Trying to reduce LCR processing in streams to the minimum required

Oracle Streams 10.2 Capture is progressing much more slowly than we think it should at a particular installation.  

We have a simple capture rule defined that *should* only be generating a few thousand LCRs for the few tables to be replicated (ever) and none in the time window processed to produce the data below.  

We are looking at V$STREAMS_CAPTURE and the numbers do not seem to make sense.  

TOTAL_PREFILTER_DISCARDED 260,961

TOTAL_PREFILTER_KEPT                               0

TOTAL_PREFILTER_EVALUATIONS       261,001

TOTAL_MESSAGES_CAPTURED            41,176

TOTAL_MESSAGES_CREATED               44,918

TOTAL_FULL_EVALUATIONS                    3,715

 

I think that "Total Messages Captured" is the total number of redo entries passed to capture, and "Total Messages Created" is the number of LCRs created.  

Based on the prefiltered numbers, everything is decided in prefiltering. So why are any LCRs being created? Why do I create more messages than I capture? And what is the meaning of Full Evaluations?  

 Is there a way to reduce the number of LCRs being created?  

I feel like I've browsed a few hundred manual pages and I'm coming up empty. If someone either has an answer or can point me in the direction of either a Fine Oracle Manual section that covers this or another reference that can get me out of browser search futility, I'd be much obliged.  

I am pretty sure we have already applied the recommended streams performance patches, but if someone has a comprehensive list we can cross reference it with what we have already applied.  

Something just seems very wrong. Even if there is a good reason for pawing through redo after the simple rule has rejected the changes, the rate of processing is abyssmal. I would think it should be able to process millions of LCRs per hour, not dozens. So I'm thinking we're missing something really, really basic.  

Thanks,  

mwf

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