jaroet <jaroet@xxxxxxxxx> writes: > Internally we upgraded from 9.2 to 9.5 en we had defined an median function. > This became about 7 to 8 times slower using the same functions. > ... > We found that the median function that fills an array is the slow part. When > we change our SQL from median(fieldname) to > _final_median(array_agg(fieldname)) the performance is even 3 times faster > than on 9.2. > So it looks like the array_agg function when used in a self-defined function > is extremly slow. But you're not using array_agg, you're using array_append. That isn't what array_agg is built on. Unfortunately, what array_agg is built on is something that isn't very convenient to use for custom aggregates, because it relies on an "internal"-type transition value. I don't have any magic fix for getting this back to the previous level of performance, but have started a thread about it on -hackers: https://www.postgresql.org/message-id/6315.1477677885%40sss.pgh.pa.us regards, tom lane -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
