Browse Prior Art Database

Allocation and Re-Use of Shared Database Control Information

IP.com Disclosure Number: IPCOM000037519D
Original Publication Date: 1989-Mar-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Elliott, LC: AUTHOR [+2]

Abstract

Disclosed is a method of allocating and reusing shared database table control blocks so as to minimize the number of allocation and deallocation operations.

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Allocation and Re-Use of Shared Database Control Information

Disclosed is a method of allocating and reusing shared database table control blocks so as to minimize the number of allocation and deallocation operations.

Table control block structures each contain information needed for operations on a specific table which is shared by all processes concurrently accessing the table. Table control blocks contain the description of the columns in the table and all the indexes on the table. For each table control block, a "usecount" is kept. It is a count of the number of processes which require use of the table control block at that time.

Table control blocks require a significant amount of overhead to establish, since I/O to the table's data file and index file is required. Thus, a method for retaining that information is desirable, even after the usecount becomes zero, since another process may require access to the table.

When the usecount becomes zero, the control block is not deallocated. Instead, it remains in memory, and can be either overwritten when a control block is needed for another table (saving operations to deallocate the old block and allocate the new one) or, if not yet overwritten, can be used if the original table is needed again.

Disclosed anonymously.

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