Hello,
We're using the automaton package as part of Elasticsearch for doing regexp
queries. Our business requires us to process rather complex regular
expressions, for example (we have more complex examples, but this one
illustrates the problem):
(¦.)*(¦?[^¦]){1,10}ab(¦.)*(¦?[^¦]){1,10}c(¦.)*(¦?[^¦]){1,10}d
With a large enough value of maxDeterminizedStates, this works. The problem
we're having is that the conversion of this regular expression to a
CompiledAutomaton takes very long. Almost all of the time goes into
determining the common suffix for the Automaton (which is "d" in this example)
- calculated with a call to Operations.getCommonSuffixBytesRef.
If my understanding is correct, this suffix is only used as an optimization (is
this correct?). Skipping the calculation of this suffix allows us to process
these kinds of queries.
So here are my questions:
- Would it be possible to introduce a way to skip the calculation of this
common suffix (ideally something we control from within our query to
Elasticsearch)?
- Or would it be possible to take a look at this getCommonSuffixBytesRef
operation, to see if it can be optimized? Most of the time goes to
determinizing the reversed automaton - maybe this can be avoided somehow?
- Does anyone have any other suggestions? We've tried to reduce the complexity
of the query, but it is something we would really like to support.
Thanks,
Thomas Poppe
