Ok, just to be clear Derby checkpoints are already asynchronous.
The one synchrounous point is that while a page is being written
no update that exact page can be happening.
Updates to all other pages in the
database may be going on concurrently with this operation. So unless
you are worried about concurrency on the single page, I believe
Derby checkpoints already do what you describe.
In the case of Derby the list is the numerical order list of buffers
in the cache, and is always traversed in order. The checkpoint is
done by a background thread asynchronous to other user threads.
Raymond Raymond wrote:
From: Mike Matrigali <[EMAIL PROTECTED]>
Reply-To: "Derby Development" <[email protected]>
Could you define "fuzzy" checkpoint or site what update interference
you are trying to avoid.
Fuzzy checkpointing means checkpoints are asynchronous and occur ant the
same time as new database updates are being made. The general actions
in a fuzzy checkpoint are:
1. Force log buffer to disk from memory.
2. To check if there are any buffer still on the checkpoint list form
the previous checkpoint.
If there are any, then write them out to disk.(the list is supposed
to be empty under
some control).
3. All dirty buffers will be listed in the current checkpoint list.
4. Gather other useful information.
Once these actions have done, the remainder of the checkpoint can also
proceed in
parallel with future database updates. e.t.: a write process will
examine the checkpoint
list periodically, write some of the buffers on the list to disk and
remove thme from the
list.Under some controls, it is supposed that the list will be empty
just befor the next
checkpoint is taken.
Those are just the general processes of fuzzy checkpointing. I think we
can use some
technic to make it works more efficient. That is what I am trying to
do.^_^.
Anyone has some ideas about that?
Raymond
_________________________________________________________________
Scan and help eliminate destructive viruses from your inbound and
outbound e-mail and attachments.
http://join.msn.com/?pgmarket=en-ca&page=byoa/prem&xAPID=1994&DI=1034&SU=http://hotmail.com/enca&HL=Market_MSNIS_Taglines
Start enjoying all the benefits of MSN® Premium right now and get the
first two months FREE*.
