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From Øystein Grøvlen <Oystein.Grov...@Sun.COM>
Subject Re: Derby I/O issues during checkpointing
Date Mon, 27 Mar 2006 19:23:29 GMT
Raymond Raymond wrote:
> Dear Oystein,
>  In one of you former mails, you said:
> 
>> From: Oystein.Grovlen@Sun.COM (Øystein Grøvlen)

>>    During checkpoint when I/O is slow this creates long queques of
>>    readers.  In my run with 20 clients, I observed read requests that
>>    took more than 20 seconds ......
> 
> 
> I am coding on autimatic checkpoint and incremental checkpoint as
> what we discussed before, I finished party of them and trying to
> do some test on it. I am really interested in how you observed :
> 
>>    I have observed single write
>>    operations that took almost 12 seconds ......
> 
> and
> 
>>    readers.  In my run with 20 clients, I observed read requests that
>>    took more than 20 seconds ......
> 

I ran a variant of the TPC-B benchmark with a large database (20 GB) and 
  a large page cache (1 GB).  I do not think you need TPC-B transactions 
to see this, but I think you need update-intensive transactions that 
frequently needs to load pages from disk.  For example, single record 
updates where an index is used to locate the record.  You will also need 
several connections in parallel (e.g., 20).

--
Øystein

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