JP2001101221A - Data base access system and its method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a data base accessing system with excellent operability and responsiveness. SOLUTION: An asynchronous data base accessing method is normally performed by an application program 4, however, the method is switched to a synchronous data base accessing method if necessary. A query result buffering/ information part 11 can cope with both accessing methods. A query result acquiring part 8 and the query result buffering/informing part 11 are simultaneously operated in parallel as separate threads. The query result acquiring part 8 has a function to adjust the number of acquired records in each time so as to suitably shorten time intervals at which query results are successively acquired in the case of the asynchronous accessing method. The query result buffering/informing part 11 has a function to enable a user to cancel acquisition of the query results halfway in the case of the synchronous accessing method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for accessing a database.

[0002]

2. Description of the Related Art Generally, a method for accessing a database includes a synchronous access method and an asynchronous access method.
In the synchronous access method, an inquiry to the database (issuance of a query) and acquisition of a query result (search result) from the database are performed synchronously. Application that adopts synchronous access method (GUI part)
Issues a query to the database and waits until all query results (search results) have been obtained from the database without proceeding to other processing. After obtaining all the query results and displaying them in a GUI (for example, a list box), it becomes possible to proceed to other processing. Therefore, the user cannot perform another operation on the application until all the query results are obtained and displayed. In particular, when the load of the database or the load of the communication network with the database is high, the user has to wait for a long time,
The responsiveness and operability of the application decrease.

[0003] The asynchronous access method solves this problem. In this method, the inquiry to the database and the query result acquisition are performed asynchronously. In other words, an application that employs the same method only issues a query and then displays the query result in a list box only when the query result is notified by a message as an event. Other than that time, other processes can be performed. . Therefore, the user can perform other operations on the application without acquiring all the query results.

[0004]

In the asynchronous access method, after a query is issued, each time a message arrives, the obtained query result is sequentially displayed in a list box or the like of a GUI. It's hard to tell if you've finished getting all the query results or if you're not done yet. In particular, when it is necessary to display the query result completely until the end, and then proceed to the next operation, the above-mentioned inconsistency rather reduces the operability.

Accordingly, it is an object of the present invention to solve these problems and to provide a database access method excellent in operability and responsiveness.

[0006]

According to the present invention, there is provided a database access method which can be operated by a user, issues a query to a database, and receives notification of a query result from the database. Query result acquiring means for acquiring a query result for the obtained query from the database; and query result notifying means for notifying the application program of the query result acquired by the query result acquiring means. Then, the application program can access the database by selectively using the asynchronous database access method and the synchronous database access method,
In addition, the query result notifying means selectively uses an asynchronous method and a synchronous notification method corresponding to the asynchronous database access method and the synchronous database access method performed by the application program, and transmits the query result. The application is notified.

In a preferred embodiment, the application program accesses the database using a standard asynchronous access method, and switches from the asynchronous access method to the synchronous access method when requested by the user to access the database. I do.

[0008] In a preferred embodiment, the query result obtaining means has a function of adjusting the amount of query results obtained at a time from the database.

In a preferred embodiment, there is further provided means for canceling query result acquisition at the request of the user when the synchronous database access method is being performed.

[0010] In a preferred embodiment, the query acquisition means and the query result notification means can operate simultaneously and concurrently as separate threads.

[0011]

FIG. 1 shows the configuration of a database access system according to an embodiment of the present invention.

A client system 1 that uses a database is communicably connected to a database management system 3 that manages the database. The client system 1 and the database management system 3 are typically configured using different computer machines, and communicate with each other via a communication network connecting the machines. However, this is only an example, and other forms, for example, the client system 1 and the database management system 3 may be configured by the same computer machine.

The client system 1 includes an application program 4 for displaying a GUI (graphic user interface) on a screen, and a program (a GUI) 4 provided separately from the application program for actually performing database access. Database access unit) 13.

The database access unit 13 receives a query from the application program 4, issues the query to the database management system 3, issues a query result from the database management system 3, receives a query result from the database management system 3, and obtains an application program. 4 is a query result buffering / notification unit 11 for notifying the query result to three. Further, the database access unit 13
Has a common buffer 9 for temporarily storing query results.

The database query issuing unit 5 includes a query receiving unit 6 that receives a query from the application program 4 and a query actual issuing unit 7 that receives a query from the query receiving unit 6 and sends the query to the database management system 3. Query receiving unit 6 and actual query issuing unit 7
Belongs to another thread, as will be described later, so that they can operate simultaneously and in parallel, and pass a query between them using an inter-thread communication message.

