Data processing system and method with data sharing for the same

Abstract

If relocation of a table with a high reference frequency is made possible, the database management method and system are arranged to improve performance according to the number of increased nodes and accumulate a reference frequency of each external storage unit allocated to each database management node. A data storage area for storing the table with a high reference frequency, located in the external storage unit, is specified as a shared data area to be referenced by plural nodes. The system is controlled to cause the nodes to refer to the shared table stored in the shared data area on any timing in parallel. This prevents load from being concentrated onto the node allocated to the data area.

1 . A database management method for management of a plurality of database management nodes, comprising the steps of: 
 making an access to a table having a data area allocated to each database management node but not to a table having a data area not allocated to each database management node in a shared nothing system in which each of said plurality of database management nodes makes access to a table stored in a data area allocated to each database management node;    calculating access frequencies of said table stored in said data area allocated to each of said plural database management nodes;    determining if one of said access frequencies is greater than or equal to a predetermined value; and    if one of said access frequencies is more than or equal to said predetermined value, re-allocating said table with the access frequency greater than or equal to the predetermined value as a shared table to be referenced by one or more database management nodes to which said table with the access frequency is not allocated, for distributing load of said disk to said plural database management nodes.    
   
   
       2 . The database management method as claimed in  claim 1 , wherein said shared table is updated by the database management node to which said shared table is allocated, and when said shared table is updated, each of all the database management nodes having a capability of referring to said shared table operates to update data stored in a cache located in each node itself.  
   
   
       3 . The database management method as claimed in  claim 1 , wherein one or more tables and shared tables in data areas allocated to said database management nodes respectively are provided in each of said partitioned data areas located on an external storage unit, a cache is allocated to said external storage unit in a manner to correspond with each of said tables and shared tables, and said cache is controlled by the corresponding database management node.  
   
   
       4 . The database management method as claimed in  claim 1 , further comprising steps of monitoring a referring status of each of said tables and shared tables located in said data areas to which said database management nodes are allocated respectively and dynamically switching said table into said shared table or vice versa according to the referring frequency of said table.  
   
   
       5 . A database management system comprising: 
 a plurality of database management nodes; and    an external storage unit having data areas each having a table;    wherein a database management node makes an access to a table having a data area allocated to each database management node but not to a table having a data area not allocated to each database management node in a shared nothing system in which each of said plurality of database management nodes makes access to a table stored in a data area allocated to each database management node;    wherein said database management node calculates access frequencies of said table stored in said data area allocated to each of said plural database management nodes;    wherein said database management node determines if one of said access frequencies is greater than or equal to a predetermined value; and    wherein said database management node, if it is determined that one of said access frequencies is greater than or equal to a predetermined value, re-allocates said table with the access frequency greater than or equal to the predetermined value as a shared table to be referenced by one or more database management nodes to which said table with the access frequency is not allocated, for distributing load of said disk to said plural database management nodes.    
   
   
       6 . The database management system as claimed in  claim 5 , wherein said shared table is updated by the database management node to which said shared table is allocated, and when said shared table is updated, each of all the database management nodes having a capability of referring to said shared table operates to update data stored in a cache located in each node itself.  
   
   
       7 . The database management system as claimed in  claim 5 , wherein one or more tables and shared tables in data areas allocated to said database management nodes respectively are provided in each of said partitioned data areas located on an external storage unit, a cache is allocated to said external storage unit in a manner to correspond with each of said tables and shared tables, and said cache is controlled by the corresponding database management node.  
   
   
       8 . The database management system as claimed in  claim 5 , 
 wherein said database management node monitors a referring status of each of said tables and shared tables located in said data areas to which said database management nodes are allocated respectively and dynamically switching said table into said shared table or vice versa according to the referring frequency of said table.    
   
   
       9 . A database management program for management of a plurality of database management nodes having computer readable codes arranged to function on a database management system, said management program comprising the steps of: 
 making an access to a table having a data area allocated to each database management node but not to a table having a data area not allocated each database management node in a shared nothing system in which each of said plurality of database management nodes makes access to a table stored in a data area allocated to each database management node;    calculating access frequencies of said table stored in said data area allocated to each of said plural database management nodes;    determining if one of said access frequencies is greater than or equal to a predetermined value; and    if one of said access frequencies is more than or equal to said predetermined value, re-allocating said table with the access frequency greater than or equal to the predetermined value as a shared table to be referenced by one or more database management nodes to which said table with the access frequency is not allocated, for distributing load of said disk to said plural database management nodes.    
   
   
       10 . The database management program as claimed in  claim 9 , wherein said shared table is updated by the database management node to which said shared table is allocated, and when said shared table is updated, each of all the database management nodes having a capability of referring to said shared table operates to update data stored in a cache located in each node itself.  
   
   
       11 . The database management program as claimed in  claim 9 , wherein one or more tables and shared tables in data areas allocated to said database management nodes respectively are provided in each of said partitioned data areas located on an external storage unit, a cache is allocated to said external storage unit in a manner to correspond with each of said tables and shared tables, and said cache is controlled by the corresponding database management node.  
   
   
       12 . The database management program as claimed in  claim 9 , further comprising steps of monitoring a referring status of each of said tables and shared tables located in said data areas to which said database management nodes are allocated respectively and dynamically switching said table into said shared table or vice versa according to the referring frequency of said table.