Re: WIP: index support for regexp search - Mailing list pgsql-hackers

From Alexander Korotkov
Subject Re: WIP: index support for regexp search
Date
Msg-id CAPpHfdvVu9J-2sf4T0NMh_fGdiMqXvdMQBY9P=doFw=Q6c0CUA@mail.gmail.com
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In response to Re: WIP: index support for regexp search  (Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>)
Responses Re: WIP: index support for regexp search  (Alexander Korotkov <aekorotkov@gmail.com>)
Re: WIP: index support for regexp search  (Alexander Korotkov <aekorotkov@gmail.com>)
List pgsql-hackers
On Fri, Jan 20, 2012 at 12:30 AM, Heikki Linnakangas <heikki.linnakangas@enterprisedb.com> wrote:
The code badly needs comments. There is no explanation of how the trigram extraction code in trgm_regexp.c works.
Sure. I hoped to find a time for comments before commitfest starts. Unfortunately I didn't, sorry.
 
Guessing from the variable names, it seems to be some sort of a coloring algorithm that works on a graph, but that all needs to be explained. Can this algorithm be found somewhere in literature, perhaps? A link to a paper would be nice.
I hope it's truly novel. At least application to regular expressions. I'm going to write a paper about it.
 
Apart from that, the multibyte issue seems like the big one. Any way around that?
Conversion of pg_wchar to multibyte character is the only way I found to avoid serious hacking of existing regexp code. Do you think additional function in pg_wchar_tbl which converts pg_wchar back to multibyte character is possible solution?

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With best regards,
Alexander Korotkov.

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