The query result obtaining unit 8 obtains a query result (search result) from the database management system 3 and stores the query result in the common buffer 9. As will be described later, the query result obtaining unit 8 has a function of optimizing the number of records of the query results to be obtained at one time so that the query results can be sequentially obtained at predetermined desired time intervals.

Query result buffering / notification unit 11
Always monitors the common buffer 9 by polling, and when a query result enters the common buffer 9, notifies the application program 4 of the query result.
The query result buffering / notification unit 11 belongs to a different thread from the query result acquisition unit 8 as described later,
It can operate concurrently with the query result acquisition unit 8.

Query result buffering / notification unit 11
There are two methods for notifying the application program 4 of the query result: an "asynchronous" method and a "synchronous" method. The asynchronous method refers to the common buffer 9
Each time a query result is input to the application program 4, the query result is notified as an event to the application program 4 by a message. Application program 4
Needs to display the query result only when it receives the message, and can perform another process at other times.
That is, the application program 4 can operate by the asynchronous access method.

Query result buffering / notification unit 11
Notifies the application program 4 of the query result by the above asynchronous method. However, when a query result acquisition request is received from the application program 4, the asynchronous notification method is switched to the following synchronous notification method.

The synchronous notification method means that in response to a query result acquisition request from the application program 4,
This is a method of notifying the application program 4 of the requested query result. In this case, the application program 4 operates according to the synchronous access method, and does not proceed to other processing until all requested query results are notified.

When this synchronous notification method is used, the query result buffering / notification unit 11 determines whether or not it takes a certain time or more to acquire all the queries. It has a function of displaying a dialog box (see FIG. 6) on the screen and allowing the user to select whether to continue acquiring or cancel the query result. If the user selects cancel on that dialog box, the query result buffering /
The notification unit 11 returns a cancellation notification to the application program 4 instead of returning the query result, so that the application program 4 can exit from the process of receiving and displaying the query result and proceed to another process. Become.

The database access unit 1 having the above configuration
Reference numeral 3 denotes a component that cooperates with the application program 4 while communicating with the application program 4. For example, if a technology widely used in the Windows environment of Microsoft Corporation is used, an application is defined by a method defined by COM (Component Object Model). Ac working with and communicating with Program 4
tiveX components, which can be implemented as
However, this is only an example, and implementation using Java Beans or other component technologies is possible.
Also, the individual functional elements 5 (6, 8), 7, 11 can be implemented as separate components. Furthermore, a mounting method without using components is also possible.

This client system 1 uses Windows
By using an OS environment that supports multi-threads such as an environment, a plurality of threads operating in parallel, for example, an application program (that is, a GU)
I) 4 and functional elements that communicate with it, namely the query receiving unit 6 and the query result buffering / notifying unit 11,
A user interface thread 15 composed of
It can be divided into two threads, that is, a database access red 17 including a functional element for accessing the database, that is, a query actual issuing unit 7 and a query result obtaining unit 8. By dividing the user interface thread 15 and the database access red 17 in this way, the application program 4, ie, the GU
The operation of I and the database access operation can be performed concurrently. However, this is just an example, and other mounting methods are possible. For example, in an OS environment that does not support multi-threading, the method can be implemented by a method in which the database access 13 accesses the database when the application program 4 is idle in a message loop.

Here, a function of the query result obtaining unit 8 for optimizing the number of records of the query result obtained at one time will be described. When a query result consisting of a large number of records is received in total, such a large number of records are received at a time by dividing the appropriate small number of records into a plurality of times. In this case, this function estimates the load state of the database management system 3 or the communication network based on the number of records of the query result acquired last time and the time required for the acquisition, and the next acquisition time is a predetermined time. The number of records to be acquired next time is adjusted so as to obtain a desired value.

That is, the query result acquisition unit 8 sets the number of records to be acquired for the first time, but optimizes the number of records to be acquired for the second time and thereafter based on, for example, the following formula.

