Fujii Masao
masao****@gmail*****
2013年 10月 4日 (金) 12:45:29 JST
On Fri, Oct 4, 2013 at 12:23 PM, Amit Langote <amitl****@gmail*****> wrote: > On Fri, Oct 4, 2013 at 11:25 AM, Fujii Masao <masao****@gmail*****> wrote: >> On Fri, Oct 4, 2013 at 9:26 AM, Amit Langote <amitl****@gmail*****> wrote: >>> On Fri, Oct 4, 2013 at 3:44 AM, Fujii Masao <masao****@gmail*****> wrote: >>>> On Sat, Sep 28, 2013 at 6:16 PM, Beena Emerson <memis****@gmail*****> wrote: >>>>> Please find attached the updated patch to rebase against the new HEAD and >>>>> also implements the comments I had given before. >>>> >>>> +PG_FUNCTION_INFO_V1(set_bigm_limit); >>>> +Datum set_bigm_limit(PG_FUNCTION_ARGS); >>>> + >>>> +PG_FUNCTION_INFO_V1(show_bigm_limit); >>>> +Datum show_bigm_limit(PG_FUNCTION_ARGS); >>>> >>>> I think that it's better to treat the similarity limit as a custom GUC variable >>>> rather than implementing special functions like the above. If we do that, >>>> we can change and show the value of the similarity limit as follows. Thought? >>>> >>>> SET pg_bigm.similarity_limit TO 0.001; >>>> SHOW pg_bigm.similarity_limit; >>>> >>> >>> I think it looks better. >>> >>>> +/* GIN does not support ordering operators, wait for GiST support... >>>> + >>>> +CREATE FUNCTION bigm_similarity_dist(text,text) >>>> +RETURNS float4 >>>> +AS 'MODULE_PATHNAME' >>>> +LANGUAGE C STRICT IMMUTABLE; >>>> >>>> So we should not include bigm_similarity_dist() at all? >>>> >>> >>> It could be added I think. I guess I forgot to remove the comment >>> around the function itself. So, >> >> Is it really worth adding that even if pg_bigm supports only GIN index? >> > > On second thought, I also think just adding bigm_similarity_dist() > function would not serve any purpose as such. Since, GIN does not > support ordering operators, we can not add it in any useful way for > now. Looking at pg_trgm's distance operator > > ALTER OPERATOR FAMILY gist_trgm_ops USING gist ADD > OPERATOR 2 <-> (text, text) FOR ORDER BY > pg_catalog.float_ops, > > Above can not be done with "USING gin". It gives following; > > ERROR: access method "gin" does not support ordering operators > > >> The pg_trgm document says >> >> ---------- >> SELECT t, t <-> 'word' AS dist >> FROM test_trgm >> ORDER BY dist LIMIT 10; >> >> This can be implemented quite efficiently by GiST indexes, but not >> by GIN indexes. >> ---------- >> >> Is this related to the comment that you added into the patch? >> > > Yes. But, after these considerations, we should not let > bigm_similarity_dist() in just yet. > > Thoughts? Agreed. I committed the add-similarity-op-v6.patch. Need to add the regression test and update the document later. Regards, -- Fujii Masao
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