From: | Denis Papathanasiou <denis(dot)papathanasiou(at)gmail(dot)com> |
---|---|
To: | pgsql-general(at)postgresql(dot)org |
Subject: | Optimal indexing of Full Text Search (ts_vector & ts_query) columns? |
Date: | 2010-08-21 16:26:35 |
Message-ID: | 4C6FFE3B.5010601@gmail.com |
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Lists: | pgsql-general |
After reading the documentation on Full Text Search here
http://www.postgresql.org/docs/8.4/interactive/textsearch-tables.html I
created the following table and index:
CREATE TABLE item (
pk uuid primary key,
...
[more columns here]
...
searchable_text text not null
);
CREATE INDEX item_eng_searchable_text_idx ON item USING
gin(to_tsvector('english', searchable_text));
Note that unlike the example, I did not want to define the searchable
text column in the table as being being of type ts_vector(), because the
text is not exclusively English.
My question is: when I query the table like this, am I getting the full
benefit of the index?
select pk from item where searchable_text @@ plainto_tsquery('search
phrase');
Also, since there will be cases where the contents of searchable_text
will be known exactly, i.e., the query will be:
select pk from item where searchable_text = 'exact phrase';
is there any harm in adding a second, regular index on searchable_text
like this, or does the gin/ts_vector() index cover me in both types of
queries?
CREATE INDEX item_searchable_text_idx ON item (searchable_text);
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