is “normally completed” and display the message. , The process ends.

If it is found in step 93 that the person who requested the lock is another database user, the process proceeds to step 94, and the specified record indicates that "the other user is in the lock". The message shown is notified to the input / output terminal 2 and displayed, and the processing ends.

[0028]

However, in the conventional configuration described above, the database is not unlocked even after the database user has finished the necessary operation such as updating the database, and the database remains in the locked state for a long time. If left unattended, the record designated as locked cannot be read or written by other database users. Therefore, the processing was delayed, and in some cases, the database system could deadlock. Further, during the lock, even a database user who does not need to write and only needs to refer to the record has to stop the processing.
There is a problem that it causes a great decrease in the processing efficiency of the database service.

Therefore, an object of the present invention is to make it possible to detect a lock release omission in the database and automatically (compulsively) release the lock if the lock release omission occurs. This is to make it possible to refer to the data and prevent the deterioration of the processing efficiency of the data service.

[0030]

In order to achieve the above-mentioned object, the database system according to the present invention firstly provides a lock for monitoring the time from the lock setting to the lock release of the record corresponding to each record number in the database. A time monitoring unit is provided to automatically release the lock and display it after a predetermined lock time has elapsed in the locked state. Second, a complete lock function that prohibits both writing and reading functions. It is characterized by having two lock functions, a lock and a write lock that allows reading but prohibits only writing.

[0031]

According to the present invention, when a particular record in the database is locked, a timer is set by designating the time, and when the designated time expires, the record is regarded as an unlock failure and the lock is automatically released. By doing so, it prevents the lock state from being left unreasonably long, and
By designating the write lock, it is possible to perform a read operation from another database user even in the locked state and improve the processing efficiency of the database service.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A database system according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a block diagram showing the configuration of a database system according to an embodiment of the present invention.

In FIG. 1, 31 is a database system according to the present invention, and 32 is an input / output for a database user to input a command to the database system 31, receive a response from the database system 31 and display it. It is a terminal. Reference numeral 33 is a database management unit that receives a database operation request from a database user and controls and processes it.

Reference numeral 34 is a database which logically systematizes and stores the data of the database user, and 35 'is a lock which keeps time from the lock start of the record of the database designated by the lock operation command to the time designated by the lock operation command. The time monitoring timer 35 monitors the time from the lock start to release of the designated record by the lock time monitoring timer 35 '. When the lock is released, the monitoring is stopped and the lock is released until after the designated time elapses. If not, a lock time monitoring unit for stopping the monitoring and notifying it to the database management unit 33 to forcibly release the lock, 36 is provided between the input / output terminal 32 and the database management unit 33. It is an input / output control unit that is connected and performs input / output and control of data between them.

In this embodiment, the database management unit 33, the database 34, the lock time monitoring unit 35, and the input / output control unit 36 are included in the database system 31. However, they may be external to the database system. Further, the lock function of the database system 31 has two lock functions: a complete lock that prohibits both writing and reading functions, and a write lock that allows reading but only writing.

Next, the operation of the database system according to the embodiment of the present invention constructed as described above will be explained. First, the database user uses the input / output terminal 32 to execute the login procedure as in the conventional example described above. At this time, the database user specifies the user code through the login procedure and logs in. When the login procedure is completed, the database user can receive the database service from the database system.

The database 34 is composed of a plurality of records as in the conventional example, and may be structured as shown in FIG. 8, for example. Further, the writing and reading operations for the data of the database 34 can be performed in the record unit designated by the record number, as in the above-mentioned conventional example.

Table 2 below shows an example of the format of the operation command input to the input / output terminal 32 by the database user to request the operation of the database 34. In Table 2, 3
Reference numeral 7 denotes a read operation command format for reading the database 34, which includes a user code, a record number, and a read data length.
The three types of information are specified as parameters. Similarly, 3
Reference numeral 8 is a format of a write operation command for writing to the database 34, and specifies three pieces of information of a user code, a record number, and write data as parameters.

