Use MMapDirectory on a temporary location, Matthias. If you really need in-memory indexes, a new Directory implementation is coming (RAMDirectory will be deprecated, then removed), but the difference compared to MMapDirectory is typically not worth the hassle. See this issue for more discussion.
https://issues.apache.org/jira/browse/LUCENE-8438 Dawid On Tue, Sep 25, 2018 at 10:44 AM Matthias Müller <matthias_muel...@tu-dresden.de> wrote: > > Hi, > > Lucene provides different storage options for in-memory indexes. I > found three structures that would qualify for the task: > > * RamDirectory (which I currently use for prototyping, but wonder if it > is the ideal choice for my task) > * MemoryIndex, which claims to have better performance and resource use > for small documents > * MMapDirectory which should outperform RamDirectory for huge indices > (what is "huge?") > > > My plan is to periodically index some properties (string codes, longs, > lat/lng points) of a larger database content with Lucene for quicker > lookups (compared to slow SQL queries). > > What would be the most efficient (or intended) storage option for such > an index in terms of lookup speed and CPU/memory use? Below [1] is a > brief summary of the index contents and I hope these figures are > sufficient to get a recommendation. But I am also happy to study more > detailed documentation on the matter. > > - Matthias > > [1]: Summary of index contents and intended use > * Total documents: 500.000 - 1.000.000, may grow to 10.000.000 records > in mid future. > * Document fields (all of them single value fields): > * String (9x), usually 1-10 characters long, mostly recurring > values (5% distinct) > * LongPoint (4x), two fields contain mostly distinct values, one > lostly recurring values (5-10% distinct), one field acts as a primary > key > * LatLonPoint (1x), 30% distinct > * Refresh interval: 1..5 minutes (I currently create a fresh index > instance on each update and discard the old one) > * Most queries are range queries and exact matches on several > properties, sometimes I need to retrieve the property fields of a > single document based on a primary key value. > --------------------------------------------------------------------- To unsubscribe, e-mail: java-user-unsubscr...@lucene.apache.org For additional commands, e-mail: java-user-h...@lucene.apache.org
