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https://issues.apache.org/jira/browse/OPENJPA-407?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12535776
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Patrick Linskey commented on OPENJPA-407:
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The change was trivial: I changed the 'sql' local variable in
SelectImpl.execute() to be a member variable, and added a null check to control
whether or not to go to the DBDictionary to create a new one.
This depends on the original patch; the original patch lets us cache
SelectImpls. Without that patch, the SQLBuffer would always be uninitialized
anyways.
I don't think that the lack of thread-safety in my prototype is an issue, since
in the worst case, we just end up over-creating SQLBuffers. However, I am
concerned about the fact that I'm ignoring the forUpdate and fetch parameters
that are passed to execute(). I think that it might be ok to ignore fetch,
since I think it's the same as the one that was used to create the SelectImpl,
and is just being passed through for use by the DBDictionary. But I need to
look at that more closely, and also do the same analysis for the forUpdate
statement.
But first I want to reproduce the numbers that I was seeing, to make sure that
this is a worthwhile avenue.
> Cache SQL (or closer precursors to SQL) more aggressively
> ---------------------------------------------------------
>
> Key: OPENJPA-407
> URL: https://issues.apache.org/jira/browse/OPENJPA-407
> Project: OpenJPA
> Issue Type: Improvement
> Components: jdbc, kernel, query, sql
> Affects Versions: 0.9.0, 0.9.6, 0.9.7, 1.0.0
> Reporter: Patrick Linskey
> Fix For: 1.1.0
>
> Attachments: OPENJPA-407.patch
>
>
> When data is not available in the data cache, OpenJPA dynamically creates SQL
> to look up the requested data. OpenJPA should more aggressively cache this
> SQL to accelerate pathways from a cache miss to the database.
> The generated SQL takes a number of factors into account, including the
> requested records, transaction status, currently-loaded data, and the current
> fetch configuration. Any caching would need to account for these factors as
> well.
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