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This table is used to represent information about dirty buffer
pages during normal processing. It is also used during restart
recovery.It is implemented using hashing or via the deferred-
writes queue mechanism. Each entry in the table consists of 2
fields :
- PageID and
- RecLSN
During normal processing , when a non-dirty page is being fixed
in the buffers with the intention to modify , the buffer manager
records in the buffer pool (BP) dirty-pages table , as RecLSN , the
current end-of-log LSN , which will be the LSN of the next log
record to be written. The value of RecLSN indicates from what point
in the log there may be updates. Whenever pages are written
back to nonvolatile storage , the corresponding entries in the
BP dirty-page table are removed. The contents of this table are
included in the checkpoint record that is written during normal
processing. The restart dirty-pages table is initialized from the
latest checkpoint's record and is modified during the analysis
of the other records during the analysis pass. The minimum RecLSN
value in the table gives the starting point for the redo pass during
restart recovery.
Vinay V
Mon Apr 12 18:36:08 IST 1999