JPH01187632A - Query processing methods for distributed database management systems - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a query processing method for a distributed database management system, and is particularly suitable for accessing table data scattered between a host computer and a workstation in a simple manner. Regarding query processing methods.

[Conventional technology]

As described in Japanese Patent Application Laid-Open No. 59-108155, the conventional method is a distributed database management system configured using multiple computers and communication lines connecting them, and queries of table data distributed among each computer are realized. Therefore, when each computer stores table definition information related to table data held by other computers in a table register in the same way as the table definition information of that computer, and queries are made from that computer, a database management system is necessary. A method is used to realize the so-called location transparency range, which does not make the user aware of the location of the table, by determining from the above table registry whether the table exists in the computer or exists in another computer. . However, no particular consideration is given to the case where the size of the computer is not sufficient to have the above-mentioned register.

[Problem to be solved by the invention]

The above conventional technique is an effective method when computer resources, such as large-scale computers, are relatively abundant.

However, computer resources such as personal computers and workstations, which are rapidly becoming popular these days, may have extremely limited computer resources, and it is difficult to store all the table definition information on the host computer in the workstation's table directory. This is because it is difficult to achieve the lance bear range.

There was a problem in that it placed a heavy burden on database users. Also, if all the table definition information on the host computer is stored in the workstation's table directory,
This has the disadvantage that the capacity of the table register increases.

Furthermore, when changing the table registration side, such as adding or deleting a table, it is necessary to change the related table register in order to maintain the integrity between tables, which has the disadvantage of increasing communication volume and reducing performance. Ta.

An object of the present invention is to realize a location translation range without having a table register for all tables when making an inquiry about table data from a workstation connected to a host computer.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a distributed database system composed of a host computer and a plurality of workstations (WS), in which a database management system of the workstations is used as a register for managing tables existing in the workstations. , a query analysis unit, a global procedure creation unit that generates a procedure including a table inquiry command for the database management system of the host computer when a table that does not exist in the query analysis result register is detected, and a procedure created by the global procedure creation unit. It consists of a global procedure execution unit that controls the execution of a group of table query commands.
A workstation that is requested to query table data determines whether the query request includes a request for a table that does not exist on the workstation while processing the query request, and if the request includes a table that does not exist, , is characterized in that it generates and executes a new set of query commands that directly issue a query request to the host computer.

[Effect]

In the above method of the present invention, when a database inquiry command is input from a workstation user or an application program, the inquiry analysis section of the database management system on the workstation side analyzes the inquiry command and searches the tables existing on the workstation. A comparison check is performed using the ``1'' list, and if all the files exist on the workstation, normal query processing against the local database is executed.

On the other hand, if the query command contains a table name other than the table that exists in the directory of the workstation,
The global procedure creation unit decomposes a given query command and generates a global query procedure consisting of a group of query commands for accessing a local database and a group of query commands for accessing a database on the host side. The global procedure execution unit sends an inquiry request to the database management system of the workstation and host using the generated global inquiry procedure, and returns the desired inquiry result. There are several alternatives to the above global procedure. For example, if the query command includes a table that exists on the workstation side, the table will also be transferred to the host computer.
Query processing is executed by the host computer, and the query results are transferred to the workstation. Another method is to generate a search command for a table that does not exist on the workstation, send it to the host computer, and obtain the query result by operating the table data transferred from the host computer on the workstation. It is the role of the optimization mechanism to select one of these multiple methods.Using the method described above, it is possible to realize location transparency range without having a table registry of the host computer on the workstation side. can.

〔Example〕

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

FIG. 1 is a diagram showing an example of a system configuration to which the present invention is applied, and FIG. 2 is a diagram showing the configuration of a workstation database management system according to the present invention.

FIG. 1 is a diagram showing an example of a system configuration to which the present invention is applied. In FIG. 1, 1 is a host computer, 2 is a workstation, 3 is a display, 4 is a communication line, 5 is a database management system on the host computer side, 6
is a database, 7 is a table registry, 8 is a database management system on the workstation side, and 9 is a database.

10 is table climbing 8? # is shown. A host computer 1 and a workstation 2 are connected by a communication line 4. A database management system 5 on the host computer side manages a database 6 and a table registry 7. It also provides services for inquiries from workstations via the communication line 4. The database 6 stores table data on the host computer side. The table register 7 manages definition information of table data stored on the host computer side. The database management system 8 on the workstation side is a database 9.
It also manages 5 ILOs and 4 communication lines.
The service is requested from the host computer 1 via the host computer 1. A database 9 stores table data on the workstation side. The table management book 10 manages definition information of table data stored on the workstation side.

FIG. 2 is a diagram showing the functional configuration of the database management system 8 on the workstation side of the present invention. In FIG. 2, 20 is an overall control function, 21 is a query input/output function, 22 is a query analysis function, 23 is a local database access procedure creation function, 24 is a local database access procedure execution function, and 25 is a global database access procedure creation function. , 26 indicates a global database access procedure execution function, and 27 indicates a data transfer management function.

