JPH10187742A - Data base dissimilarity canceling retrieval device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make respective data bases freely retrievable in the expression forms of respective users themselves, by translating an inquiry sentence to the inquiry sentence suitable for each data base using a translation function. SOLUTION: In the environment where plural data bases 9 exist, data items having the same meaning but making the expressions respectively different for the data bases are retrieved while canceling the difference in their expressions. The expression form (domain) of value for the data item in the data base is managed, the domains having the same meaning are defined as a domain group, and a global domain to be used as a standard representative in this domain group is selected. At the time of retrieval, when the local domain of data base 9 is different from the global domain, the function of translation between domains is called from a translation function library 4, the inquiry sentence of user is translated to the inquiry sentence suitable for each data base by using this function, and the data base 9 is constructed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a database heterogeneity resolving and retrieving apparatus for retrieving data items having the same meaning in an environment in which a plurality of databases exist, but having different expressions depending on the databases by resolving the difference in the expressions. About.

[0002]

2. Description of the Related Art Companies have introduced and used many database systems for various tasks such as customer management and sales management. Initially, the database was used for simple data management purposes, such as recording, changing, and using customer and sales information. It is required to use a database to obtain management strategic information such as.

For such purposes, there is a case where information from one database alone is not enough. For example, information from a plurality of databases is integrated and used, such as combining customer information and sales information. There is a need. However, since each database is operated independently, information of the same content may be represented in different expression formats. When integrating information from multiple databases, it is necessary to eliminate the differences.

Hitherto, a multi-database has been researched and developed as a mechanism for integrating and using a plurality of databases. A multi-database system is a system that allows users to search distributed databases without being aware of the expression format or structure of individual information by predefining the virtual structure of the database used by the user called the global schema. It is.

[0005] However, in this method, the user can view data only in the form of the global schema, and is forced to take one view.

[0006]

In the conventional system,
In order to define a global schema, it was necessary to know the representation of data in all databases. However, it requires access to the contents of all databases, which is actually very difficult. Therefore, there is a need for a mechanism that can eliminate the difference in data expression without knowing as much as possible the expression format other than the database that the user has.

[0007] Further, there is a demand that a user wants to obtain information of another database in the same expression format as that of his own database. This is because you want to use the data of another database using the application you are using, but that application is created in accordance with the representation format of your database. If this request is to be realized by an existing multi-database, it is necessary to define a global schema having the same format as that of the user's database for each user, which is inefficient.
Therefore, it is necessary to eliminate differences in data representation by defining data differences fragmentarily without defining a global schema. Then, a mechanism that allows the user to easily change the expression format desired by the user is required.

[0008] The present invention has been made in view of the above,
The aim is to provide a database heterogeneity resolving search device that can freely search each database in the expression form of each user even if the expression of data items by each database is different despite the same meaning. To provide.

[0009]

In order to achieve the above object, according to the present invention, data items having the same meaning in an environment where a plurality of databases exist, but having different expressions depending on the databases are represented. A database heterogeneity resolving search device that performs a search by resolving the difference between a database and a local domain management table that manages each domain as a local domain, which is a data representation format of data items of each database, as a local domain management table. Manages each domain as a domain group, and manages a domain group management table for selecting and managing a global domain that is typically used as a representative in each domain group, and a conversion function for converting between domains. Conversion function management table and user input A database in which search data of the searched query is stored and a local domain corresponding to the search data are searched from the local domain management table, and a global domain is extracted from the domain group including the local domain in the domain group management table. And a conversion function search means for searching the conversion function management table for a conversion function for converting the local domain into a global domain when the local domain and the global domain searched by the domain search means are different. Using the conversion function searched by the conversion function search means, translating the query sentence into a query sentence adapted to each database, and searching means for searching each database with the translated query sentence. And it is required to.

According to the first aspect of the present invention, a database storing search data of an inquiry sentence input by a user and a local domain corresponding to the search data are searched from a local domain management table. A global domain is searched from the domain group management table from the domain group including the local domain, and if the searched local domain is different from the global domain, a conversion function for converting the local domain to the global domain is searched from the conversion function management table. Searching, using this conversion function, translating a query sentence from the user into a query sentence adapted to each database, and searching each database with the translated query sentence, a table of search data in each database. Format can be different from the representation of the user's own free to search.

The present invention described in claim 2 is the same as the claim 1.
In the invention described above, when the conversion function search unit cannot search for a conversion function that directly converts the local domain to the global domain, the conversion function search unit searches for a combination of a plurality of conversion functions that can convert the local domain to the global domain. It is the gist to have.

