Thank you for your feedback!
On Fri, Jan 20, 2012 at 3:33 AM, Erik Rijkers <er(at)xs4all(dot)nl> wrote:
> The patch yields spectacular speedups with small, simple-enough regexen.
> But it does not do a
> good enough job when guessing where to use the index and where fall back
> to Seq Scan. This can
> lead to (also spectacular) slow-downs, compared to Seq Scan.
Could you give some examples of regexes where index scan becomes slower
than seq scan?
> I guessed that MAX_COLOR_CHARS limits the character class size (to 4, in
> your patch), is that
> true? I can understand you want that value to be low to limit the above
> risk, but now it reduces
> the usability of the feature a bit: one has to split up larger
> char-classes into several smaller
> ones to make a statement use the index: i.e.:
Yes, MAX_COLOR_CHARS is number of maximum character in automata color when
that color is divided to a separated characters. And it's likely there
could be better solution than just have this hard limit.
> Btw, it seems impossible to Ctrl-C out of a search once it is submitted; I
> suppose this is
> normally necessary for perfomance reasons, but it would be useful te be
> able to compile a test
> version that allows it. I don't know how hard that would be.
I seems that Ctrl-C was impossible because procedure of trigrams
exctraction becomes so long while it is not breakable. It's not difficult
to make this procedure breakable, but actually it just shouldn't take so
> There is also a minor bug, I think, when running with 'set
> enable_seqscan=off' in combination
> with a too-large regex:
Thanks for pointing. Will be fixed.
With best regards,
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