[erlang-questions] Re: Conceptual questions on key-value databases for RDBMs users

Scott Lystig Fritchie <>
Mon Nov 8 23:29:34 CET 2010


I've a couple of comments, joining the thread late, sorry.

Regarding the labels of "key-value database" vs. "document-oriented
database", I typically think of KV DBs as considering their value blobs
to be opaque and doc-oriented DBs as understanding all (or at least
part) of the structure of their values.

    * Hibari is KV
    * Riak is both (the lower parts of the KV store treat blobs as
      opaque, but both the map-reduce KV framework and the new Riak
      Search app can parse the value blobs as JSON, Erlang terms, or
      whatever a Search text analyzer decides to parse)
    * CouchDB and MongoDB are doc-oriented

Joe Armstrong <> wrote:

ja> Does anybody know of any pure-erlang add-ons to ets/dets that do
ja> full-text indexing?  the tricky but seems to be word extraction and
ja> not making/sorting/building the index also building an incremental
ja> index might be difficult (I haven't done this)

Not that I'm aware of.

In the Riak Search app, IIRC, text analysis (and stemming, etc.) can be
done in Erlang or Java.  The inverted indexes managed at each node are
pure Erlang (specifically the merge_index app, see apps/merge_index/src
subdir).  Replication of the merge_index indexes are managed by the
riak_core application.

    https://github.com/basho/riak_search
    https://github.com/basho/riak_core

-Scott


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