Re: order by

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От Adam Scott
Тема Re: order by
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Msg-id CA+s62-MiEFrGTjg+Bmhrk-U5EYaNkgFKDf4Sv6oVpX2TS_EPJw@mail.gmail.com
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Ответ на order by  (Marc Millas <marc.millas@mokadb.com>)
Ответы Re: order by
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Check the index creation has NULLS FIRST (or LAST) on both indexes that are used. Use explain to see what indexes are used 


On Thu, May 11, 2023, 7:30 AM Marc Millas <marc.millas@mokadb.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

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