Table 2 Read Operation Command "READ": (User Code, Record Number, Read Data Length) ... 37 Write Operation Command "WRITE": (User Code, Record Number, Write Data) ... -38 Lock operation command "LOCK": (User code, record number, locking method, lock time) ... 39 Lock release operation command "UNLOCK": (User code, record number) ... 40

Further, the database system 31 is provided with a lock function for protecting the designated record from the operation by another database user until the update work of the database 34 is completed. As the lock function according to the present invention, as shown in the embodiments described below, the database system 31 is provided with two lock functions. One is a full lock that prohibits both writing and reading to protect the specified record from manipulation by other database users, and the other is a write lock that allows reading but prohibits writing. .

In order to specify each of the lock functions, the lock operation instruction according to the present invention takes the form of the lock operation instruction for the database 34 as indicated by 39 in Table 2.
In this lock operation command, in addition to the user code and record number, four pieces of information in which a record lock method and lock time are added are designated as parameters. Again 4
0 is the format of the unlock operation command for the database 34, and the user code and the record number should be specified as parameters, as in the case of the prior art described above.

FIG. 2 is a diagram showing a lock information table provided in the database management unit 33 for storing information on lock operations. In the lock information table, the lock status of all the records that can be specified by the record number, that is, a display 41 indicating that the record is completely locked or write locked, and a database requesting a lock operation to be recorded only when either lock is used The user code 42 of the person and the lock time 43 indicating the valid time of the lock request according to the present invention are stored.

In the database system 31 according to the embodiment of the present invention, when updating the data in the database 34, first, the record or the data is locked, and then the data write operation is performed to complete the data update. At that time, the data is updated according to the processing procedure of releasing the lock. By the action of this lock function, other database users are prevented from writing to the data that is being changed, and the occurrence of logical inconsistency of data that may occur due to the absence of such a prevention function is prevented.

FIG. 3 is a flow chart showing a process of reading data from the database 34 in the database system 31 according to one embodiment of the present invention, and FIG. 4 is a flow chart showing a process of writing data to the database 34. That is, the database management unit 33 is shown in FIG.
The read process and the write process are executed according to the procedure shown in FIG.

The database system 3 according to one embodiment of the present invention will be described below with reference to the flowcharts of FIGS. 3 and 4.
The reading process and the writing process of No. 1 will be described in detail. The database user who has completed the login procedure inputs a data read operation command shown in 37 of Table 2 from the input / output terminal 32. The read operation command includes, as parameters, the record number of the record in which the data to be read from the database 34 is stored, the size (data length) of the data to be read, and the user code of the database user. The read operation command is notified to the database management unit 33 via the input / output control unit 36 in the database system 31.

In the flow chart of FIG. 3, when the read processing is started, first, the database management unit 33 that has received the read operation command uses the record number designated by the read operation command (37 in Table 2) to perform the lock operation. The lock information for the record is acquired from the locked item (41 in FIG. 2) corresponding to the record number in the information table (FIG. 2) (step 1). Therefore, the process proceeds to step 2 and it is checked whether or not the lock information of the corresponding record number acquired just now indicates "completely locked".

If the lock is not completely locked, the process proceeds to step 5, where the data is read from the record in the database 34 designated by the record number, and the read data is again sent to the input / output terminal 32 via the input / output control unit 36. Return and display. Further, the operation proceeds to step 6, notifies "normal end", and ends the process. As can be seen from the above description, in the case of a read operation, according to the purpose of the present invention,
Since the read operation can be executed by another database user during the write lock, it is not necessary to check whether or not the write lock is in effect, and therefore there is no step to judge it.

When it is found in step 2 that the specified record is completely locked, the process proceeds to step 3 where the user code is checked. If the user code is his / her own, the complete lock is requested by himself / herself, and the process proceeds to step 5, where the data is read from the record of the database 34 designated by the record number and the input / output control is performed again. The read data is returned to the input / output terminal 32 via the unit 36 and is displayed there. Further, the operation proceeds to step 6, where a "normal end" is notified and the processing is ended.

When it is found in step 3 (meaning that the specified record is in complete lock) that the user who requested the complete lock is another database user, the process proceeds to step 4 and the I / O control is performed. A message indicating that the record specified via the unit 36 is "completely locked" cannot be read and is displayed on the input / output terminal 32, and the read operation is terminated.

Next, the writing process for writing data in the database 34 designated by the record number will be described with reference to the flowchart of FIG. In the case of the write processing, as described above, the write is prohibited during both the complete lock and the write lock. First, after the database user has completed the login procedure,
From the input / output terminal 32, a write operation command as indicated by 38 in Table 2 is input.

