Re: Prefix operator for text and spgist support

On Fri, 23 Mar 2018 11:45:33 +0300
Alexander Korotkov <a.korotkov@postgrespro.ru> wrote:

> On Thu, Mar 22, 2018 at 7:09 PM, Teodor Sigaev <teodor@sigaev.ru>
> wrote:
> 
> > Patch looks resonable, but I see some place to improvement:
> > spg_text_leaf_consistent() only needs to check with
> > text_startswith() if reconstucted value came to leaf consistent is
> > shorter than given prefix. For example, if level >= length of
> > prefix then we guarantee that fully reconstracted is matched too.
> > But do not miss that you may need to return value for index only
> > scan, consult returnData field
> >
> > In attachment rebased and minorly edited version of your patch.  
> 
> 
> I took a look at this patch.  In addition to Teodor's comments I can
> note following.
> 
> * This line looks strange for me.
> 
> -            if (strategy > 10)
> +            if (strategy > 10 && strategy !=
> RTPrefixStrategyNumber)
> 
> It's not because we added strategy != RTPrefixStrategyNumber condition
> there.
> It's because we already used magic number here and now have a mix of
> magic number and macro constant in one line.  Once we anyway touch
> this place, could we get rid of magic numbers here?
> 
> * I'm a little concern about operator name.  We're going to choose @^
> operator for
> prefix search without any preliminary discussion.  However,
> personally I don't
> have better ideas :)

Teodor, Alexander, thanks for review. In new version I have added the
optimization in spgist using level variable and also got rid of magic
numbers.

About the operator it's actually ^@ (not @^ :)), I thought about it and
don't really have any idea what operator can be used instead.

Attached version 5 of the patch.

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Ildus Kurbangaliev
Postgres Professional: http://www.postgrespro.com
Russian Postgres Company