[erlang-questions] mnesia_leveldb + prefix keys

Matthias Rieber ml-erlang@REDACTED
Tue Jan 22 11:32:06 CET 2019


I've a question regarding the prefix keys in mnesia_eleveldb. I have a 
record like this:

-record(key, {
  jid       :: { binary(), binary() },
  timestamp :: erlang:timestamp()

-record(table, {
  key = key{},
  payload :: term()

As far as I understand these queries are fast:

  #table{key=#key{jid={<<"user1">>, <<"localhost">>},
                  timestamp = '_'},

Since the keys are ordered I expected that query to be fast:

mnesia:select(table, ets:fun2ms(
 fun(#table{key=#key{jid={<<"user1">>, <<"localhost">>},
                     timestamp = Timstamp},
            payload=P}) when Timstamp > {1,2,3} -> P

But performance tests show that this will read all records (probably only 
the ones with the matching jid). Is it possible to select this in an 
efficient manner?

Best regards,

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