TOC:
Lecture 3
Syllabus:
Syllabus
PERSISTENCE --
PERSISTENCE
- SEVERAL APPROACHES TO DELETION:
- EXPLICIT DELETE OPERATION: DANGLING OID PROBLEM
- MARK FOR DELETION - KEEP A REFERENCE COUNT - DO REAL DELETE ONLY WHEN COUNT IS ZERO
- EXPLICIT DELETE OPERATION & FAULT ON DELETED OBJECT: FREELY ALLOW DELETION - REFERENCES TO DELETED OBJECT CAUSE FAULTS
- METHODS & APPLICATIONS NEED PROVIDE FAULT HANDLING CODE
- DELETED OBJECTS' OIDs CANNOT BE REUSED - NOT A PROBLEM
- PROVIDE NO EXPLICIT DELETE OPERATION: PERSISTENT OBJECT IS "GARBAGE COLLECTED" WHEN IT IS NO LONGER REFERENCED
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Ugo O. Gagliardi
GSD-6306 Spring 2003-2004