From: | Paul Jungwirth <pj(at)illuminatedcomputing(dot)com> |
---|---|
To: | pgsql-general(at)lists(dot)postgresql(dot)org |
Subject: | Re: Strange behaviors with ranges |
Date: | 2024-08-27 18:11:35 |
Message-ID: | d784945a-88d4-413b-947e-1ed402982595@illuminatedcomputing.com |
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Lists: | pgsql-general |
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(at)illuminatedcomputing(dot)com
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