[0026]

(Equation 1) According to this formula, from the number r [n] of previously acquired records and the time t [n] required for the acquisition, the next acquisition that is expected to be optimal for obtaining a response with a predetermined desired response time T is performed. The number of records r [n + 1] is determined. For example, if the desired response time T is set to 1.6 seconds, and the number r [1] of first acquired records is set to 10 records, and the time t [1] required for the first acquisition is 3.0 seconds, The query result acquisition unit 8 calculates the number r [2] of acquired records for the second time as 1.0 × 1.
By the calculation of 6 / 3.0 ≒ 5, 5 records are determined.
It should be noted that the above calculation formula is merely one of the simplest examples, and a more complicated calculation formula can be used.

The query result obtaining unit 8 can control the query result obtaining time for each time to a desired time by determining the suitable number of records to be obtained at one time each time in this way. As a result, even if the load on the database management system 3 or the communication network slightly increases, the user does not have to wait an abnormally long time until the next query result is displayed on the GUI.
This is especially true for asynchronous access methods.
Until all the query results have been obtained, the subsequent query results are additionally displayed on the GUI at substantially desired response time intervals, so that it is easy to determine whether all the query results have been obtained.

Hereinafter, the operation of the client system 1 under the above configuration will be described in detail.

The application program 4 is a GUI
Is displayed on the screen. FIG. 2 shows an example of the GUI. This example is a window 20 for registering a customer in the business support system, and fields 21, 23, and 25 for entering a customer's name, date of birth, address and the like.
And an execute button 27 for executing a database search for information that can be entered in those fields, and a list box 29 for displaying the search results (query results)
and so on. When the user requests a query on this GUI (for example, when the execute button 27 is clicked),
The application program 4 sends the query to the query receiving unit 6 of the database access unit 13.

In the database access unit 13, the query receiving unit 6 passes the query received from the application program 4 to the query actual issue processing unit 8, and the query actual issue unit 7 sends the query to the database management system 3.
Send to Then, the query result obtaining unit 8 sequentially receives the query results for each appropriate number of records from the database management system 3 as described above, and stores the query results in the common buffer 9. The query result buffering / notification unit 11 constantly monitors the common buffer 9 by polling, and when a query result enters therein, notifies the application program 4 of the query result.

The notification of the query result to the application program 4 is performed in a standard asynchronous manner as described above. That is, the query result buffering / notifying unit 11 notifies the application program 4 of the query result sequentially entering the common buffer 9 by using a message as an event each time. Each time the application program 4 receives the message, the notified query result is displayed in a list box, for example, as shown in FIG. 3 (FIG. 3 shows an example of searching for a municipal name that can be entered in the address field 25). 29
Add more entries. As described above, since the notification of the query result comes at a substantially desired response time interval, additional entries of the subsequent query result are made in the list box 29 at the short time interval. As long as the additional entries continue in the short time interval, the user can know that the retrieval of all query results has not been completed yet. Further, during the asynchronous query acquisition, the user performs other processing other than query result acquisition, such as entering a name in the name field 21 as shown in FIG. 4
Can be performed.

As described above, the application program 4 normally uses the asynchronous access method, but switches to the synchronous access method according to the user's request.
As a trigger for switching, the user pulls down the scroll bar 31 of the list box 29 to the bottom as shown in FIG.
As an example, a case where a request to display the query results of all the users, such as when "d" is input, can be given. When such a user request is made, the application program 4 switches from the asynchronous access method to the synchronous access method, and sends a query result acquisition request to the query result buffering / notification unit 11 of the database access unit 13 for processing call. Send in form. The query result buffering / notification unit 11 returns all requested query results to the application program 4 in the form of a callback for a process call, not in the form of a message for notifying an event. The application program 4 waits for the callback from the query result buffering / notification unit 11 without proceeding to other processing, and upon receiving the callback, lists the query result notified thereby as shown in FIG. It is displayed in box 29.

When a query result acquisition request is received from the application program 4 as described above, the query result buffering / notification unit 11 estimates whether or not it will take a certain time or more to acquire all the requested query results. And
If it is estimated that such is the case, a dialog box 40 as shown in FIG. 6 is displayed on the screen. The dialog box 40 includes a message 41 for notifying the user that all query results are currently being read (that is, performing a synchronous access method), and a percentage of all records to be read. It includes a bar graph 43 indicating whether or not the query has already been read, and a cancel button 45 for canceling the acquisition of the query result in the middle. The user can predict the acquisition time of all query results from the bar graph 43 in the dialog box 40, and can cancel the query result acquisition halfway by clicking the cancel button 45. When the cancel button 45 is clicked, the query result buffering / notification unit 11 notifies the application program 4 of the cancellation in the form of a callback. Upon receiving the callback, the application program 4 exits from the process of acquiring the query result, so that the user can perform another operation on the application program 4.

