The main reason seems to be that RelationBuildPartitionDesc() will be called that many times within the same transaction, which perhaps we cannot do much about right away. But one thing we could do is to reduce the impact of memory allocations it does. They are currently leaked into the caller's context, which may not be reset immediately (such as PortalHeapMemory). Instead of doing it in the caller's context, use a temporary context that is deleted before returning. Attached is a patch for that. On my local development VM, `drop table table_with_2000_partitions` finished in 27 seconds with the patch instead of more than 20 minutes that it currently takes.
Thoughts?
Adding this to the open items list.
Thanks, Amit
PS: this was actually mentioned by Ragnar Ouchterlony who reported some bugs back in declarative partitioning in January [1]
