Суббота, 7 января 2023, 20:23 +03:00 от Peter J. Holzer <hjp-pgsql@xxxxxx>:
On 2023-01-07 07:40:01 -0600, Ron wrote:
> On 1/7/23 05:29, Peter J. Holzer wrote:
> If I understood correctly, you have to delete about 3 million records
> (worst case) from the main table each day. Including the other 8 tables
> those are 27 million DELETE queries each of which deletes only a few
> records. That's about 300 queries per second. I'd be worried about
> impacting performance on other queries at this rate.
>
>
> 300 records/second. Fewer DELETE statements if there are one-many
> relationships with the child tables.
Nope:
| Each of these tables' daily record increment is on an average 2 to 3
| million
I am assuming that the main table is typical, so there will be 2 to 3
million DELETEs from the main table and also from each of the other 8
tables (which may delete 0, 1, or more records). Also, it was mentioned
that only some of these tables have a direct FK relationship, so the
DELETE queries against the other tables may be (much) more expensive
than a simple `delete from my_table where main_id = :1`.
hp
--
_ | Peter J. Holzer | Story must make more sense than reality.
|_|_) | |
| | | hjp@xxxxxx | -- Charles Stross, "Creative writing
__/ | http://www.hjp.at/ | challenge!"
So one may consider deleting from child tables, and only after that delete from main table, avoiding enforcing foreign key during delete. Also consider deletes by relatively small chunks, in loop.
