Thread: Dynamic creation of list partitions in highly concurrent write environment
Hello everyone.
We are attempting to evaluate list partitioning over hash partitioning (which we currently use) to better facilitate dropping tables that distinctly model devices we wish to purge. We don't want to use a DML statement for cleanup since these tables can contain billions of rows otherwise. Using PG15, we've hit a snag;
We're attempting to use declarative partitioning syntax in a function run as an after trigger; we hit deadlocks. We try the older inheritance alternative, we still hit deadlocks. I appreciate this is generally because creating tables isn't a concurrently supported operation. Here's the general approach we have, without code and with hypothetical model, since I'm writing this hastily;
table devices; <-- After trigger on here
table routes; <-- To create physical partition for this logical table
table route_for_device_N; <-- The dynamically created partition
--
We don't know the device names and thus partitions up front, hence the need for dynamic creation. How do you go about doing this or is it folly!?
Cheers
Jim
Jim Vanns
Principal Production Engineer
Industrial Light & Magic, London
Principal Production Engineer
Industrial Light & Magic, London
Jim Vanns <jvanns@ilm.com> writes:
> Here's the general approach we have, without code and with hypothetical
> model, since I'm writing this hastily;
> table devices; <-- After trigger on here
> table routes; <-- To create physical partition for this logical table
> table route_for_device_N; <-- The dynamically created partition
> We don't know the device names and thus partitions up front, hence the need
> for dynamic creation. How do you go about doing this or is it folly!?
Sounds like folly, TBH. You're going to end with a ridiculous number
of partitions of the routes table, which will not be good for performance.
regards, tom lane
Yeah, that's a known concern - hence the evaluation as part of the list vs. hash comparison ;)
Jim
On Thu, 1 Jun 2023 at 14:32, Tom Lane <tgl@sss.pgh.pa.us> wrote:
Jim Vanns <jvanns@ilm.com> writes:
> Here's the general approach we have, without code and with hypothetical
> model, since I'm writing this hastily;
> table devices; <-- After trigger on here
> table routes; <-- To create physical partition for this logical table
> table route_for_device_N; <-- The dynamically created partition
> We don't know the device names and thus partitions up front, hence the need
> for dynamic creation. How do you go about doing this or is it folly!?
Sounds like folly, TBH. You're going to end with a ridiculous number
of partitions of the routes table, which will not be good for performance.
regards, tom lane
Jim Vanns
Principal Production Engineer
Industrial Light & Magic, London
Principal Production Engineer
Industrial Light & Magic, London