Re: Prefix operator for text and spgist support

From: Ildus Kurbangaliev <i(dot)kurbangaliev(at)postgrespro(dot)ru>
To: Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru>
Cc: Teodor Sigaev <teodor(at)sigaev(dot)ru>, Arthur Zakirov <a(dot)zakirov(at)postgrespro(dot)ru>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: Prefix operator for text and spgist support
Date: 2018-03-29 11:36:34
Message-ID: 20180329143634.33c53348@wp.localdomain
Views: Raw Message | Whole Thread | Download mbox | Resend email
Lists: pgsql-hackers

On Fri, 23 Mar 2018 11:45:33 +0300
Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru> wrote:

> On Thu, Mar 22, 2018 at 7:09 PM, Teodor Sigaev <teodor(at)sigaev(dot)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

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.

Ildus Kurbangaliev
Postgres Professional:
Russian Postgres Company

Attachment Content-Type Size
prefix_operator_and_spgist_v5.patch text/x-patch 17.0 KB

In response to


Browse pgsql-hackers by date

  From Date Subject
Next Message Andrew Gierth 2018-03-29 11:37:05 Re: committing inside cursor loop
Previous Message Alexander Korotkov 2018-03-29 11:32:05 Fix src/test/subscription/t/ header comment