The following bug has been logged on the website:
Bug reference: 14675
Logged by: Martin Walpen
Email address: walpino@gmx.ch
PostgreSQL version: 9.6.3
Operating system: CentOS Linux release 7.3.1611
Description:
Hello
we wanna upgrade our Installations from Version 9.5.3 to 9.6.3
everything works fine with the pg_upgrade
after the Upgrade process we encountered an performance issue
we have a join in a select statement
simply said, it looks like
select....
from
where column_a = coalesce(col_b, coalesce(col_c, col_b))
this was fast on 9.5.3
but now on 9.6.3 is is slow really really slow
the explain plan looks similar and not big difference
when I changed this query to
select....
from
where column_a = coalesce(col_b, col_c, col_b)
which should be the same
it was as fast as on 9.5.3
do you have any explanation for that?
thanks
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