Distributed database management system including logical database constituted by a group of physical databases

• US 6,457,007 B1
• Filed: 08/05/1994
• Issued: 09/24/2002
• Est. Priority Date: 08/05/1993
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Nishiyama, Eisaku, Kikuchi, Satoshi, Ito, Hiromichi, Nakane, Keiichi, Hashimoto, Hisashi
• Primary Examiner(s): Von Buhr, Maria N.
• Application Number:
  US08/285,534
• Time in Patent Office: 2,972 Days
• Field of Search: 395/600, 364/DIG.1, 364/DIG.2, 707/10, 707/100, 707/102, 707/103-R-1
• US Class Current: 1/1
• CPC Class Codes: G06F 16/256 in federated or virtual databases
• CPC Class Codes: G06F 16/27 Replication, distribution or synchronisation of data between databases or within a distributed database system; Distributed database system architectures therefor

Abstract

A distributed database management system includes a communication network, at least a terminal device including an application program execution unit connected to the communication network, a plurality of information processors connected to the communication network, a plurality of physical databases installed in at least one of the information processors, at least a logical database grouping a plurality of the, physical databases, the logical database being defined by logical database information stored in at least one of the terminal device and the plurality of information processors, at least a table stored in at least one of the physical databases, and a table location searching unit installed in at least one of the terminal device and the plurality of information processors, for searching a table stored in at least one of the physical databases based on the logical database information, the table being requested to access on a logical database, from the application program execution unit.

Claims

1. A distributed database management system comprising:

a communication network;

at least a terminal device including application program execution means connected to said communication network;

a plurality of information processors connected to said communication network;

a plurality of physical databases installed in at least one of said information processors;

at least a logical database grouping a plurality of said physical databases, said logical database being defined by logical database information is stored in at least one of said terminal device and said plurality of information processors;

at least a table stored in at least one of said physical databases; and

table location searching means installed in at least one of said terminal device and said plurality of information processors, for searching a table stored in at least one of said physical databases, when said table is requested from said application program execution means, by searching a group of physical databases defined in said logical database information.

2. A distributed database management system according to claim 1, wherein said logical database information includes a priority order of each physical database constituting the logical database;

and

wherein said table location searching means searches for a database stored in the desired table on the physical database on the basis of the priority order of said logical database information.

3. A distributed database management system according to claim 1, wherein said logical database information includes access privilege information for the logical database;

and

wherein said table location searching means checks an access privilege of an application program user instructed from said terminal device prior to access to the logical database.

4. A distributed database management system according to claim 1, wherein said logical database information includes account information for identifying whether to approve said request or not, of the physical database constituting the logical database;

and

wherein said table location searching means logs in the physical database constituting the logical database based on the account information of said logical database information for identifying account information issued from an application program in said terminal device.

5. A distributed database management system according to claim 4, wherein said table location searching means checks the account information received from the application program in said terminal device with the account information of said logical database information prior to access to the logical database.

6. A distributed database management system according to claim 1, wherein said logical database information includes account information for identifying whether to approve said request or not, of the physical database constituting the logical database;

and

wherein said table location searching means logs in the physical database constituting the logical database using account information corresponding to the physical database of said logical database information on the basis of account information issued from an application program in said terminal device.

7. A distributed database management system according to claim 1, wherein said logical database information includes identification information of a physical database constituting the logical database and a password as account information of the physical database.

8. A distributed database management system according to claim 1, wherein a desired database processor (server) is a processor among said plurality of information processors each having a physical database management system and a physical database.

9. A distributed database management system according to claim 1, wherein one of said plurality of information processors is a gateway server located between a plurality of information processors as database servers having said terminal device, a physical database management system, and a physical database, via said network each having distributed database access management means for managing said plurality of database servers.

