On Wed, 2023-06-28 at 17:29 +0200, Marc Millas wrote: > https://explain.depesz.com/s/Opk0 > > The big table (10 billions raws) is split in around 130 partitions, one by month. > the ladate column is the partition key, and it does have 1 value for each partition. > there is an index on the numfic column. the distribution of values for that column may differ before and after 2019 january. > > The request is executed in a loop for all ten years of data, year 1,2,3, then year2,3,4 etc > that request is also executed for columns other than cod, one column at a time (there are 107 columns...) > > I dont understand why the planner use a filter on the date, as its already within the partition structure.
If the grouping column is the partitioning key, try to set enable_partitionwise_join = on.
Otherwise, your best bet is to create an index that covers both WHERE conditions, or a covering index, which will get you the best result:
CREATE INDEX ON table1 (numfic, ladate) INCLUDE (cod, nb_obs);
Hi Laurenz, as said, in each partition there is only one value for ladate.
I don't understand the point of creating an index for the tens of millions rows of each partition, index wich will contain the very same unique value within all of the index.
I did set enable_partitionwise_join = 'on' and retry,