According to the second aspect of the present invention, when a conversion function for directly converting a local domain to a global domain cannot be searched for, the local domain can be converted to the global domain by combining a plurality of conversion functions. .

[0013]

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

FIG. 1 is a block diagram showing the configuration of a database heterogeneity resolving and searching apparatus according to an embodiment of the present invention. The database heterogeneity resolution search device of the present embodiment
Searches for data items that have the same meaning in an environment where multiple databases exist, but have different expressions depending on the database by resolving the difference in the expression. Domain group having the same meaning as a domain group, and selecting a global domain that is typically used as a representative from this domain group, and when searching, the local domain and the global domain of the database are different. In this case, a conversion function between domains is called, a query sentence of a user is translated into a query sentence adapted to each database using the conversion function, and a database is searched using the translated query sentence. The resolution search device is shown in FIG. A syntax analyzer 1 for analyzing the syntax of a query sentence 13 input from the user's application program 12, a query processing controller 2 for controlling the overall flow of processing for the query, and a query converter for converting the query. A query processing unit 11 including a unit 3, a conversion function library 4 as a group of functions for performing data conversion between drains, and a data processing unit 6 for converting a domain of searched data; and a database for accessing the distributed database. An access unit 5, a metadata storage unit 7 that stores and manages information such as a domain and a domain group, information of a table included in a database, and metadata that performs input conversion of the metadata into the metadata storage unit 7 Management unit 8
The database access unit 5 is connected to a plurality of database systems each including a database 9 and a database management system 10 for managing the database 9. The database 9 is also called a local database.

The database heterogeneity resolving and retrieving apparatus of the present embodiment configured as described above has a two-stage process of a preparation phase for preparing a domain definition and the like before executing a search and a search phase for performing an actual search. Is carried out.

First, the preparation phase will be described. In this preparation phase, domains are defined. The concept of domain management in the present embodiment will be described with reference to FIG. For example, as shown in FIG. 2, as a domain representing a data value of a data item in a database, a domain representing a blood type may be represented by a blood type value, represented by a blood type code, or represented by blood type details. There are various expression methods, such as the case of expressing with. In this way, the same meaning among various expressions is defined as a domain group, and only one domain is set as a domain visible to the user, thereby providing a single perspective to the user. can do. In FIG. 2, the date is also listed as a domain group, and in this, year / month / day or month. Day. The year and the like indicate various domains. Further, in FIG. 2, the user uses a blood type code and year / month / day, and these are user domains.

For the domain, the following four settings are required: setting of a local domain, setting of a domain group, creation of a conversion function, and setting of a user domain. Set information such as. These pieces of information are stored in the metadata storage unit 7. 3 and 4 show the configuration of a table of each information stored in the metadata storage unit 7. FIG. The setting of each domain will be described.

(1) Setting of local domain: For the item of the local database 9, a "domain" which is a concept representing the expression form is set. This is called a local domain. For example, for a data item "name" of a database (type is char (20)), its domain is Name
Set to. The meaning of the domain of Name represents not only the type of char (20), but also the form of more detailed expression of "name". For example, this Name: First name first, last name last.・ The space between the first and last name is a space.

The expression format is as follows. The definition of a domain for a column is held in a “column” table as shown in FIG.

Basically, this operation is performed by an administrator of the local database. At this time, the already defined domain is referenced using the metadata management unit 8. If a domain that can be used as a domain for data items in your database is already defined, use it and do not create a new domain.

(2) Setting of a domain group: A group of domains that have different expressions but actually have the same meaning is called a domain group. The domains that fall into this group are all different representations of the same meaning. In this apparatus, all the domains included in this domain group appear to be unified into one domain from the user.

The administrator of the local database determines which domain group the domain that he / she has defined belongs to, and performs a process of entering the domain group. If no suitable domain group is found, create a new domain group. If the domain is already defined, you do not need to set it because it is included in any domain group. FIG. 3B shows a domain group.

In the domain group, one representative domain used as a standard is set (this setting is basically performed by the administrator of the apparatus). The domain is called a global domain. FIG. 3C shows the global domain.

(3) Creation of a conversion function: This is not necessary if a conversion function has already been defined. Create a conversion function between the global domain and the local domain using a general programming language. Compile your function into a form that can be dynamically linked.

The relationship between the conversion function and the domain is registered using the metadata management unit 8. The correspondence between the conversion function and the domain and the location of the conversion function are held in a “conversion function” table as shown in FIG.

The conversion function creates a bidirectional function such as global domain → local domain, local domain → global domain. However, depending on the conversion, it may not be possible to create a function in both directions (for example, in the name conversion, the conversion "Gengo Suzuki" → "Gengo Suzuki" = the removal of blanks is possible, but the reverse is true). Generally not possible). In that case, create a function in only one direction. The reason for creating a bidirectional function is to perform conversion by combining functions when there is no function to directly convert.