10. A distributed database management system comprising:

a communication network;

at least a terminal device including application program execution means connected to said communication network;

a plurality of information processors connected to said communication network;

a plurality of physical databases installed in at least one of said information processors;

at least a logical database grouping a plurality of said physical databases and account information for identifying whether to approve an access to at least one of said physical databases, said logical database and said account information being defined by logical database information stored in at least one of said terminal device and said plurality of information processors; and

account information searching means installed in at least one of said terminal device and said plurality of information processors, for searching account information for logging in a physical database constituting said logical database using the account information held in said logical database information, said account information for said logging in being inputted in an access to a logical database, said access being issued from said application program execution means.

11. A distributed database management system according to claim 10, wherein a desired database processor (server) is a processor among said plurality of information processors each having a physical database management system and a physical database.

12. A distributed database management system according to claim 10, wherein one of said plurality of information processors is a gateway server located between a plurality of information processors as database servers having said terminal device, a physical database management system, and a physical database, via said network each having distributed database access management means for managing said plurality of database servers.

13. A distributed database management system which is an information processor which is connected to at least one physical database holding a table via a physical database management system for managing said physical database, and is connected furthermore to application program execution means for accessing said physical database, receiving an access statement for accessing physical databases which is issued by said application program execution means, selecting one of said physical databases as an access object, and transferring said access statement to the physical database management system for managing said physical database, comprising:

a logical database dictionary for holding information on a logical database in which at least one of said physical databases is grouped;

a logical database defining unit for registering information on said logical database in said logical database dictionary;

a statement buffer for holding said access statement;

a logical database access controller for receiving an access statement from said application program execution means and storing it in said statement buffer; and

a table location searching unit for transferring said access statement held in said statement buffer to the physical database management system for managing said physical database by selecting one of said physical databases as an access object;

wherein said table location searching unit includes means for receiving an access statement for instructing logging in the database, for selecting one of said physical databases belonging to the instructed logical database as an access object of said access statement when the database which is instructed to be connected is registered in said logical database dictionary as said logical database, for selecting another one of said physical databases belonging to the instructed logical database as an access object of said access statement when a response of access refusal is given to the transfer of said access statement, and for transferring said access statement held in said statement buffer once again.

14. A distributed database management system according to claim 13, wherein said information on the logical database includes identification information of the logical database, and a priority order of at least one of said physical databases, wherein each identification information of at least one physical database belonging to said logical database;

and

wherein said table location searching unit includes means for deciding an access object of said access statement according to said priority order of at least one of the physical databases included in said information on the logical database held in said logical database dictionary.

15. A distributed database management system according to claim 13, wherein said information on the logical database includes identification information of the logical database, a priority order of said physical databases belonging to the logical database, and identification information of each of said physical databases belonging to the logical database;

and

wherein said table location searching unit includes means for selecting a highest priority physical database as an access object of said access statement according to said priority order of at least one of the physical databases included in said information on the logical database held in said logical database dictionary, when said access statement to be transferred is a statement for instructing creation of tables.

16. A distributed database management system according to claim 13, wherein said information on the logical database includes access privilege information for said logical database;

and

wherein said table location searching unit includes means for checking an access privilege of said application program execution means which issues said access statement using said access privilege information which is held in said logical database dictionary, prior to transfer of said access statement and for refusing transfer of said access statement when there is no access privilege.

17. A distributed database management system according to claim 13, wherein said information on the logical database includes identification information of the logical database, and identification information of each of said physical databases belonging to the logical database;

and

wherein said table location searching unit includes means for rewriting the logical database identification information of said access statement held in the statement buffer, which is to be logged in to decided identification information of the physical database when said access statement to be transferred designates the identification information of the logical database and instructs logging in and for transferring said rewritten access statement to the physical database management system for managing said physical database by selecting said decided physical database as an access object.

18. A distributed database management system according to claim 17, wherein said information of the logical database has at least one logical database account having at least one user identifier and password which are permitted to access said logical database furthermore;

and

wherein said table location searching unit includes means for checking whether the logical database account described in said access statement coincides with one of logical database accounts held in said logical database dictionary prior to transfer of said access statement and for refusing transfer of said statement when there is no coincidence.

