I have attached a patch for phrase search with respect to the cvs head.
Basically it takes a a phrase (text) and a TSVector. It checks if the
relative positions of lexeme in the phrase are same as in their
positions in TSVector.
Ideally, phrase search should be implemented as new operator in tsquery, say #
with optional distance. So, tsquery 'foo #2 bar' means: find all texts where
'bar' is place no far than two word from 'foo'. The complexity is about complex
boolean expressions ( 'foo #1 ( bar1 & bar2 )' ) and about several languages as
norwegian or german. German language has combining words, like a footboolbar -
and they have several variants of splitting, so result of to_tsquery('foo #
footboolbar') will be a 'foo # ( ( football & bar ) | ( foot & ball & bar ) )'
where variants are connected with OR operation.
Of course, phrase search should be able to use indexes.
If the configuration for text search is "simple", then this will produce
exact phrase search. Otherwise the stopwords in a phrase will be ignored
and the words in a phrase will only be matched with the stemmed lexeme.
Your solution can't be used as is, because user should use tsquery too to use an
index:
column @@ to_tsquery('phrase search') AND is_phrase_present('phrase search',
column)
First clause will be used for index scan and it will fast search a candidates.
For my application I am using this as a separate shared object. I do not
know how to expose this function from the core. Can someone explain how
to do this?
Look at contrib/ directory in pgsql's source code - make a contrib module from
your patch. As an example, look at adminpack module - it's rather simple.
Comments of your code:
1)
+#ifdef PG_MODULE_MAGIC
+PG_MODULE_MAGIC;
+#endif
That isn't needed for compiled-in in core files, it's only needed for modules.
2)
use only /**/ comments, do not use a // (C++ style) comments
--
Teodor Sigaev E-mail: [EMAIL PROTECTED]
WWW: http://www.sigaev.ru/
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