Re: Performance issue after creating partitions

You need to change your query to not use the trunc. The TRUNC statement forces it to trunc every row in the table.

If you do order_date >= to_date(..) and order_date < to_date(..) + interval '1' day, it will use the partition range to narrow down to the correct partition first.

Sent from my iPhone

> On Aug 24, 2022, at 6:41 PM, Teja Jakkidi <teja(dot)jakkidi05(at)gmail(dot)com> wrote:
>
> Hello Admin team,
>
> We have a Postgres 13 server set up on Google Cloud. Recently we created partitions as below for the tables:
> Range on ‘order_date’ column
> List on ‘country_code’ column
>
> Quarterly partitions for range.
>
> Order date column is a time stamp column and when we are using this column as a filter in where condition : trunc(order_date) = to_date(’2022-04-01’,’YYYY-MM-DD’), the query scans all the partitions dated back from the year 2000. So, instead of going to the 2022 Q2 partition directly, the query is scanning all the partitions.
> But when we remove the trunc() function and just specify order_date =‘2022-04-01 07:02:30’, this works as expected. It goes to the correct partition directly and gets the data.
> Can Anyone help me on what’s happening in the first case and why all the partitions are being scanned?
> For the first case, when there is a non partition table, it is behaving way better.
>
> Thanks,
> J. Teja.
>