| From: | Alexander Korotkov <aekorotkov(at)gmail(dot)com> |
|---|---|
| To: | Erik Rijkers <er(at)xs4all(dot)nl> |
| Cc: | Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Tomas Vondra <tv(at)fuzzy(dot)cz>, pgsql-hackers(at)postgresql(dot)org, pavel(dot)stehule(at)gmail(dot)com |
| Subject: | Re: WIP: index support for regexp search |
| Date: | 2012-12-18 08:45:27 |
| Message-ID: | CAPpHfdsLXeLT5bt+mLf3gDwmjojSk9U0fepLr8dPrsLPKOwuzA@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, Dec 18, 2012 at 11:45 AM, Erik Rijkers <er(at)xs4all(dot)nl> wrote:
> On Tue, December 18, 2012 08:04, Alexander Korotkov wrote:
> I ran the same test again: HEAD versus trgm_regex v6, 7 and 9. In v9
> there is some gain but also
> some regression.
>
> It remains a difficult problem...
>
> If I get some time in the holidays I'll try to diversify the test program;
> it is now too simple.
>
Note, that regexes which contains {,n} are likely not what do you expect.
test=# select 'xq' ~ 'x[aeiou]{,2}q';
?column?
----------
f
(1 row)
test=# select 'xa{,2}q' ~ 'x[aeiou]{,2}q';
?column?
----------
t
(1 row)
You should use {0,n} to express from 0 to n occurences.
------
With best regards,
Alexander Korotkov.
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