Thanks Florents,
I tried psql -c "select count(*)" . It has brought down the time from 30 minutes to 2 minutes.
Thanks alot.
Thanks Holger,
I'm going to try this query now.
Thanks,
Raj Kumar
On Mon, Jul 11, 2022 at 12:53 PM Florents Tselai <florents.tselai@xxxxxxxxx> wrote:
> On 11 Jul 2022, at 10:16 AM, Raj kumar <rajkumar820999@xxxxxxxxx> wrote:
>
> Hi,
>
> How can I improve "select count(*)" for larger tables? I'm doing a db migration and need to validate the data count.
> "select count(*) " queries are taking more than 30 minutes for some tables which is more than the downtime we have.
> Will work_mem increase help? or how can i speed up this row count?
Personally, whenever I’ve had slow count(*) or count (distinct id), eventually
I’ve resorted to Unix tools.
psql “select id from my_table" | sort -u | wc -l
The convenience/performance tradeoff depends heavily on your schema.
After all unix streams don’t know much about your integrity requirements.
>
> Thanks,
> Raj
