Re: Very newbie question

On 10/23/23 10:13, Олег Самойлов wrote:
> Back pardon, but I have a very newbie question. I have a partitioned table, partitioned by primary bigint key, size of partition 10000000. I need to get the number of partition which need to archive, which has all rows are olden then 3 month. Here is query:
>
> SELECT id/10000000 as partition
> FROM delivery
> GROUP BY partition
> HAVING max(created_at) < CURRENT_DATE - '3 month'::interval;
>
> The 'id/10000000 as partition' is a number of the partition, it later will be used inside the partition name.
> The query runs long by sequence scan. Has anyone any ideas how to rewrite query so it will use any index?

Maybe:

SELECT DISTINCT id/10000000 as partition
FROM delivery
WHERE max(created_at) < CURRENT_DATE - '3 month'::interval;

I haven't tried it, though.

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