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From Kristian Waagan <kristwaa.apa...@gmail.com>
Subject Re: Is there any debug logging available when a database is being recovered
Date Sat, 23 Apr 2016 20:21:38 GMT
Den 20.04.2016 16.46, skrev Bergquist, Brett:
> It took longer (and never finished) to process the recovery logs file that it did to
restore the database from the previous night from backup (that took 6 hours to "untar")  
At about 14 hours, the recovery log files were not finished processing so we had to give up
and restore from backup.   That seems quite an inordinate amount of time to process the recovery
log files.    Note that this was not an underpowered machine either.   It was an Oracle M5000
with 32 processors, 128G of memory, and Fibre Channel attached storage.
> 
> I would like to start looking at this, so if anyone has any ideas where to begin, shout
them out.

Hi Brett,

>From what I can see, there is some logging available in debug builds
using the LogTrace-flag. I have no recollection of using it, so I cannot
say how useful the information you get from enabling it is.

To try it, get the debug build and specify "derby.debug.true=LogTrace".
Based on a quick scan of the code, without verifying anything, it looks
like you should see when Derby switches to the next log file. There is
also a log entry for the end of the redo phase.

Obtaining the stack trace at various point might also give some clues if
you're willing to dive into the code :)

I expect this part of the code is singlethreaded, so I hope the machine
can give you decent performance using a single logical CPU. Do you
suspect CPU or IO to be a bottleneck?


Regards,
-- 
Kristian

> 
> -----Original Message-----
> From: Bryan Pendleton [mailto:bpendleton.derby@gmail.com]
> Sent: Wednesday, April 20, 2016 5:53 AM
> To: derby-dev@db.apache.org
> Subject: Re: Is there any debug logging available when a database is being recovered
> 
>> So what would be useful would be something like:
>>
>> Performing database recovery
>> Starting analysis pass
>> 215 transactions detected to be processed Starting redo pass ....
>> anything that could give some feedback Starting undo pass ....anything
>> that could give some feedback
>>
> 
> I'm afraid all I can add is: yes, I completely agree, that would be extremely useful.
> 
> bryan
> 
> 
> 
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