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From Jakob Braeuchi <jbraeu...@gmx.ch>
Subject Re: RsIterator - performance issue
Date Sat, 24 Jul 2004 19:58:31 GMT
hi armin,

the overhead for non-cached objects is imo not a big issue when compared with 
the better performance for cached objects.

+1 for this patch

jakob

Armin Waibel schrieb:

> Hi all,
> 
> I'm wondering about some lines in RsIterator#getObjectFromResultSet() 
> method when query objects.
> 
> In line 428 always the whole result set row was mapped to an internal 
> map, independent from a match in the cache. Why not map the PK values 
> first from the result set, then check against the cache and only if not 
> found in cache we map the whole row from the result set.
> 
> I locally change this behavior and all tests pass, additionally I wrote 
> a simple performance test:
> First time the query read from the DB (no cached objects), second time 
> the objects can be found in cache.
> 
> against MaxDB             new  old
> Time query 10000 objects: 762  752 [ms]
> Time fetch 10000 objects: 161  472 [ms]
> 
> against hsql              new  old
> Time query 10000 objects: 600  556 [ms]
> Time fetch 10000 objects: 250  354 [ms]
> 
> The first read of the new implementation is a bit slower, because when 
> the object was not found in cache the whole result set row was read 
> again (with all PK values). A more performant solution will be to read 
> the non-PK fields only, instead of all fields. But therefor we have to 
> change the RowReader interface.
> 
> Any objections against the patched RsIterator version?
> 
> regards,
> Armin
> 
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