Method of changing system configuration in shared-nothing database management system

• US 8,041,685 B2
• Filed: 02/27/2008
• Issued: 10/18/2011
• Est. Priority Date: 01/09/2004
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Maciel, Frederico Buchholz, Ito, Daisuke, Fujiwara, Shinji, Ushijima, Kazutomo
• Primary Examiner(s): Lee; Wilson
• Application Number:
  US12/071,827
• Publication Number:
  US 20080163237A1
• Time in Patent Office: 1,329 Days
• Field of Search: 707634-641, 707644-660, 707670-682, 707751-758
• US Class Current: 707/678
• CPC Class Codes: G06F 16/284 Relational databases
• CPC Class Codes: Y10S 707/99932 Access augmentation or optimizing
• CPC Class Codes: Y10S 707/99943 Generating database or data structure, e.g. via user interface

Abstract

A shared-nothing database management system employs a method of adding and removing a database server without significantly affecting the processing performance for accessing a table from a user or an application. A scheduler module creates a schedule which separately handles the addition of a CPU resource and the addition of a storage I/O resource, and a server is added in accordance with the created schedule. A common disk is used to remove a disk at an arbitrary timing. Further, a data region is previously subdivided on the common disk to eliminate a movement of data associated with the addition of a server.

Claims

1. A system configuration changing method in a shared-nothing database management system which comprises a plurality of CPU resources, a storage, and a network for connecting said CPU resources and said storage, wherein each of said plurality of CPU resources runs a database search program stored in a computer-readable storage medium, and each database search program being executable by a processor and functioning as a backend module for processing data, said method comprising the steps of:

allocating physically independent data regions of the storage to respective backend modules by registering mapping information between the data regions and the backend modules;

determining whether or not a CPU resource is to be removed from the shared-nothing database management system by monitoring the states of the plurality of CPU resources;

in response to the determination that the CPU resource is to be removed, delegating a data region of the storage previously allocated to a backend module corresponding to the CPU resource to be removed to another backend module; and

relocating data on the delegated data region of the storage to respective backend modules except the backend module corresponding to the CPU resource to be removed by changing the mapping information.

2. A system configuration changing method in a shared-nothing database management system which comprises a plurality of CPU resources, a storage, and a network for connecting said CPU resources and said storage, wherein each of said plurality of CPU resources runs a database search program stored in a computer-readable storage medium, and each database search program being executable by a processor and functioning as a backend module for processing data, said method comprising the steps of:

allocating physically independent data regions of the storage to respective backend modules by registering mapping information between the data regions and the backend modules;

adding to said shared-nothing database management system a backend module exclusively for sorting and merging data without accessing a table in a database, wherein the added backend module sorts and merges data by receiving the data from other backend modules that have read the data from said storage;

determining whether or not a storage I/O resource is to be added to said backend module exclusively for sorting and merging data; and

in response to the determination that the storage I/O resource is to be added, relocating data to respective backend modules including said added backend module by changing the mapping information.

3. The system configuration changing method according to claim 2, wherein said step of adding a backend module for sorting and merging data comprises activating a program for sorting and merging data on a pooled backend module which is connected to the network and is not functioning as a CPU resource for said shared-nothing database management system.

4. The database management method in a database management system including a plurality of database servers, a plurality of backend modules running on respective of said plurality of servers for processing data of a database, a storage coupled to said plurality of database servers and having a plurality of data regions each of which stores data composing the database, the database management method comprising the steps of:

previously allocating said plurality of data regions to respective backend modules so that each of said plurality of backend modules exclusively access at least two of said data regions,

wherein each of said plurality of backend modules exclusively processes data stored in data regions allocated thereto;

adding to said database management system a new backend module running on a server; and

re-allocating said plurality of data regions to respective backend modules and said new backend module so that each of said plurality of backend modules and said new backend module exclusively access at least one of said data regions,

wherein each of said plurality of backend modules and said new backend module exclusively processes data stored in said at least one of said data regions allocated thereto.

5. The database management method according to claim 4, wherein said adding step comprises a step of adding said new backend server to said database management system as a module exclusively for sorting and merging data without accessing data of said database.

6. The database management method according to claim 5, further comprising a step of:

determining, prior to said re-allocating step, whether or not a storage I/O is to be added to said new backend module,

wherein said step of re-allocating is executed in response to said step of determining.

7. The database management method according to claim 4, wherein said step of previously allocating comprises a step of registering mapping information that indicates a correspondence between each of said plurality of backend modules and said at least two of said plurality of data regions allocated thereto.

8. The database management method according to claim 7, wherein said step of re-allocating comprises a step of changing the mapping information.

9. A database management method in a database management system including a plurality of database servers, a plurality of backend modules running on respective said plurality of servers for processing data of a database, a storage coupled to said plurality of database servers and having a plurality of data regions, each of which stores data comprising the database, the database management method comprising the steps of:

previously allocating said plurality of data regions to respective backend modules so that each of said plurality of backend modules exclusively access at least one of said data regions,

wherein each of said plurality of backend modules exclusively processes data stored in said at least one of said plurality of data regions allocated thereto;

removing a backend module among said plurality of backend modules; and

re-allocating said plurality of data regions to respective backend modules other than removed backend module so that each of said plurality of backend modules other than the removed backend module exclusively access at least one of said data regions,

wherein each of said plurality of backend modules other than said removed backend module exclusively processes data stored in said at least one of said data regions allocated thereto.

10. The database management method according to claim 9, wherein said step of previously allocating comprises a step of registering mapping information that indicates correspondence between each of said plurality of backend modules and said at least one of said plurality of data regions allocated thereto.

11. The database management method according to claim 10, wherein said step of re-allocating comprises a step of changing the mapping information.