Publication Details
Title: Reorganization in Persistent Object Stores
Author: R. Salama, L. Wegner, and J. Thamm
Group: ICSI Technical Reports
Date: May 1997
PDF: ftp://ftp.icsi.berkeley.edu/pub/techreports/1997/tr-97-023.pdf
Overview:
The Record Identifier (RID) storage concept was initially made popular through IBM's System R. It remains in use for DEC's Rdb and IBM's DB2 and is attractive because of its self-contained nature. It can even be combined with pointer swizzling. Although simple in principle, its details are tricky and little has been released to the public. One particular problem is the reclamation of empty space when a RID-file becomes sparsely populated. Since RIDs, also called Tuple Identifiers (TIDs), are invariant by definition, pages can be deleted physically, but not logically. Therefore, there must be a mapping from "old" to "new" page numbers. If the self-contained nature is to be preserved, this is not to be achieved by a table but rather through some arithmetical "folding" similar to hashing schemes. Page numbers are meant to collide creating merged pages. The paper explains in detail an efficient division-folding method where f adjacent pages are merged into one Keywords: persistent storage, file reorganizations, pointer swizzling, complex objects
Bibliographic Information:
ICSI Technical Report TR-97-023
Bibliographic Reference:
R. Salama, L. Wegner, and J. Thamm. Reorganization in Persistent Object Stores. ICSI Technical Report TR-97-023, May 1997
Author: R. Salama, L. Wegner, and J. Thamm
Group: ICSI Technical Reports
Date: May 1997
PDF: ftp://ftp.icsi.berkeley.edu/pub/techreports/1997/tr-97-023.pdf
Overview:
The Record Identifier (RID) storage concept was initially made popular through IBM's System R. It remains in use for DEC's Rdb and IBM's DB2 and is attractive because of its self-contained nature. It can even be combined with pointer swizzling. Although simple in principle, its details are tricky and little has been released to the public. One particular problem is the reclamation of empty space when a RID-file becomes sparsely populated. Since RIDs, also called Tuple Identifiers (TIDs), are invariant by definition, pages can be deleted physically, but not logically. Therefore, there must be a mapping from "old" to "new" page numbers. If the self-contained nature is to be preserved, this is not to be achieved by a table but rather through some arithmetical "folding" similar to hashing schemes. Page numbers are meant to collide creating merged pages. The paper explains in detail an efficient division-folding method where f adjacent pages are merged into one Keywords: persistent storage, file reorganizations, pointer swizzling, complex objects
Bibliographic Information:
ICSI Technical Report TR-97-023
Bibliographic Reference:
R. Salama, L. Wegner, and J. Thamm. Reorganization in Persistent Object Stores. ICSI Technical Report TR-97-023, May 1997