In the above configuration, when a database inquiry command is input from the display 3 of the workstation or an application program, the inquiry input/output function 21 of the database management system 8 receives the inquiry command and passes it to the inquiry analysis function 22. The query analysis function 22 analyzes the query command, performs a check against the table registration 19, and determines whether the table included in the query exists on the workstation.

In the case that all query commands exist in the workstation, the local database access procedure creation function 23 creates an optimal table access procedure for the database 10, and the local database access procedure execution function 24 executes the procedure and executes the query. Result is,
It is returned to the application program or display through the inquiry input/output function 21. On the other hand, if the 5-query analysis function 22 performs a comparison check with the table uMI9 and determines that the query command includes a request for a table other than the table existing on the workstation, the global database access procedure creation function 25 Creating a global query procedure from the original query command 1 For example, if the query command includes table A that exists on the workstation 8 and table B that does not exist, the table data of table A is transferred to the host computer 1. The database management system 5 on the sending host computer side generates a procedure for performing a join operation between tables A and B and sending the results back to the workstation 2. Alternatively, a procedure is created in which the host computer 1 is requested to transfer table B and the database management system of the workstation 2 performs a join operation between the table data of table B and table A sent to the workstation. The global database access procedure execution function 26 requests the local database access procedure creation function 23 or the data transfer management function 27 to perform processing according to the global database access procedure. The data transfer management function 27 performs transfer processing of inquiry commands, messages, table data, etc. between the host computer 1 and workstation 2 shown above via the communication line 4. The overall control function 20 controls the execution of the functions described above. The functions of the global access procedure creation function 25 will be explained in detail below using the example shown in FIG. In FIG. 3, 30 is an inquiry request command;
9 is the workstation table register, 31LL
- An example of global access procedure commands generated by the global access procedure creation function. Assume that table A exists on the workstation side and table B exists on the host computer side, as in the previous example. Inquiry request command 3o uses column a of table A and table B.
A search is requested for column a of table A, which has the same value as column b of table A. When the inquiry request command 30 is analyzed by the inquiry analysis function 22, it is found that table B does not exist in the register 9. In response to this result, the global access procedure creation function 25 creates a global access procedure 32. The procedure 32 registers table B' in the workstation directory a).

A query command for searching table B of the host is transferred to the database management system of the host b), and the query results transferred from the host are stored in table B' registered in (a) C).

After that, execute a query using table A and table B' (d), and finally delete table B' from the register (e
) generates a series of query commands. By executing this procedure by the global access execution function 26, the initial inquiry request is executed.

According to this embodiment, even if the table registry 9 of the workstation 2 does not contain the contents of the table registry 6 on the host computer side, queries can be made without being aware of the location of the table. can be realized. As a result, the system can be simplified. Furthermore, since no complicated negotiation is required between the host computer and the workstation, the number of communications can be reduced.

〔Effect of the invention〕

As explained above, according to the present invention, an inquiry can be made without being aware of the location of a table even if the workstation table registry does not have table definition information on the host computer side, thereby realizing location transparency range. Can be done. As a result, the system can be simplified. Furthermore, since no complicated negotiation is required between the host computer and the workstation, the number of communications can be reduced. In addition, the space required for the workstation table directory is reduced and
It is possible to eliminate the amount of communication required to update the table registry that occurs when table definition information is changed.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a system configuration to which the present invention is applied, FIG. 2 is a functional configuration diagram of a database management system according to an embodiment of the present invention, and FIG. 3 is an example of global database access procedure generation according to the present invention. It is a figure showing an example. [Explanation of symbols] 1...Host computer 2...
・・・・・・・・・・・・ Workstation 5.8
・・・・・・・・・Database management system 6.9・
......Table register 7.10...
Database 20... Inquiry input/output 22...
......Inquiry analysis 23...
...Local database access procedure creation 24...Local database access procedure execution 25...Global database access procedure creation 26... ......Global database access procedure execution 27... Data transfer management 30...
......Inquiry request command example 32...
......Global database access procedure generation example Y group I2

Claims (1)

[Claims] 1. In a distributed database system consisting of a host computer and multiple workstations, the database system of the workstation is divided into a register that manages tables existing on the workstations, a query analysis section, and a query analysis result register. A global procedure creation unit that generates a procedure including a table inquiry command for the database system management system of the host computer when a non-existing table is detected, and a global procedure that controls the execution of the table inquiry commands generated by the global procedure creation unit. In a workstation that is requested to query table data, the database management system of the workstation is configured to include an execution unit, a register for managing tables existing in the workstation, a query analysis unit, and a query analysis result register. A global procedure creation unit that generates a procedure including a table inquiry command for the database management system of the host computer when a table that does not exist in the host computer is detected, and a global procedure that controls the execution of a group of table inquiry commands generated by the global procedure creation unit. A workstation that is requested to query table data determines whether or not a request for a table that does not exist on the workstation is included during processing of the query request, and determines whether or not the workstation includes a request for a table that does not exist. In this case, by generating a new set of query commands that directly issue query requests to the host computer and executing them, data queries against the distributed database can be performed without retaining the table definition information of the host computer on the workstation side. A query processing method for a distributed database management system characterized by realizing the following.