If 1GB would make solr go out of memory by using a filter query cache, then it would have already happened during the initial upload of the solr documents. Imagine the amount of memory you need for one billion documents.. A filter cache would be the least of your problems. 1GB is small in comparison to the entire solr index.
> On 17 Feb 2020, at 10:13, Hongxu Ma <inte...@outlook.com> wrote: > > Hi > I want to know the internal of solr filter cache, especially its memory usage. > > I googled some pages: > https://teaspoon-consulting.com/articles/solr-cache-tuning.html > https://lucene.472066.n3.nabble.com/Solr-Filter-Cache-Size-td4120912.html > (Erick Erickson's answer) > > All of them said its structure is: fq => a bitmap (total doc number bits), > but I think it's not so simple, reason: > Given total doc number is 1 billion, each filter cache entry will use nearly > 1GB(1000000000/8 bit), it's too big and very easy to make solr OOM (I have a > 1 billion doc cluster, looks it works well) > > And I also checked solr node, but cannot find the details (only saw using > DocSets structure) > > So far, I guess: > > * degenerate into an doc id array/list when the bitmap is sparse > * using some compressed bitmap, e.g. roaring bitmaps > > which one is correct? or another answer, thanks you very much! >
