Re: tsearch matching "barrier"

Hi Florian,

"FA" == Florian Aumeier writes:

 FA> Hi yes, have a look at the "Index structured documents" section in
 FA> http://www.sai.msu.su/~megera/wiki/Tsearch_V2_Notes

thanks for reply, but i did not understand how to apply this to my
problem. the "structured documents" seem to support up to 4 different
sections, but i need unlimited number, and being able to find documents
where at least one of the sections matches the query independently of
other sections.

to clarify my needs, i put the following example below.

create temp table tmp_fts (pk_doc integer, ix tsvector[]);
insert into tmp_fts (pk_doc, ix) values (1, ARRAY[to_tsvector('aaa aab'),to_tsvector('aac aad aaf'),to_tsvector('test')]);
insert into tmp_fts (pk_doc, ix) values (2, ARRAY[to_tsvector('aab aac aaf'),to_tsvector('test aad aag aaf')]);

this creates 2 records, 1 per "document", and the ix field contains an
array of tsvector values, which are thought to be logically independent
parts of the document.

document #1 contains 3 parts shown on separate lines below:

  aaa aab
  aac aad aaf
  test

document #2 contains 2 parts shown on separate lines below:

  aab aac aaf
  test aad aag aaf

the search should find the document only if one of document's parts
wholly matches the query.

the following works:

select pk_doc from tmp_fts where to_tsquery('aab & aaf') @@ any (ix); -- returns 2
select pk_doc from tmp_fts where to_tsquery('aac & aad') @@ any (ix); -- returns 1
select pk_doc from tmp_fts where to_tsquery('aad & aaf') @@ any (ix); -- returns 1 & 2

e.g. a search for 'aab & aaf' returns only document #2, but not
document #1, although document #1 contains the words 'aab' and 'aaf',
but only in separate parts, - no part contains them together.

but unfortunately, indexing does not work:

-- create index ind_tmp_fts on tmp_fts using gin (ix); -- this does not work

i was wondering whether tsearch perhaps could be enhanced to understand
some "barrier token" which will divide the document into parts.

then, i could solve this without creating arrays, by indexing document #1 as:

  aaa aab <BARRIER> aac aad aaf <BARRIER> test

and indexing document #2 as:

  aab aac aaf <BARRIER> test aad aag aaf

and having the @@ operator only search inside parts separated by a
barrier, but not between them. e.g. @@ should not find 'aab & aaf'
in document #1, because they are separated by a barrier token.

Best,
v.


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