JPH10312385A - Database system, information retrieval method, and recording medium - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a DB system capable of automatically changing a database (DB) to be searched and performing continuous search processing. SOLUTION: A search request (a search condition expression, a lower limit value of an acquired record, a designated DB) from a user is received through an interface module 10 and a search management module 20 is received.
Is recorded in the continuation execution reference table 221. The search management module 20 issues a search command (command) corresponding to the search request to the corresponding DB module 301 to 30n to perform the search processing, and the number of records of the search result becomes the acquired record in the continuous execution reference table 221. When the number is less than the lower limit, the unsearched DB is detected, the designated DB is automatically changed to the unsearched DB, and the search is continuously executed by the search condition expression. The unsearched DB is detected based on the search status table 222, and the search status table 222 is updated each time the search processing is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information retrieval method for efficiently retrieving desired information from a plurality of DBs, for example, as in a distributed database (hereinafter simply referred to as a DB) system.

[0002]

2. Description of the Related Art A plurality of DBs each storing unique information.
As a form of managing the database, a distributed DB system is known. In this type of DB system, a system is constructed for the purpose of physically distributing and arranging DBs on a computer network including a plurality of DBs each storing unique information and sharing data. Is being done. When searching for desired information in such a DB system, first, a DB to be searched is specified, and a search process is performed on the specified DB using a predetermined search condition expression. In this case, any one of the following methods is adopted as the method of designating the DB. The first method is a method in which a user specifies a DB for each search process,
The second method is a method in which the system automatically selects a DB based on the set values of system parameters and the like.

[0003] An outline of the prior art will be described below with reference to FIGS. 7 to 10. FIG. 7 shows a DB adopting the first method.
It is a block diagram of a system. This distributed DB system 2
Comprises an interface module 10 serving as an input / output interface with a user, a plurality of DB modules 301 to 30n, and a search execution module 40. Each module is formed by a computer device reading and executing a predetermined program.
The DB modules 301 to 30n have search processing units 311 to 31n and DBs 321 to 32n respectively storing records each storing unique information, and are based on a search command (command) from the search execution module 40. Search and output the corresponding record. Note that a plurality of D
Reference numeral 30 denotes an unspecified one of the B modules 301 to 30n, and reference numeral 31 denotes a search processing unit 311 to 31n.
The DBs 321-32n will be described with reference numeral 32.

A search execution module 40 issues a search command (command) to a corresponding DB module 30 based on a search request received through the interface module 10, and issues a search command (command) to the DB module 30 by issuing the search command. And a result integration unit 42 that integrates the search results obtained in the above.

FIG. 9 is an explanatory diagram of a procedure of a search process in the DB system 2. First, a search request from a user, that is, a search condition expression for specifying a record to be searched for and a designation (DB name) of the DB 32 to be searched are received through the interface module 10 (step S201). This search request is input to the search command unit 41 of the search execution module 40, and the specified DB3
2 is passed to the DB module 30 including The DB module 30 that has received the search command searches the DB 32 through the search processing unit 31 for a record that satisfies the search condition expression, and returns the search result to the search execution module 40 (Step S202). The search execution module 40 integrates the search results in the result integration unit 42 (step S20).
3), and present it to the user through the interface module 10 (step S204). When a search result that is satisfactory for the user is obtained, the search processing ends (step S205, Yes). On the other hand, if a satisfactory search result is not obtained, the process returns to step S201, and the search request is received again from the interface module 10 (step S205: No).

FIG. 8 is a configuration diagram of a DB system adopting the second system, and the same components as those shown in FIG. 7 are denoted by the same reference numerals. The distributed DB system 3 includes an interface module 10, a DB selection execution module 50, and a plurality of DB modules 30. The DB selection execution module 50 includes: a DB selection unit 51 that specifies a DB to be searched based on system parameter setting values and the like;
It has a search command unit 52 that issues a search request to a corresponding DB module 30 based on a search request received through the module 10, and a result integration unit 53 that integrates search results obtained from the DB module 30.

FIG. 10 is an explanatory diagram of a procedure of a search process in the DB system 3. First, a search request from a user, that is, a search condition expression for specifying a record to be searched is received through the interface module 10 (step S301). This search request is input to the DB selection execution module 50. The DB selection execution module 50 searches the DB3 to be searched by the DB selection unit 51.
2 (step S302), and a search command is issued from the search command unit 52 to the specified DB module 30. DB module 3 that received the search command
0 searches the DB 32 for a record that satisfies the search condition expression through the search processing unit 31 (step S303), and passes the search result to the DB selection execution module 50. DB
The selection execution module 50 integrates the search results in the result integration unit 53 (step S304), and presents the search results to the user through the interface module 10 (step S305). If a search result that is satisfactory for the user is obtained, the process ends (step S306, Yes).
s). On the other hand, if a satisfactory search result is not obtained (step S306: No), re-designation of the search target DB is received from the user through the interface module 10 (step S307), and the process returns to step S303 to perform the designation. The search processing of the corrected DB is performed.

