On 07/24/2017 01:40 AM, PT wrote:
> In this example you count approximately 40,000,000 values, which is
> about 40% of the table.
4 000 000 (:
> If you really need these queries to be faster, I would suggest
> materializing the data, i.e. create a table like:
>
> CREATE TABLE id_counts (
> id BIGINT PRIMARY KEY,
> num BIGINT
> )
>
> Then use a trigger or similar technique to keep id_counts in sync
> with the id table. You can then run queries of the form:
>
> SELECT sum(num) FROM id_counts WHERE id IN :values:
>
> which I would wager houseboats will be significantly faster.
I use count only for example because it uses seqscan. I want optimize
IN-clause ;-).
Thanks.
