On Mon, Dec 28, 2020 at 7:51 AM Christopher Baines <m...@cbaines.net> 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. https://www.postgresql.org/docs/current/sql-altertable.html I am not sure if it will resolve your query problems though.