19. A distributed database management system according to claim 17, wherein said information of the logical database has a physical database account having a user identifier and password which are permitted to access said physical database according to each identification information of said physical database furthermore;

and

wherein said table location searching unit includes means for rewriting the logical database account of said access statement held in the statement buffer to said physical database account held in said logical database dictionary prior to transfer of said statement furthermore when said access statement to be transferred instructs logging in the database.

20. A distributed database management system according to claim 19, wherein said logical database dictionary has a logical database control block and a logical account control block as a storage area of information on said logical database, and said logical database control block is installed in each said logical database and holds at least the identification information of said logical database and the identification information of at least one physical database belonging to said logical database, and said logical account control block is installed for each said logical database account and holds a physical database account having at least the identification information of said physical database which is permitted to access by said logical database account and the identifier and password of a user who is permitted to access said physical database;

and

wherein said table location searching unit includes means for selecting the physical database indicated by the physical database identification information which is held in said logical database control block holding said logical database identification information and said logical account control block holding said logical account in common as said access object when said logical database identification information and said logical database account are described in said access statement.

21. A distributed database management system according to claim 20, wherein said logical database defining unit includes means for receiving input of said logical database account, encrypting the physical database account included in said information by using said logical database account as a key, and storing it in said logical database dictionary when the information of said logical database is registered in said logical database dictionary;

and

wherein the physical database account rewriting means of said table location searching unit includes means for receiving input of said logical database account, decrypting the encrypted physical database account which is held in said logical database dictionary in correspondence with the identification information of the physical database decided as a transfer object by using said inputted logical database account as a key, and using it so as to rewrite said logical database account.

22. A distributed database management system according to claim 21, wherein said table location searching unit includes means for refusing transfer of said access statement when decryption of the physical database account stored in said logical database dictionary fails.

23. A distributed database management system according to claim 20, wherein said logical database dictionary has a logical account control block for holding at least the identification information of said physical database which is permitted to be accessed by said logical database account and the physical database account of said physical database for each said logical database account as a storage area of said physical database account for information on said logical database, and rewriting of said database account is to rewrite the account of said logical database of the access statement held in said statement buffer to an account corresponding to the physical database identification information which is decided as an access object among the physical database accounts held in said logical account control block which holds said described logical database account when said logical database account is described in said access statement.

24. A distributed database management system according to claim 23, wherein said table location searching unit includes means for transferring said logical database account without rewriting it when said logical account control block holding said described logical database account is not in said logical database dictionary.

25. A distributed database management system according to claim 23, wherein said table location searching unit includes means for transferring the access statement without rewriting said logical database account when the account of the physical database which is decided as an access object is not in said logical account control block which holds said described logical database account furthermore.

26. A distributed database management system according to claim 20, wherein said information of the logical database has a physical database account having a user identifier and password which are permitted to access said physical database according to each identification information of said physical database furthermore;

and

wherein said table location searching unit includes means for rewriting the logical database account of the logical database of said access statement held in the statement buffer to said physical database account held in said logical database dictionary prior to transfer of said statement furthermore when said access statement to be transferred instructs logging in the database.

27. A distributed database management system according to claim 17, wherein said logical database dictionary has a logical database control block for holding at least the identification information of said logical database and the identification information of at least one physical database belonging to said logical database in each said logical database as a storage area of information on said logical database and said table location searching unit rewrites the identification information of said logical database to the identification information of the physical database which is decided as an access object among the physical database identification information held in said logical database control block which holds the identification information of said designated logical database.

28. A distributed database management system according to claim 27, wherein said table location searching unit includes means for transferring said logical database identification information without rewriting it when said logical database control block holding said described logical database identification information is not in said logical database dictionary.

29. A distributed database management system according to claim 13, wherein said table location searching unit includes means for selecting each of at least one physical database belonging to said logical database as an access object, transferring said access statement to the physical database management system for managing said physical databases, creating a table by combining system catalog information of each physical database which is inputted as a response to said transfer into said physical database management system, and informing said application program execution means which issues said access statement of the contents of said table when said access statement to be transferred designates said logical database and instructs to refer to the system catalog.

