Re: implementing a database log

On 2008-04-29, David BL <davidbl@xxxxxxxxxxxx> wrote:

....
Ok so it relates to check pointing. I don't see how these markers are
particularly useful - ie to determine where to start replaying the log
during recovery. For example, when ARIES performs a check point it
records
1) the active transaction list
2) last LSN (Log Sequence Number) for each active transaction
3) the set of dirty pages.
4) for each dirty page, the LSN of the earliest log
record whose effect is not reflected in the page on disk.

This allows the recovery scan to determine where to start replaying
the log (in the REDO pass).


No, I think it's about being able to recover what happened between the
last completed checkpoint and the end of the log.

E.
.