| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Peter Geoghegan <pg(at)heroku(dot)com> |
| Cc: | Alexander Korotkov <aekorotkov(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: jsonb contains behaviour weirdness |
| Date: | 2014-09-12 18:34:23 |
| Message-ID: | 19539.1410546863@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Peter Geoghegan <pg(at)heroku(dot)com> writes:
> On Fri, Sep 12, 2014 at 11:09 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> I'm confused. Are you proposing to return to sort + de-dup of JSON
>> arrays? Surely that is completely broken. Arrays are ordered.
> Sorry, my earlier remarks were premature. In fact, that alteration
> only applied to existence, not containment. However, arrays are
> ordered for the purposes of equality, but not containment.
My remarks were also premature, because looking back at the referenced
commit, I see what it removed was a sort and de-dup as a preliminary step
in containment comparisons, not as a generic alteration of array contents.
So that was sane enough, though I concur with Heikki's opinion that it
likely failed to be a performance win.
regards, tom lane
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