What will happen if I set a small indices.fielddata.cache.size?


(Andrew Ochsner) #1

Hello:

I have a cluster that's encountering memory pressure. It's predominantly
tuned for write performance (logs). Occasionally we get a query sent in
that sorts the entire dataset by timestamp which explodes our fielddata
cache size. It doesn't lead to OOM errors, but a lot of GC churn so we
have to go in and manually clear the fielddata caches. I want to set the
indices.fielddata.cache.size to something (let's say 30% for the sake of
argument). My question is... what will happen if the size of the fielddata
cache required for that query is more than the 30% I've allocated for the
node? Initial tests seem to indicate that things "just work" (I get a
response that looks valid, the caches are kept in check, etc) but I can't
really validate that the results are properly sorted etc (too much data).

I know we really need more memory and/or more nodes. Just thought I'd ping
the experts if they know for sure what to expect....

Thanks!
Andy O

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(system) #2