(4) Setting of user domain: A domain that is actually visible to the user is selected from the domain group (for each user). This is called a user domain.
When a user makes an inquiry to the present apparatus, even if there are items expressed by various domains, all items are unified by the user domain. Further, by changing the user domain, it is possible to change the appearance of data from the user. FIG. 3D shows a user domain.

Next, the search phase will be described. A search is performed using the domain information as follows. The user generally calls and uses the functions of the apparatus from an application program in the form of a library or the like. The inquiry from the user is created in the SQL language which is a search language of the relational database.

(1) Determination of the query DB: The query is analyzed by the syntax analysis unit 1, and a database including tables and columns included in the query is known by searching the “column” table of the metadata storage unit 7.

(2) Retrieval of the domain of the column included in the query: FIG. 3 shows the domain of the column included in the query.
It is known by searching the "column" table shown in FIG.

(3) Search for user domain: By searching the "domain group user" table shown in FIG. 3D from the inquiring user and domain,
Search for a user domain.

(4) Search for a conversion function: A conversion function between the user domain and the domain of (2) is checked by using a "conversion function" table shown in FIG. If a conversion function directly applicable to A → B is not found, a search is made to see if conversion is possible in combination with A → C, C → B. This is a search problem on a graph in which a domain is a node and the existence of a transformation function between domains is an edge, and can be easily realized using an algorithm studied in graph theory.

(5) Translation and execution of query: There are two implementation methods depending on the system used for the database access unit 5. The database access unit 5 uses middleware for database integration.

Implementation method 1 is a case where the database access unit 5 allows an extensible database-like function.

A database management system capable of extending functions using a function defined by a user is called an extensible database management system (extensible DBMS).
If a corresponding function can be used for the database access unit, the conversion function can be realized as a user-defined function of the extensible DBMS. The function can then be used in the query language.

In order to create a query to be passed to the database access unit, a column included in a sentence of a user query is replaced with a form including a conversion function.

[0037] In the form If the domain of the column to be searched and the column of the conditional expression are different from the user domain, the following replacement is performed.

A) Replace (search column) with (local domain → user domain conversion function) ((search column)). B) Replace (the column included in the conditional expression) with (the conversion function from the local domain to the user domain) ((the column included in the conditional expression)).

The realization method 2 is a case where the database access unit 5 has only the function of the relational database. Middleware that can access the database only with the same function as the relational database cannot use the user-defined function in the query language like the extensible database, so the conversion is realized by rewriting the query as in the realization method 1. Can not. It is necessary to realize data conversion as follows.

Conversion of the value included in the inquiry: The value included in the inquiry is converted from the user domain to the local domain. Conversion of search result: The data processing unit 6 converts the value of the search result from the local domain to the user domain.

In each of the methods, a plurality of databases are accessed, and the result is a sum of search results of the respective databases.

Next, two examples of the case where the synthesis conversion is performed and the case where the synthesis conversion is not performed will be specifically described. FIG. 5 shows a sample database (DB) used. For metadata such as domains, the values in FIGS. 3 and 4 follow this example. The same database is used in both Example 1 and Example 2. The two examples are common up to the definition of the conversion function in the preparation phase. The destination is different from the setting of the user domain. The two databases (DB) are in the following format.

[0043] That is, the "name" of DB1 does not leave a space between the surname and the name, and the "name" of DB2 places a half-width space between the surname and the name. The blood type of DB1 is represented by a code, and DB2
Are represented by values.

First, as an example 1, a case where no synthesis conversion is performed will be described. In the preparation phase of Example 1, the definition of the local domain, the domain group, the conversion function, and the determination of the user domain are performed as described above, respectively, as described above.

(1) Definition of local domain: DB1,
The administrator of DB2 sets the local domain for each DB column. Since the domain of the name of DB1 has no space between the first and last names, it is set to NameNoSpace. Since the blood type domain of DB1 is represented by a code, it is set as BloodTypeCode. Since the domain of the name of DB2 has a space between the first and last names, it is set to NameSpace.
Since the blood type domain of DB2 is represented by a half-width value, it is set as BloodTypeValue.

(2) Definition of domain group: Here, as a domain group: Name (The domain included is NameNoSpace, NameSpac
e, global domain is NameNoSpace), BloodType (included domain is BloodTypeCode,
BloodTypeValue, BloodTypeValueLarge, and the global domain, BloodTypeValueLarge) are set. Here, BloodTypeValueLarge is a domain in which a value is entered in double-byte characters (A, B, O, AB).