FIG. 6 shows an example of the contents of the search state table 222 in the case where the number of search result records in the DB 3 is 20. FIG.
In the results of the above, the search results are described in L. G
ravano, H .; Garcia-Molina, A .;
"The Effectiveness of GIOSS by Thomas
for the Text Database Discovery Problem ”(Pr
oc. of ACM SIGMOD, pp. 126-1
37, 1994).

[0009]

However, each of the above methods has the following problems. That is, in the first method, when a search result satisfying the user is not obtained, another DB 32 is designated again as a search target DB, and the input of the search request and the search process are repeatedly repeated many times. It had to be complicated.
Further, since the user needs to store the history information of the searched DB 32, the burden on the user is large.

In the second method, since the DB 32 corresponding to the user's search request is specified based on the set values of the system parameters, the probability that the user obtains a satisfactory search result is the first. Although it is higher than the method, the setting process requires time since parameters and the like must be strictly set. In addition, when it is desired to obtain a satisfactory search result by a single search request from a user, the DB system must perform a search process for all DBs, which increases the load on the system.

SUMMARY OF THE INVENTION An object of the present invention is to provide an improved DB which does not require storing history information of a searched DB and can obtain a required search result by a single search request from a user. It is to provide a system. Another object of the present invention is to provide an information search method using the above DB system and a recording medium for realizing the DB system with a general-purpose computer device.

[0012]

According to the present invention, there is provided a DB system for solving the above-mentioned problems, comprising: a plurality of DB modules for searching records from a corresponding DB based on a predetermined search command; Search condition expression, uniquely set lower limit of the number of acquired records, and search target D
B. Upon receiving a search request including the designation of B, a search command based on the search condition expression is sent to the D corresponding to the search target DB.
A search management module having means for issuing a corresponding record by issuing to the B module and comparing the total number of obtained records with the lower limit to determine whether to continue issuing the search instruction; It comprises.

The search management module has, for example, a search status table in which search flags having different status values are obtained for each DB module when the search request is not yet searched and when the search is completed. If the total number is less than the lower limit value, an unsearched DB is specified by referring to the search state table, the search target DB is changed to the specified unsearched DB, and a search instruction based on the search condition expression is issued. It is configured to Further, when the total number of records becomes larger than the lower limit of the number of acquired records, the issuance of the search instruction is terminated.

[0014] Further, an information retrieval method for solving the above-mentioned other problems includes a retrieval condition formula for acquiring a required record from a plurality of DBs in which records are stored, and a lower limit value of a uniquely set number of acquired records. , And a search request including the designation of a search target DB is received from the outside, and all records that satisfy the search condition expression are searched from the search target DB specified by the search request, and obtained by the search. Comparing the total number of records with the lower limit value, and when the total number of records is less than the lower limit value, changes the search target DB to an unsearched DB and continuously executes the search by the search condition expression. On the other hand, when the total number of records is larger than the lower limit, the search based on the search condition expression is terminated.

Further, a recording medium according to the present invention for solving the above-mentioned other problems has a retrieval condition formula for acquiring a required record from a plurality of databases, a lower limit of the number of acquired records uniquely set, a retrieval target database, Receiving a search request including the first name, searching for all records that satisfy the search condition expression from the search target database specified in the search request, and the total number of records obtained by the search and the lower limit value; And, if the total number of records is less than the lower limit, detect an unsearched database, change the search target database name to an unsearched database name, and continuously execute a search using the search condition expression On the other hand, when the total number of acquired records is larger than the lower limit, a process of ending the search based on the search request , And recorded in a form readable is the computer system a program for causing a computer to execute the device.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a functional block diagram showing an embodiment of a DB system according to the present invention. In FIG. 1, the same components as those in the conventional system shown in FIGS. 7 and 8 are denoted by the same reference numerals.

The DB system 1 of this embodiment includes an interface module 10, a search management module 20,
And a plurality of DB modules 30. Each of the modules 10, 20, 30 is formed by a computer device reading and executing a predetermined program. The above-mentioned program is usually stored and used in a storage means built in the computer device, but is stored in a recording medium, such as a CD-ROM, which is dealt with separately from the computer device. May be read and installed in the storage means. Further, the DB module 30 may be formed by a program different from the interface module 10 and the search management module 20.

In the DB system 1 of the present embodiment, as a search request received from a user, a search condition formula for obtaining a required record, a lower limit value of the number of obtained records uniquely set, and a search target DB Use the one that includes the specification.

