Re: order by

From: Marc Millas <marc(dot)millas(at)mokadb(dot)com>
To: Adam Scott <adam(dot)c(dot)scott(at)gmail(dot)com>
Cc: pgsql-general(at)lists(dot)postgresql(dot)org
Subject: Re: order by
Date: 2023-05-11 14:55:47
Message-ID: CADX_1aaFYg7mQT8-ToWykfgzwmvQ8ziwytFrCr6Gv06aEsYgvg@mail.gmail.com
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Thanks,

I do know about index options.

that table have NO (zero) indexes.

Marc MILLAS
Senior Architect
+33607850334
www.mokadb.com

On Thu, May 11, 2023 at 4:48 PM Adam Scott <adam(dot)c(dot)scott(at)gmail(dot)com> wrote:

> Check the index creation has NULLS FIRST (or LAST) on both indexes that
> are used. Use explain to see what indexes are used
>
> See docs for create index:
> https://www.postgresql.org/docs/current/sql-createindex.html
>
> On Thu, May 11, 2023, 7:30 AM Marc Millas <marc(dot)millas(at)mokadb(dot)com> wrote:
>
>> Hi,
>>
>> I keep on investigating on the "death postgres" subject
>> but open a new thread as I don't know if it's related to my pb.
>>
>> I have 2 different clusters, on 2 different machines, one is prod, the
>> second test.
>> Same data volumes.
>>
>> On prod if I do
>> select col_a, count(col_a) from table_a group by col_a order by col_a
>> desc,
>> I get the numbers of NULL on top.
>> To get the number of NULL on top on the test db, I have to
>> select col_a, count(col_a) from table_a group by col_a order by col_a asc.
>>
>> so, it looks like there is something different within the b-tree operator
>> class of varchar (?!?)
>> between those 2 clusters.
>>
>> What can I check to to explain this difference as, to my understanding,
>> it's not a postgresql.conf parameter.
>>
>> thanks
>>
>> Marc MILLAS
>> Senior Architect
>> +33607850334
>> www.mokadb.com
>>
>>

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