On Mon, Dec 28, 2020 at 7:51 AM Christopher Baines <mail@xxxxxxxxxxx> wrote:
derivation_inputs:
COUNT(*): 285422539
reltuples: 285422528
derivation_id:
COUNT(DISTINCT): 7508610
n_distinct: 4336644 (~57% of the true value)
derivation_output_id:
COUNT(DISTINCT): 5539406
n_distinct: 473762 (~8% of the true value)
If you expect the ratio of distinct of derivation_output_id values to be roughly linear going forward, you can set a custom value for n_distinct on the column (currently seems like -.0194, aka distinct count of derivation_output_id divided by reltuples of the table). You could also do this analysis every month or six and set the custom value as needed.
I am not sure if it will resolve your query problems though.