[0047] (4) Determination of user domain: In this example, it is assumed that the user domain is equal to the global domain (FIG. 3D)
Is used by the user gsuzuki in That is, And

Next, the search phase of Example 1 will be described. Convert the user's inquiry into an SQL sentence as follows. Inquiry: select name where blood type = “A” (1) Search for table including blood type and name: Search “column” table to find DB1 and DB2.

[0049] Hereinafter, (4) and later will be described separately for the realization method 1 and the realization method 2 described above.

The case of the realization method 1 will be described. (6) Query execution: The search results for each DB are as follows. DB1: Miki Suzuki DB2: Koki Machihara The final search result is the sum of the results, and the result is Miki Suzuki, Koki Machihara.

Next, the case of the realization method 2 will be described. (6) Translate the inquiry.

DB1: select name where blood type = “0” DB2: select name where blood type = “A” Becomes

Next, as a second example, a case in which synthesis conversion is performed will be described. Consider a situation where a user who uses DB1 wants to obtain information in the format of DB1. At this time, the user domain is of the DB1 type (this is a case where the user satoh in FIG. 3 uses it).

First, the preparation phase will be described.
The process up to (3) is the same as in Example 1, so (4) is performed as follows.

(4) Determination of user domain: The user domain of Name is set to NameNoSpace. The BloodType user domain is BloodTypeCode. Next, the search phase of Example 2 will be described. The user's inquiry is changed to an SQL statement as follows.

[0056]

As described above, according to the present invention,
A database storing search data of a query sent from a user and a local domain corresponding to the search data are searched from a local domain management table, and a global group is managed from a domain group including the local domain. When the searched local domain and the global domain are different from each other, a conversion function for converting the local domain into the global domain is searched from the conversion function management table, and an inquiry sent from the user is performed using the conversion function. Is translated into a query suitable for each database, and each database is searched using the translated query. Therefore, even if the expression format of the search data in each database is different from the user's own expression format, The searches freely the data in they want representation format can be easily obtained, it is possible to use the data in the database more freely. In addition, there is no need to define a global schema, and it is possible to eliminate the difference in expression format.

Further, in the existing multi-database, the difference in the expression format cannot be eliminated unless the expression format in all the databases is known, whereas in the present invention, the administrator of the local database has his own. It is only necessary to be aware of the local domain, which is a representation format in the database, and the global domain, which is a standard representation format, and it is not necessary to be aware of how it is represented in other databases.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a database heterogeneity resolving and searching device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the concept of domain management.

FIG. 3 is a column table stored in a metadata storage unit used in the database heterogeneity resolving and searching device of FIG. 1;
FIG. 3 is a diagram illustrating a configuration of a domain table, a domain group table, and a domain group user table.

FIG. 4 is a diagram showing a configuration of a conversion function table stored in a metadata storage unit used in the database heterogeneity resolving and searching device of FIG. 1;

FIG. 5 is a diagram showing a sample database.

FIG. 6 is a diagram showing an example of a blood type correspondence table used by a conversion function.

FIG. 7 is an explanatory diagram showing a combination conversion of domains.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Syntax analysis part 2 Query processing control part 3 Query conversion part 4 Conversion function library 5 Database access part 6 Data processing part 7 Metadata storage part 8 Metadata management part 9 Database 10 Database management system

Claims (2)

[Claims] 1. A database heterogeneity resolving search device for retrieving data items having the same meaning in an environment where a plurality of databases exist, but having different expressions depending on the databases, by resolving the difference in the expressions. A local domain management table that manages the domain, which is the data representation format of the data item, as a local domain for each database, and manages each domain that has the same meaning as a domain group and represents a standard within each domain group A domain group management table that selects and manages global domains that are used in common, a conversion function management table that manages conversion functions that convert between domains, and search data of a query sent from a user are stored. Database Domain search means for searching a local domain corresponding to the search data from the local domain management table, and searching for a global domain from the domain group management table from a domain group including the local domain; and When the searched local domain is different from the global domain, a conversion function search unit that searches the conversion function management table for a conversion function that converts the local domain into the global domain; and a conversion function searched by the conversion function search unit. And a search means for translating the query sentence into a query sentence adapted to each database using the translated query sentence and searching each database with the translated query sentence. 2. The method according to claim 1, wherein the conversion function searching means searches for a combination of a plurality of conversion functions capable of converting the local domain into the global domain when the conversion function that directly converts the local domain into the global domain cannot be searched. The database heterogeneity resolving and retrieving apparatus according to claim 1, further comprising: