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From "Raymond Raymond" <raymond_de...@hotmail.com>
Subject Re: Derby I/O issues during checkpointing
Date Mon, 27 Mar 2006 22:47:55 GMT

>From: Øystein Grøvlen <Oystein.Grovlen@Sun.COM>
>
>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

Thanks for your answer. Did you use some tools to know something like
"single write operations that took almost 12 seconds" and "read requests
that took more than 20 seconds". I downloaded TPC-B benchmark program,
it didn't give me those kind of information. I want to know how did you
know the time for reads and writes.^_^.

Thanks.

Raymond

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