PGA usage after 19c upgrade

Hi,

A month ago we updated a Database from 12 to 19.12. After this we noticed poor performance.

First of all we can see high use of PGA.

We have this parameters:

pga_aggregate_limit big integer 0

pga_aggregate_target big integer 1536M

sga_max_size big integer 10G

sga_target big integer 6G

After upgrade, even there are no/low activity, use of PGA is always growning (now at 3,5 G)

Is this a normal behavior?

Why the instance take so much memory?

Data from OEM before and after the upgrade:

Jan 23, 2022 11:00:00 PM

1,634.24

Jan 24, 2022 11:00:00 PM

1,598.59

Jan 25, 2022 11:00:00 PM

1,585.88

Jan 26, 2022 11:00:00 PM

1,585.21

Jan 27, 2022 11:00:00 PM

1,576.04

Jan 30, 2022 11:00:00 PM