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From Suresh Thalamati <suresh.thalam...@gmail.com>
Subject Re: [jira] Resolved: (DERBY-801) Allow parallel access to data files.
Date Wed, 15 Nov 2006 18:54:10 GMT
Anders Morken (JIRA) wrote:
>      [ http://issues.apache.org/jira/browse/DERBY-801?page=all ]
> 
> Anders Morken resolved DERBY-801.
> ---------------------------------
> 
>     Resolution: Fixed
> 
> OK, I'm marking this one as resolved, then. I've logged DERBY-2086 to remind us to look
into some kind of 
> resource pooling mechanism for encryption buffers and similar.
> I guess this isn't the only place where a pooling mechanism could be useful, 
> so I intentionally worded it in a generic fashion.

> 
> Regarding enhancing the StorageFactory interfaces to support general parallel access,
I'm not sure I 
> understand Suresh's intention completely. Implementing support for concurrent IO is specific
to the 
> different container types - and it may not even be feasible for compressed containers
that require on 
> decompression for seeks. Suresh, maybe you could explain it in a new Jira issue? ;-)
> 
> As I considered earlier, we could enhance the StorageRandomAccessFile interface to add

> getChannel() support, but even that would apply only to random access files backed by
real files 
> that do support getChannel - and we'd have to throw in some JVM-dependent trickery as
well, 
> since getChannel() in RandomAccessFile only exists in Java 1.4+. 
> (What's the timeframe on deprecating 1.3 support? I guess it could be a while? =)
> 

Not sure when I made such a generic statement about storage factory 
parallel access support, sorry if I had confused you.  One thing I 
wanted to work is if some one replaces the storage factory with 
another implementation, new readPage/WritePage you added gets executed 
instead of the old ones that allowed only single read/write of a 
container file at a time.

I think we both are talking the same thing , As you say all that might 
be needed is to add getChannel() method to the StorageRandomAccessFile 
Interface and use it it in the RafContainer4.java instead of checking 
for fileData is an instanceof java.io.RandomAccessFile.


Thanks
-suresh

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