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Elasticsearch: 10,000ft view
- sam_lowry_ 10y ago"Your lucene index must be in memory"… holy crap!
- polyfractal 10y agoThis isn't true, just fyi. Lucene actually relies on the OS' filesystem cache heavily. A Lucene index (e.g. an Elasticsearch shard) is composed of many small "segments". Each segment is an immutable file, which allows the OS to aggressively cache them. But if your index is larger than available memory (very common), the OS will naturally start paging the segments on/off disk as required. That's the root of the "give no more than 50% of your memory to ES" advice, since the other 50% is needed by the OS FS cache for Lucene segments Source: I'm an Elasticsearch dev :)
- pwnedbilly 10y agoThanks for the heads up, not sure where I've picked up that idea - will update accordingly :)
- pwnedbilly 10y agoI've made some changes/clarifications thanks to heads up from two of the Elasticsearch guys. Thanks guys! :)