According to the above-described embodiment, since the advantages of the synchronous access method and the asynchronous access method are utilized and the disadvantages are improved, the responsiveness and operability of database access can be improved. In particular, the effect of the present invention is great in an environment where a database must be accessed through a low-speed or unstable communication network such as a mobile environment.

Although the preferred embodiment of the present invention has been described above, this is an exemplification for describing the present invention, and is not intended to limit the scope of the present invention only to this embodiment.

[Brief description of the drawings]

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

FIG. 2 is a diagram illustrating an example of a GUI of an application.

FIG. 3 is a view showing a display example of a GUI when a database is accessed by an asynchronous access method.

FIG. 4 is a diagram showing a display example of a GUI when another operation is performed during acquisition of a query result when a database access is performed by an asynchronous access method.

FIG. 5 is a view showing a display example of a GUI when a database is accessed by a synchronous access method.

FIG. 6 is a view showing a display example of a dialog box for cancellation displayed when it takes time to access a database by a synchronous access method.

[Explanation of symbols]

 Reference Signs List 1 client system 3 database management system 4 application program 5 database query issuing unit 6 query receiving unit 7 query actual issuing unit 8 query result obtaining unit 9 common buffer 11 query result buffering / notifying unit 13 database access unit 15 user interface thread 17 database Access thread

Claims (12)

[Claims] 1. An application program that can be operated by a user, issues a query to a database, and receives a notification of a query result from the database; and obtains a query result for the query issued from the application program from the database. Query result notifying means, and a query result notifying means for notifying the application of the query result obtained by the query result obtaining means, wherein the application program executes an asynchronous database access method and a synchronous database access method. The query result notifying means may be an asynchronous corresponding to an asynchronous database access method and a synchronous database access method performed by the application program. Selectively using the method and synchronous notification method,
Notifying the application of the query result,
Database access method. 2. The method according to claim 1, wherein the application program performs the asynchronous database access method in a standard manner, and switches from the asynchronous database access method to the synchronous database access method in response to a user request. Database access method. 3. The database access method according to claim 2, wherein said query result obtaining means has means for adjusting an amount of said query result obtained at one time from said database. 4. The database access method according to claim 1, further comprising means for canceling a query result acquisition by a user request when the synchronous database access method is being performed. 5. The database access method according to claim 1, wherein the query acquisition unit and the query result notification unit are configured as separate threads, and can operate simultaneously in parallel. 6. A step of obtaining a query result for a query issued from an application program from a database, and when the application program performs an asynchronous database access method, the query result obtained from the database is converted to the asynchronous result. Notifying the application using an asynchronous notification method corresponding to the database access method, and, when the application program performs a synchronous database access method, the query result obtained from the database is transmitted to the synchronous database. Notifying the application using a synchronous notification method corresponding to the access method. 7. A query result obtaining step of obtaining a query result for a query issued from an application program from a database; and a query result obtained from the database when the application program performs an asynchronous database access method. An asynchronous result notification step of notifying the application using an asynchronous notification method corresponding to the asynchronous database access method; and a query result obtained from the database when the application program performs a synchronous database access method. A synchronous result notifying step of notifying the application with a synchronous notifying method corresponding to the synchronous database accessing method. Carrying computer readable recording medium. 8. The program normally causes the computer to perform the asynchronous result notification step, and when the application program receives a query result acquisition request, sends the synchronous result notification step to the computer. The computer-readable recording medium according to claim 7, wherein: 9. The computer-readable recording medium according to claim 7, wherein the program causes the computer to further perform a step of adjusting an amount of the query result obtained at one time in the query result obtaining step. 10. The program causes the computer to cancel the synchronous result notifying step when there is a cancellation request from a user while the program causes the computer to perform the synchronous result notifying step. Item 8. A computer-readable recording medium according to Item 7. 11. The computer-readable computer according to claim 7, wherein the program causes the computer to perform the query result acquisition step and the asynchronous result notification step or the synchronous result notification step concurrently. Recording medium. 12. Displaying a GUI, accessing a database by selectively using an asynchronous database access method and a synchronous database access method, and displaying a query result obtained by accessing the database. A computer-readable recording medium carrying a program for causing a computer to execute the steps of displaying on the GUI.