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From "Kevin Sutter (JIRA)" <>
Subject [jira] Commented: (OPENJPA-407) Cache SQL (or closer precursors to SQL) more aggressively
Date Wed, 17 Oct 2007 19:50:50 GMT


Kevin Sutter commented on OPENJPA-407:

Took a quick look at your patch.  Much more involved than my initial experimentation.  I was
actually looking at it from a Query viewpoint and I was thinking of caching the generated
sql along with the query compilation cache.  That is, if a specific jpql query was cached
after it was parsed and compiled, then couldn't we tag along the cached generated sql.  As
my previous notes on the dev mailing list indicated, we would still have to take into account
the variable aspects of the query (parameters, hints, result size, etc).  So, maybe going
this route would have hit just as many parts.  But, your patch was much more extensive than
I was hoping for.  Guess this shows how tight the sql generation and the "query processing"
really is.

Figuring out where to base the cache was also a question for me.  Like you have found out,
if you do it at too high of a level then we'll hit synchronization issues.  If I put it at
too low of a level, then it turned out to be useless.  I was actually thinking of scoping
the cache to an EntityManager (broker) instance.  Maybe not as useful as across all active
brokers, but we would still gain a sizeable benefit (hopefully).

Those are my initial thoughts.  To be honest, I haven't completely grasped your proposed changes,
so I don't have any specific comments on your changes yet...


> Cache SQL (or closer precursors to SQL) more aggressively
> ---------------------------------------------------------
>                 Key: OPENJPA-407
>                 URL:
>             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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