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From Aroj George <>
Subject Is reduce not incremental?
Date Sun, 19 Jun 2011 08:10:38 GMT
Hi All,

>From what I have read, Couch does an incremental map the
map-reduce is re-run only if a document in the view has been updated.

>From what I can see from the logs, with level=debug and also by adding a log
statement in the reduce function,
it seems the reduce step is redone every time for the same query even if no
document has been updated!

Yes, the map step is not redone, but I thought the reduce values are cached
in the internal non-leaf nodes?
Why then does Couch rerun the reduce every time for the exact same query (
same group level etc..)

I had a hunch that this may be because Couch caches the reduce values only
for group_level = exact.
But that too didn't show any different behaviour.

So will be glad if someone can help me understand what's going on.
Does Couch "always" run the reduce step? Doesn't it cache the reduce values
in the non-leaf node?
And if so, why does it execute the reduce function again even if there has
not been any document updates?


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