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Scala disk card

I have a large card that won't fit in memory, and so I want it to be on disk. I have the following options:

  • Use a pure Java library like MapDB : This works, but I don't get Scala sugar collections like getOrElseUpdate

    and ++=

    , and apply

    / update

    . I could create my own wrapper class around MapDB

    in Scala, but I really don't want to manually apply all the traits Map

    .
  • Use something like redis / memcached: I couldn't find a good Scala library that gave me the traits Map

    for redis or memcached. This might be the best performance solution, but it introduces db startup complexity

So, is there any good Scala library that implements the Scala collection sagars for maps and yet it comes back to disk and / or keystore for large maps?

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2 answers


Chronicle Map is worth mentioning : it is basically the same as MapDB (hard drive implementation ConcurrentMap

), but much more efficient than MapDB.

Example:



val cache: mutable.Map[String, java.util.List[String]] = ChronicleMap
    .of(classOf[String], classOf[java.util.List])
    .averageKey("key")
    .averageValue(...)
    .valueMarshaller(ListMarshaller.of(
        CharSequenceBytesReader.INSTANCE,
        CharSequenceBytesWriter.INSTANCE
    ))
    .entries(...)
    .createPersistedTo(file)
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Answered my own question



import collection.mutable
import org.mapdb.DBMaker
import collection.JavaConversions._

val cache: mutable.Map[String, Seq[String]] = DBMaker.newTempHashMap[String, Seq[String]]()
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