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From "Ian Ribas (JIRA)" <>
Subject [jira] [Issue Comment Deleted] (LUCENE-6582) SynonymFilter should generate a correct (or, at least, better) graph
Date Fri, 19 Jun 2015 02:35:01 GMT


Ian Ribas updated LUCENE-6582:
    Comment: was deleted

(was: This comment was written early in my attempts and I'm afraid I didn't review it later.
In the final solution, it is much clearer that the longer terms are not individual synonyms
of the shorter terms, specially since the longest version is what appears first on the output.
I'll have to change the comment, and take away the TODO (it was a marker for things to remember
to ask when submitting).

I don't think things will get "sausaged", but I'll look into TokenStreamToAutomaton to see
if I can understand it enough to use it.

What might still happen is that a phrase "u s of america" would match, as is implied on the
second question on the comment above, which is a lesser problem but still kind of wrong. More
on that below.)

> SynonymFilter should generate a correct (or, at least, better) graph
> --------------------------------------------------------------------
>                 Key: LUCENE-6582
>                 URL:
>             Project: Lucene - Core
>          Issue Type: Bug
>            Reporter: Ian Ribas
>         Attachments: LUCENE-6582.patch, after.png, after2.png, before.png
> Some time ago, I had a problem with synonyms and phrase type queries (actually, it was
elasticsearch and I was using a match query with multiple terms and the "and" operator, as
better explained here:
> That issue led to some work on Lucene: LUCENE-6400 (where I helped a little with tests)
and  LUCENE-6401. This issue is also related to LUCENE-3843.
> Starting from the discussion on LUCENE-6400, I'm attempting to implement a solution.
Here is a patch with a first step - the implementation to fix "SynFilter to be able to 'make
positions'" (as was mentioned on the [issue|]).
In this way, the synonym filter generates a correct (or, at least, better) graph.
> As the synonym matching is greedy, I only had to worry about fixing the position length
of the rules of the current match, no future or past synonyms would "span" over this match
(please correct me if I'm wrong!). It did require more buffering, twice as much.
> The new behavior I added is not active by default, a new parameter has to be passed in
a new constructor for {{SynonymFilter}}. The changes I made do change the token stream generated
by the synonym filter, and I thought it would be better to let that be a voluntary decision
for now.
> I did some refactoring on the code, but mostly on what I had to change for may implementation,
so that the patch was not too hard to read. I created specific unit tests for the new implementation
({{TestMultiWordSynonymFilter}}) that should show how things will be with the new behavior.

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