I am trying to do some statistics to estimate recovery speed.
I can get how many log records the recovery process scaned
during the recovery and how long the recovery takes.The recovery
speed I got so far is something like
X log records/second
But, to use the recovery speed to schedule the checkpoint,
I need it likes
X KB/second
I looked into the org.apache.derby.impl.store.raw.log.LogToFile.java .
The checkpoint is trigger in the flush(long fileNumber, long wherePosition)
function. The condition to trigger a checkpoint is :
if ((logWrittenFromLastCheckPoint + potentialLastFlush) > checkpointInterval
&&
checkpointDaemon != null && !checkpointDaemonCalled && !inLogSwitch)
logWrittenFromLastCheckPoint, potentialLastFlush and checkpointInterval
are in size (X bytes), so, I need the revovery speed in size (e.g. X
KB/second).
In another word, I want to know how much (KB) log the recovery process
scaned during recovery. I refered to
http://db.apache.org/derby/papers/logformats.html,
it says the log record wrapper keeps the length of the log record.
I checked the source code and found the length of the log record
is only used in the getNextRecordBackward() and getNextRecordForward()
functions in org.apache.derby.impl.store.raw.log.Scan.java. I can't
get it outside those functions. Anyone can give me some suggestions to
solve the problem?
Thanks.
Raymond
From: Mike Matrigali <[EMAIL PROTECTED]>
I don't know off hand, but you should note that log record
size is most dependent on the size of the data that is affected.
For instance an insert log record will have the part of the row
on that page in that log record.
Raymond Raymond wrote:
Hi, anyone knows how long is a log records in derby?
I need to caculate something like how many log records
are in 1M log. I refered to
http://db.apache.org/derby/papers/logformats.html
but it does not tell me the answer. Anyone happens
to know that?
Thanks.
Raymond
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