Re: Distributed IDF for Solr using ExactStatsCache issue

[thallesr <th...@gmail.com>]

Not exactly your case, but i stumbled upon the same problem.
What i was able to identify was that the problem with different score is
because it uses MaxDocs to calculate score and that one sometimes differ
between replicas.

All the exactStats impl did not solve the problem for me, because they do
solve the problem if the shards have different statistics but not if the
replicas of the same shard have different ones.

One easy way to solve the problem is to change Solr code and exactStats impl
to ask statistics for all replicas from the shards involved (not only one
for each shard) and the calculated score will always be equal, of course it
has a lot of downsides. i did that, but the fact that the whole cluster
would be queried for all searches in my case made it impractical.

I created a script to repeatedly add a random number of docs while
simultaneously deleting some, and after some iterations the MaxDoc got
different between the replicas of the shards, even in  a single instance.
And then checked that none of those impls solved the problem.



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