postgres query performance I can't find a good way to rewrite this query or improve the performance:
query:
update company_holding c
set issuer_stim_buy_quarter = sq.estim_quarter_buy
from (select h.company_id
            ,h.issuer_cusip
            ,var_quarter as quarter
            ,min(h.quarter) as estim_quarter_buy
      from company_holding h
      where h.quarter &lt;= var_quarter
        and h.issuer_tot_share &gt; 0
      group by h.company_id, quarter, h.issuer_cusip
     ) sq
where c.company_id = sq.company_id
  and c.issuer_cusip = sq.issuer_cusip
  and c.quarter = sq.quarter

company_holding is a partitioned table.
This is the explain analyze: https://explain.depesz.com/s/5rjU
Most of the time is spent aggregating and sorting the data.
I don't know how the tables are partitioned, but if the partitioning key is part of the join condition or the aggregate can be calculated partition by partition, you might benefit by setting enable_partitionwise_aggregate and enable_partitionwise_join to on.
There is not much more I can say with that little information.