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Posted to derby-dev@db.apache.org by Raymond Raymond <ra...@hotmail.com> on 2006/03/23 15:43:27 UTC

What difference between containCache and pageCache?

I found these two kinds of cache manager in the source
code. I am not sure what difference between containerCache
and pageCache?

Thanks.

Raymond

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Re: What difference between containCache and pageCache?

Posted by Suresh Thalamati <su...@gmail.com>.

Container cache is used to keep track of the open containers 
(table/indexes). An item in this cache is considered is dirty , if 
the container header is modified or a dirty page from the cache is 
written to the container file.

At checkpoint, page cache cleaning make sure all dirty pages in the 
page cache are written to the disk and the container cache cleaning 
will write the header and sync the container file if it is a dirty 
container.

Thanks
-suresh



Raymond Raymond wrote:
> Thanks for your answer. I am looking at the code about checkpoint.
> I found, in checkpoint, both of containerCache and pageCache will
> dump dirty pages. As your answer, does it mean the dirty pages in
> containerCache indicate updates on tables or indexes, and the dirty
> pages in pageCache indicate updates on rows? Am I right?
> 
> Thanks.
> 
> Raymond
> 
> 
>> From: Bryan Pendleton <bp...@amberpoint.com>
>>
>> Raymond Raymond wrote:
>>
>>> I found these two kinds of cache manager in the source
>>> code. I am not sure what difference between containerCache
>>> and pageCache?
>>
>>
>> A container is an aggregate object like a table or an index.
>>
>> A page is a hunk of bytes inside a container, used for storing rows.
>>
>> Does that help?
>>
>> thanks,
>>
>> bryan
>>
> 
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Re: What difference between containCache and pageCache?

Posted by Raymond Raymond <ra...@hotmail.com>.

Thanks for your answer. I am looking at the code about checkpoint.
I found, in checkpoint, both of containerCache and pageCache will
dump dirty pages. As your answer, does it mean the dirty pages in
containerCache indicate updates on tables or indexes, and the dirty
pages in pageCache indicate updates on rows? Am I right?

Thanks.

Raymond

>From: Bryan Pendleton <bp...@amberpoint.com>
>
>Raymond Raymond wrote:
>>I found these two kinds of cache manager in the source
>>code. I am not sure what difference between containerCache
>>and pageCache?
>
>A container is an aggregate object like a table or an index.
>
>A page is a hunk of bytes inside a container, used for storing rows.
>
>Does that help?
>
>thanks,
>
>bryan
>

_________________________________________________________________
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to offer. 
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 MSNŽ Premium right now and get the 
first two months FREE*.

Re: What difference between containCache and pageCache?

Posted by Bryan Pendleton <bp...@amberpoint.com>.

Raymond Raymond wrote:
> I found these two kinds of cache manager in the source
> code. I am not sure what difference between containerCache
> and pageCache?

A container is an aggregate object like a table or an index.

A page is a hunk of bytes inside a container, used for storing rows.

Does that help?

thanks,

bryan