The search management module 20 includes a search execution unit 2
1 and a continuous execution control unit 22. Search execution unit 2
1 is a DB selection unit 21 for automatically specifying a search target DB
1. A search command unit 212 that issues a search command based on the above search condition expression, and a result integration unit 213 that integrates and temporarily stores the contents of records as search results, while the continuous execution control unit 22 It is configured to include a continuation execution reference table 221, a search state table 222, and a continuation execution determination unit 223 that determines whether to continue the search process. The search execution unit 21 and the continuous execution control unit 22 can exchange data with each other.

The continuation execution reference table 221 is a table for storing a search request received from a user, and is configured to be referred to at any time when determining whether or not to continue execution. The contents are as illustrated in FIG. 3, and a search condition expression for specifying a record to be searched, a lower limit value of the number of acquired records, and a designated search target DB name are stored in an updatable manner. The lower limit value and the search target DB name may be determined in advance based on the set values of the system parameters, and the input from the user may be omitted. In this case, the set values of the system parameters are stored in the continuous execution reference table 221.
Set to be the default information of.

The search state table 222 is a table for temporarily storing a search flag for distinguishing a search state or a non-search state of the DB 30 and the number of records of a search result when the search processing is completed. And unsearched DB
It is configured so that it can be referred to at any time at the time of specifying. As will be described later, the storage information of the search state table 222 is updated whenever the search processing is completed. In this embodiment, a plurality of DBs 30 and the search management module 20 will be described as being directly connected. However, both may be connected by a communication line or the like and physically distributed and arranged in a remote place or the like. Good. In this case, an existing technique can be used for processing related to communication control and the like.

Hereinafter, the operation of the DB system 1 according to the present embodiment will be specifically described with reference to FIG. First, a search request is received from a user through the interface module 10 (step S101). This search request is transferred to the search management module 20. Search management module 2
0 indicates that the continuation execution control unit 21 creates the continuation execution reference table 221 and the search state table 222
Is initialized (step S102). The search management module 20 also stores the search target DB name in the DB selection unit 2.
11 and the search condition formula and search target DB
The name is input to the search command unit 212 of the search execution unit 21. The search command unit 212 creates a search command based on the input search condition expression and search target DB name, and
It is issued to the DB module 30 including B32 (step S103). The DB module 30 executes a search process based on a search command issued from the search command unit 212. Specifically, the search processing unit 31 searches the DB 32 and returns a corresponding record to the search management module 20 (step S104). The search management module 20 that has received the search result determines whether or not to continue the search process (steps S105 and S106).

The determination of continuous execution by the search management module 20 is performed as follows. First, the continuation execution determination unit 223 compares the total number of records as search results with the lower limit in the continuation execution reference table 221. As a result of the comparison, if the total number of records is larger than the lower limit (step S106, No), the record search from the DB module 30 ends. On the other hand, if the total number of records is less than the lower limit (step S106, Yes), a DB in an unsearched state is detected from the search state table 221 and the search target DB name is changed to the detected DB (step S106). S107). At this time, the continuation execution control unit 22 notifies the search execution unit 21 of the continuation execution. Processing is step S
Returning to 103, the changed search target DB and step 1
In step 01, the search processing is continuously executed based on the search condition expression received. This is repeated until the total number of records exceeds the lower limit. When the record search is completed, the record contents are integrated by the search result integration unit 213 (step S108), and this is presented to the user through the interface module 10 (step S109).

Next, the process of changing the contents of the search state table 222 in the above-described series of search processing will be described with reference to FIGS.
This will be described with reference to FIG. In this description, it is assumed that the lower limit value is set to 30. FIG. 4 is a diagram showing an initialization state. When a search request is input to the search management module 20 through the interface module 10, the continuous execution control unit 22 executes the search state table 222.
, The search flags of all the DBs registered in the DB are updated to the unsearched state, and the number of all records of each DB is updated to “0”. This processing is performed in step S1.
01 to S102. Search target DB1 and DB2 are specified, and steps S103 to S10
FIG. 5 shows a change in the contents of the search state table 222 when the corresponding record is obtained from the DB module 30 by the process of FIG. That is, the continuous execution control unit 22
Updates the search flags of DB1 and DB2 in the search state table 222 to the search state, and every time a record as a search result is obtained, the total number of records for DB1 and DB2 corresponding to 10 and 5 respectively Update as follows. In this case, the total number of records is 15, which is smaller than the lower limit (30). The search process is continuously executed based on the conditional expression.