The write operation command includes the record number in which the data to be written is stored as the parameter, the size of the write data, the data to be written, and the user code of the database user. The write operation command is transmitted to the database management unit 33 via the input / output control unit 36 of the database system 31.

In response to the write operation command, the database management unit 33 receives the lock information (unlocked state, complete lock information) for the record designated by the record number from the lock information table shown in FIG. 2 as shown in step 11 of FIG. The lock state or the light lock state) is acquired and the process proceeds to step 12. If it is determined in step 12 and step 13 that the designated record is neither completely locked nor write locked, the process proceeds to step 16. In step 16, the data is written in the record of the database 34 designated by the record number, and the process proceeds to step 17 to return the "normal end" message to the input / output terminal 32 via the input / output control unit 36 for display. , The process ends.

When the specified record is judged to be completely locked or light locked in step 12 or step 13, the process proceeds to step 14 and the user code is checked. If the user code is his / her own, the lock is requested by himself / herself, so that it is not necessary to prohibit writing, and the process proceeds to step 16, and the data is written in the record of the designated database 34 as described above. Therefore, the process proceeds to step 17, in which the message indicating "normal end" is notified to the input / output terminal 32 via the input / output control unit 36 to be displayed, and the process is ended.

In step 14 (meaning that the specified record is in full lock or write lock), it is determined by the user code that the write operation was requested by another database user. Once it turns out,
The process proceeds to step 15, and the record designated via the input / output control unit 36 is "locked", so a message indicating that the record cannot be written is notified to the input / output terminal 32 and displayed, and the process ends. To do.

Next, the lock operation of the database system according to the embodiment of the present invention will be described with reference to the flowchart of FIG. After completing the login procedure, the database user inputs a record lock operation command as shown in 39 of Table 2 from the input / output terminal 32. The lock operation command includes, as its parameters, the record number of the record in which the data to be locked is stored, the user code of the database user, the lock method indicating the complete lock or the light lock, and the desired lock time. .

In FIG. 5, when the database management unit 33 receives the lock operation command input from the input / output terminal 32 via the input / output control unit 36, the process proceeds to step 21.
The lock information (unlocked state, complete lock state, or write lock state) for the record specified by the record number is acquired from the lock information table shown in FIG.

In steps 22 and 23,
If it is determined that the respective designated records are neither completely locked nor light locked (non-locked state), the process proceeds to step 27. In step 27, the database management unit 33 activates the lock time monitoring timer 35 'for the designated record, and proceeds to step 28, as shown in FIG.
Set the lock time specified in the lock time item in the corresponding record number of the lock information table shown in.

Next, the process proceeds from step 29 to step 30 to set the user code of the designated record and the desired lock state (complete lock state or light lock state) of the record. After storing and setting in the corresponding item of the lock information table, the process proceeds to step 31, and the input / output terminal 32 is notified and displayed via the input / output control unit 36 that the process is “normally completed”.
The process ends.

If it is determined in step 22 or step 23 that the designated record is completely locked or light locked, the process proceeds to step 24, and the user code is checked. If the user code is his own, the lock is requested by himself, so the process proceeds to step 25, and the record designated via the input / output control unit 36 is "already locked". The message is notified to the input / output terminal 32 to be displayed, and the processing ends.

At step 24 (meaning that the specified record is in full lock or write lock), it is found that the lock state is locked by another database user. Then, the record designated via the input / output control unit 36 is notified to the input / output terminal 32 to display a message that "the other database user is locked", and is displayed.
The process ends.

Next, the unlocking operation of the database system according to the embodiment of the present invention will be described with reference to FIG. After completing the login procedure, the database user inputs a data unlock operation command as shown by 40 in Table 2 from the input / output terminal 32. The unlock operation command includes, as its parameters, the record number of the record storing the data to be unlocked and the user code of the database user.

In FIG. 6, when the database management unit 33 receives the lock release operation command input from the input / output terminal 32 via the input / output control unit 36, the process proceeds to step 41 and records from the lock information table shown in FIG. The lock information (non-lock state, complete lock state, or write lock state) for the record designated by the number is acquired, and the process proceeds to step 42.

