System for memory management during run formation for external sorting in database system
First Claim
1. A method of managing a workspace of predetermined fixed extent containing a plurality of variable length records to enable the writing of additional variable length records into said workspace, comprising the steps of:
- performing a limited search for free space in said workspace that is suitable for a next variable length record;
selectively restructuring the available space in said workspace to create suitable free space for said next variable length record if the limited search does not locate a suitable free space for said next variable length record; and
removing some number of records from said workspace to create suitable free space for said next variable length record if the selective restructuring does not create a suitable free space for said next variable length record.
2 Assignments
0 Petitions
Accused Products
Abstract
The memory management system is operational in a database system and functions to gracefully transition data from the allocated memory space to run files on disk only as needed. The memory management system accommodates variable length input records in the workspace of a database sort operation, requires no extra copying of records in memory, and maintains memory utilization at a high level. This memory management system therefore minimizes the amount of data written to disk during run formation and enables the use of the replacement selection algorithm even with variable length input records, which improves performance of sorting and overall operational efficiency of the database system.
62 Citations
33 Claims
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1. A method of managing a workspace of predetermined fixed extent containing a plurality of variable length records to enable the writing of additional variable length records into said workspace, comprising the steps of:
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performing a limited search for free space in said workspace that is suitable for a next variable length record; selectively restructuring the available space in said workspace to create suitable free space for said next variable length record if the limited search does not locate a suitable free space for said next variable length record; and removing some number of records from said workspace to create suitable free space for said next variable length record if the selective restructuring does not create a suitable free space for said next variable length record. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of managing a workspace of predetermined fixed extent to create free space therein to enable the writing of variable length records into said workspace, comprising the steps of:
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populating said workspace with a plurality of variable length records obtained from a set of variable length records, until said workspace is substantially filled; receiving a next one of said set of variable length records; and selectively removing at least one of said plurality of variable length records from said workspace to create free space to accommodate said next one of said set of variable length records. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 24, 25, 26, 27, 28, 29, 30)
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23. A computer-readable medium having computer-executable instructions for performing steps comprising:
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populating a workspace with a plurality of variable length records obtained from a set of variable length records, until said workspace is substantially filled; receiving a next one of said set of variable length records; and selectively removing at least one of said plurality of variable length records from said workspace to create free space in said workspace to accommodate said next one of said set of variable length records. - View Dependent Claims (31, 32, 33)
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Specification