30. A distributed database management system according to claim 13, wherein the distributed database management system has a log information storage area for holding the log information on access to said logical database in each said logical database furthermore;

and

wherein said table location searching unit includes means for storing the log information on the executed logical database access in said log information storage area, and means for informing of the information held in said log information storage area according to a request from said application program execution means.

31. A distributed database management system according to claim 30, wherein said log information includes at least one of identification information of the logical database, identification information of the physical database, the table identification information, a user identifier of the logical database described in said received access statement, and a user identifier of the physical database described in said transferred access statement which are to be accessed.

32. A distributed database management system according to claim 13, wherein when said access statement includes designation of a table, said table location searching unit includes table location predicting means for predicting said physical database holding said table before transferring said access statement, and selecting said predicted physical database as an access object of said access statement.

33. A distributed database management system according to claim 32, wherein said table location predicting means is means for extracting physical database identification information which is described in said access statement beforehand from said access statement and selecting said physical database indicated by said physical database identification information as an access object.

34. A distributed database management system according to claim 32, wherein the distributed database management system has an access table buffer for associating and holding the identification information of said physical database and the table identification information held in said physical database furthermore;

and

wherein said table location predicting means is means for searching for identification information of the designated table in said access table buffer, detecting the physical database corresponding to said table identification information, and selecting said physical database as an access object, and said table location searching unit includes means for storing the identification information of said physical database which is decided as an access object by transferring the access statement which designates said table and the identification information of said designated table in said access table buffer furthermore.

35. A distributed database management system according to claim 32, wherein the distributed database management system has a system catalog buffer for associating and holding identification information of said logical database, identification information of the physical database belonging to said logical database, and table identification information held in said physical database furthermore;

wherein said table location searching unit includes means for selecting each of at least one physical database belonging to said logical database as an access object, transferring said access statement to the physical database management system for managing said physical databases, creating a table having the identification information of the logical database, the identification information of the physical database belonging to said logical database, and the table identification information held in said physical database by combining the system catalog information of each physical database which is inputted as a response to said transfer into said physical database management system, informing said application program execution means which issues said access statement of the contents of said table, and storing the contents of said table in said system catalog buffer furthermore when said access statement to be transferred designates said logical database and instructs to refer to the system catalog; and

wherein said table location predicting means is means for searching for the identification information of said designated table in said system catalog buffer, detecting the physical database corresponding to the table identification information, and selecting said physical database as an access object.

36. A distributed database management system according to claim 35, wherein the distributed database management system has an access table buffer for associating and holding the identification information of said physical database and the table identification information held in said physical database furthermore;

and

wherein said table location searching unit includes means for storing the identification information of said physical database which is an access object of transfer when the access statement designating said table is transferred and the identification information of said designated table in said access table buffer furthermore.

37. A distributed database management system according to claim 13, wherein said table location searching unit includes means for creating a new access statement for designating each table designated in said access statement one by one and instructing an operation which is the same as that of said access statement on the basis of said access statement when the access statement to be processed which is held in said statement buffer includes designation of a plurality of tables and for selecting each access statement as a processing object of said transfer and means for creating a table by combining a response corresponding to the transfer of each of said new access statements into said physical database management system, and informing said application program execution means which issues said access statements of the contents of said created tables furthermore.

38. A distributed database management system which is an information processor which is connected to at least one physical database holding a table via a physical database management system for managing said physical database, and is connected furthermore to application program execution means for accessing said physical database, receiving an access statement for accessing physical databases which is issued by said application program execution means, selecting one of said physical databases as an access object, and transferring said access statement to the physical database management system for managing said physical database, comprising:

a logical database dictionary for holding information on a logical database in which at least one of said physical databases is grouped;

a logical database defining unit for registering information on said logical database in said logical database dictionary;

a statement buffer for holding said access statement;

a logical database access controller for receiving an access statement from said application program execution means and storing it in said statement buffer; and

a table location searching unit for transferring said access statement held in said statement buffer to the physical database management system for managing said physical database by selecting one of said physical databases as an access object;

wherein said table location searching unit includes means for receiving an access statement for instructing logging in the database, creating an access statement for designating each table designated in said access statement one by one and instructing an operation which is the same as that of said access statement when the access statement to be processed which is held in said statement buffer includes designation of a plurality of tables, selecting one of said physical databases belonging to the designated logical database as said access object, transferring said created access statements respectively, creating a new table by combining responses to said transfer, and informing said application program execution means which issues said access statement of the contents of said created table.

