Message-ID: <d784945a-88d4-413b-947e-1ed402982595@illuminatedcomputing.com>
Date: Tue, 27 Aug 2024 11:11:35 -0700
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Subject: Re: Strange behaviors with ranges
To: pgsql-general@lists.postgresql.org
References: <77691006-45f1-4ef9-bc1b-2eecd44f7d0d@thefreecat.org>
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From: Paul Jungwirth <pj@illuminatedcomputing.com>
In-Reply-To: <77691006-45f1-4ef9-bc1b-2eecd44f7d0d@thefreecat.org>
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On 8/27/24 10:29, Jean-Christophe Boggio wrote:
> I have 2 very confusing behaviors when using ranges.
> 
> It all started with this query:
> 
>      WITH rangespaliers AS (
>          SELECT numrange( qtep1+1   , qtep2,  '[]') AS rangep FROM paliers JOIN tmp_limitcontrats 
> USING(idcontrat)
> --        SELECT numrange( qtep1+1   , qtep2,  '[]') AS rangep FROM paliers WHERE idcontrat=1003
>      )
>      ,rangespaliers2 AS (
>          select *
>          FROM rangespaliers
>          WHERE rangep <> NUMRANGE(NULL, NULL) -- ERROR IS HERE
>      )
>      select * from rangespaliers2;
> 
> When I run this query, I get the error "Range lower bound must be less than or equal to range upper 
> bound".
> 
> (a) If I comment out the line marked "ERROR IS HERE", I don't have an error (but I'm missing the 
> filter of course).
> 
> (b) Also, if I uncomment line 3 and comment out line 2, I get the correct behavior. Very strange 
> thing is that tmp_limitcontrats has only one row which contains "idcontrat=1003".

The issue is the order-of-operations used by the planner. If I put EXPLAIN on your last query, I see:

  Hash Join  (cost=16.64..109.90 rows=2410 width=64)
    Hash Cond: (tmp_limitcontrats.idcontrat = paliers.idcontrat)
    ->  Seq Scan on tmp_limitcontrats  (cost=0.00..35.50 rows=2550 width=4)
    ->  Hash  (cost=14.27..14.27 rows=189 width=12)
          ->  Seq Scan on paliers  (cost=0.00..14.27 rows=189 width=12)
                Filter: (numrange(((qtep1 + 1))::numeric, (qtep2)::numeric) <> '(,)'::numrange)

So we are applying that filter to every row in paliers, not just the one with idcontrat = 1003.

Indeed this simplified version also fails:

SELECT numrange(qtep1+1,qtep2) as rangep FROM paliers;

Yours,

-- 
Paul              ~{:-)
pj@illuminatedcomputing.com