FIG. 6 is a diagram showing a change in the search state table 222 when the search process for the unsearched DB 3 is continuously executed. In the example of FIG. 6, the search result for DB3 is 20, and the total number of records is 35, which is larger than the lower limit (30). Therefore, the search management module 20 executes the subsequent search processing continuously. The search process ends without performing the search. At this time, the search management module 20
Notifies the user via the interface module 10 that the user has acquired more records than the set lower limit. Then, if necessary, an integrated version of the contents of all records is presented.

As described above, the DB system 1 of the present embodiment
Then, when acquiring records matching the search conditions from the plurality of DB modules 30, if the required number of records cannot be obtained only with the previously designated DB, the search management module 20 automatically designates an unsearched DB. Then, the search process is continuously executed under the above search conditions, so that it is not necessary to set a search request and re-execute the search process as in the conventional system, thereby enabling a quick search process. . In addition, since it becomes easy to comprehensively perform the search processing of the plurality of DB modules 30, for example, the search capability when a distributed DB system is constructed can be significantly improved compared to the related art.

[0027]

As is apparent from the above description, according to the present invention, the search target D is satisfied until the user's request is satisfied.
Since B is automatically changed and the search process is repeated,
The user can obtain a desired search result only by inputting a single search request, and the load on the system is reduced. In addition, since it is not necessary to store the history information of the DB for which the search has been completed, there is also an effect that the burden on the user is greatly reduced.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of a DB (database) system according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a procedure of a search process in the DB system according to the embodiment.

FIG. 3 is an explanatory diagram showing an example of the contents of a continuous execution reference table according to the embodiment;

FIG. 4 is an explanatory diagram showing a content example (initialized state) of a search state table according to the embodiment;

FIG. 5 is an explanatory diagram showing a change example of a search state table.

FIG. 6 is an explanatory diagram showing a change example of a search state table.

FIG. 7 is a functional block diagram of a conventional DB system.

FIG. 8 is a functional block diagram of another conventional DB system.

FIG. 9 is an explanatory diagram of a procedure of a search process in the DB system shown in FIG. 7;

FIG. 10 is an explanatory diagram of a procedure of a search process in the DB system shown in FIG. 8;

[Explanation of symbols]

 Reference Signs List 1 DB (database) system 10 interface module 20 search management module 21 search execution unit 22 continuation execution control unit 211 DB selection unit 212 search command unit 213 result integration unit 221 continuation execution reference table 222 search state table 223 continuation execution determination unit 30 , 301 to 30n DB module 31, 311 to 31n Search processing unit 32, 321 to 32n DB (database)

Claims (6)

[Claims] 1. A plurality of database modules for retrieving records from a corresponding database based on a predetermined retrieval command, a retrieval condition expression for retrieving a required record, and a uniquely set lower limit of the number of retrieved records And a search request including the designation of a search target database is received, and a search command based on the search condition expression is issued to a database module corresponding to the search target database to obtain a corresponding record. A search management module having means for comparing the total number of records with the lower limit to determine whether to continue issuing the search instruction. 2. The search management module according to claim 1, wherein the search management module has a search status table in which search flags each having a different status value when the search request is not yet searched and when the search is completed are stored for each database module. When the total number is less than the lower limit value, an unsearched database is specified by referring to the search state table, the search target database is changed to the specified unsearched database, and a search command based on the search condition expression is issued. 2. The database system according to claim 1, wherein the database system is configured to issue. 3. The database according to claim 1, wherein the search management module terminates issuing the search command when the total number of records becomes greater than a lower limit of the number of acquired records. system. 4. A search condition expression for acquiring a required record from a plurality of databases in which records are stored, a uniquely set lower limit of the number of acquired records, and
A search request including the specification of a search target database is externally received, and all records that satisfy the search condition expression are searched from the search target database specified by the search request, and the total number of records obtained by the search is Comparing the lower limit value with the lower limit value, and when the total number of records is less than the lower limit value, changes the search target database to an unsearched database and continuously executes the search by the search condition expression. An information retrieval method in the database system, wherein when the total number of records is larger than the lower limit, the retrieval by the retrieval condition expression is terminated. 5. A search flag having a different status value for each search request when the search is not performed and when the search is completed is recorded for each database, and based on the status value of the search flag, the unsearched database is stored. 5. The information retrieval method according to claim 4, wherein the information retrieval is specified. 6. A process for receiving a search request including a search condition expression for obtaining required records from a plurality of databases, a lower limit value of the number of uniquely obtained records, and a search target database name; A process of searching all records that satisfy the search condition expression from the search target database specified in the search request and comparing the total number of records obtained by the search with the lower limit; If the number is less than the number of unacquired databases is detected and the search target database is changed to an unsearched database and the search is continuously executed by the search condition expression, while the total number of acquired records is greater than the lower limit value Is a process for terminating a search based on the search request, and a program for causing a computer device to execute A recording medium recorded in a form readable by the computer device.