39. A distributed database management method in a system including

a communication network,

at least a terminal device including application program execution means connected to said communication network,

a plurality of information processors connected to said communication network, and

a plurality of physical databases installed in at least one of said information processors,

said method comprising the steps of:

storing logical database information in at least one of said terminal device and said plurality of information processors, said logical database information defining at least a logical database grouping a plurality of said physical databases;

storing tables in at least one of said physical databases;

receiving a request for one of said tables from said application program execution means; and

searching said table for which said request was received by searching a group of physical databases defined in said logical database information.

40. A distributed database management method in a system including

a communication network,

at least a terminal device including application program execution means connected to said communication network,

a plurality of information processors connected to said communication network, and

a plurality of physical databases installed in at least one of said information processors,

said method comprising the steps of:

storing logical database information in at least one of said terminal device and said plurality of information processors, said logical database information defining at least a logical database grouping a plurality of said physical databases, and account information for identifying whether to approve an access to at least one of said physical databases;

receiving an access to a logical database from said application program execution means, account information for logging in a physical database constituting said logical database being inputted in said access; and

searching said account information for logging in using the account information held in said logical database information.

41. A distributed database management method in a system which is an information processor which is connected to at least one physical database holding a table via a physical database management system for managing said physical database, and is connected furthermore to application program execution means for accessing said physical database, receiving an access statement for accessing physical databases which is issued by said application program execution means, selecting one of said physical databases as an access object, and transferring said access statement to the physical database management system for managing said physical database, said method comprising the steps of:

holding in a logical database dictionary, information on the logical database in which at least one of said physical databases is grouped;

registering by a logical database defining unit, information on said logical database in said logical database dictionary;

holding in a statement buffer, said access statement;

receiving through a logical database access controller, an access statement from said application program execution means and storing it in said statement buffer; and

transferring through a table location searching unit, said access statement held in said statement buffer to the physical database management system for managing said physical database by selecting one of said physical databases as an access object;

wherein said table location searching unit includes means for receiving an access statement for instructing logging in the database, for selecting one of said physical databases belonging to the instructed logical database as an access object of said access statement when the database which is instructed to be connected is registered in said logical database dictionary as said logical database, for selecting another one of said physical databases belonging to the instructed logical database as an access object of said access statement when a response of access refusal is given to the transfer of said access statement, and for transferring said access statement held in said statement buffer once again.

42. A distributed database management method in a system which is an information processor which is connected to at least one physical database holding a table via a physical database management system for managing said physical database, and is connected furthermore to application program execution means for accessing said physical database, receiving an access statement for accessing physical databases which is issued by said application program execution means, selecting one of said physical databases as an access object, and transferring said access statement to the physical database management system for managing said physical database, said method comprising the steps of:

holding in a logical database dictionary, information on the logical database in which at least one of said physical databases is grouped;

registering by a logical database defining unit, information on said logical database in said logical database dictionary;

holding in a statement buffer, said access statement;

receiving through a logical database access controller, an access statement from said application program execution means and storing it in said statement buffer; and

transferring through a table location searching unit, said access statement held in said statement buffer to the physical database management system for managing said physical database by selecting one of said physical databases as an access object;

wherein said table location searching unit includes means for receiving an access statement for instructing logging in the database, creating an access statement for designating each table designated in said access statement one by one and instructing an operation which is the same as that of said access statement when the access statement to be processed which is held in said statement buffer includes designation of a plurality of tables, selecting one of said physical databases belonging to the designated logical database as said access object, transferring said created access statements respectively, creating a new table by combining responses to said transfer, and informing said application program execution means which issues said access statement of the contents of said created table.