I suggest you work on more general approach, see
http://www.sai.msu.su/~megera/wiki/2009-08-12 for example.
btw, I don't like you changed ts_rank_cd arguments.
Oleg
On Fri, 27 Jan 2012, karave...@mail.bg wrote:
Hello,
I have developed a variation of cover density ranking functions that counts
only covers that are lesser than a specified limit. It is useful for finding
combinations of terms that appear nearby one another. Here is an example of
usage:
-- normal cover density ranking : not changed
luben=> select ts_rank_cd(to_tsvector('a b c d e g h i j k'),
to_tsquery('a&d'));
ts_rank_cd
------------
0.0333333
(1 row)
-- limited to 2
luben=> select ts_rank_cd(2, to_tsvector('a b c d e g h i j k'),
to_tsquery('a&d'));
ts_rank_cd
------------
0
(1 row)
luben=> select ts_rank_cd(2, to_tsvector('a b c d e g h i j k a d'),
to_tsquery('a&d'));
ts_rank_cd
------------
0.1
(1 row)
-- limited to 3
luben=> select ts_rank_cd(3, to_tsvector('a b c d e g h i j k'),
to_tsquery('a&d'));
ts_rank_cd
------------
0.0333333
(1 row)
luben=> select ts_rank_cd(3, to_tsvector('a b c d e g h i j k a d'),
to_tsquery('a&d'));
ts_rank_cd
------------
0.133333
(1 row)
Find attached a path agains 9.1.2 sources. I preferred to make a patch, not a
separate extension because it is only 1 statement change in calc_rank_cd
function. If I have to make an extension a lot of code would be duplicated
between backend/utils/adt/tsrank.c and the extension.
I have some questions:
1. Is it interesting to develop it further (documentation, cleanup, etc) for
inclusion in one of the next versions? If this is the case, there are some
further questions:
- should I overload ts_rank_cd (as in examples above and the patch) or should I
define new set of functions, for example ts_rank_lcd ?
- should I define define this new sql level functions in core or should I go
only with this 2 lines change in calc_rank_cd() and define the new functions as
an extension? If we prefer the later, could I overload core functions with
functions defined in extensions?
- and finally there is always the possibility to duplicate the code and make an
independent extension.
2. If I run the patched version on cluster that was initialized with unpatched
server, is there a way to register the new functions in the system catalog
without reinitializing the cluster?
Best regards
luben
--
Luben Karavelov
Regards,
Oleg
_____________________________________________________________
Oleg Bartunov, Research Scientist, Head of AstroNet (www.astronet.ru),
Sternberg Astronomical Institute, Moscow University, Russia
Internet: o...@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(495)939-16-83, +007(495)939-23-83
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