In steps 42 and 43,
If it is determined that the designated records are neither completely locked nor light locked (non-locked state), the process proceeds to step 51. In step 51, the database management unit 33 notifies the input / output terminal 32 of a message indicating that the designated record is “unlocked” via the input / output control unit 36, and displays the message, and the processing ends. .

If it is determined in step 42 or step 43 that the designated record is completely locked or light locked, the process proceeds to step 44, and the user code is checked. If the user code is his / her own, the lock is requested by himself / herself, and therefore, the process proceeds to step 46, and the lock of each designated record is sequentially passed through step 47, step 48 and step 49. The time monitoring timer is released, the lock time for the specified record in the lock information table is deleted, the user code of the specified record is deleted, the locking method of the specified record is deleted, and the process proceeds to step 50. In step 50, the input / output control unit 3
A message indicating that the unlocking process is “normally completed” is notified to the input / output terminal 32 via 6 and displayed, and the process ends.

At step 44 (meaning that the specified record is in full lock or write lock), it is found that the lock state is locked by another database user. The record designated via the input / output control unit 36 is “locked by another user”, and the input / output terminal 32 is notified of the message indicating that the record cannot be unlocked and displayed. , The process ends.

As described above, when the lock state of the specified record is left unlocked for the specified time (the setting time of the lock time monitoring timer 35 'specified by the lock operation command 39) from the start of locking. The lock time monitoring timer 35 'times out.
When this timeout occurs, the lock time monitoring unit 35
Notifies and displays a message indicating that the locked state has been forcibly released to the input / output terminal 32 to which the database user who requested the lock has logged in, and displays the corresponding item for the specified record in the lock information table. to erase. In this way, the neglected lock state is automatically released after a lapse of a predetermined time, and any database user can freely read and write, thus preventing a decrease in processing efficiency.

[0067]

The present invention is configured as described above,
In particular, the lock release timer is set to a specified time when setting the lock, and the lock release is forcibly released when it times out, so that the lock release omission does not occur and the deadlock of the database system is avoided. Became possible. Further, according to the present invention, as the lock function for locking the reading and writing of the record of the database, a complete lock for locking both the writing and the reading, and a write lock function for prohibiting only the writing and enabling the reading can be set. In this way, the data is not locked more than necessary for the read request, and the waiting time until the lock is released can be eliminated, so that the processing efficiency of the database service that may occur in the database update processing etc. It became possible to prevent the decrease.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a database system according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a lock information table set in a database system according to an embodiment of the present invention.

FIG. 3 is a flowchart showing a reading process by a database management unit according to an embodiment of the present invention.

FIG. 4 is a flowchart showing a writing process by the database management unit according to the embodiment of this invention.

FIG. 5 is a flowchart showing lock processing by the database management unit according to the embodiment of this invention.

FIG. 6 is a flowchart showing lock release processing by the database management unit according to the embodiment of this invention.

FIG. 7 is a block diagram showing the configuration of a conventional database system.

FIG. 8 is a schematic diagram showing the internal structure of a conventional database.

FIG. 9 is a configuration diagram of a lock information table set in a conventional database system.

FIG. 10 is a flowchart showing a reading process of a conventional database management unit.

FIG. 11 is a flowchart showing a writing process of a conventional database management unit.

FIG. 12 is a flowchart showing lock processing of a conventional database management unit.

FIG. 13 is a flowchart showing lock release processing of a conventional database management unit.

[Explanation of symbols]

 1 database system 2 input / output terminal 3 database management unit 4 database 5 input / output control unit 6 record table 7, 8, 9, 10, N data area 31 database system 32 input / output terminal 33 database management unit 34 database 35 lock time monitoring unit 36 I / O controller

Claims (2)

[Claims] 1. A database system comprising: a database; and a database management unit for processing in response to a write request, a read request, a lock request, and an unlock request for the database from a database user. When a lock time monitoring timer that clocks from the lock start of the record of the database specified by the lock request to the time specified by the lock request, and when the lock time monitoring timer is monitored to time out while the record is locked And a lock time monitoring unit for notifying the database management unit of this and releasing the lock state set by the lock request and displaying the lock state. 2. The lock request selectively specifies a complete lock function of prohibiting writing and reading of a designated record and a write lock function of prohibiting only writing and being readable in the lock request. The database system according to claim 1.