RE: Speed up transaction completion faster after many relations are accessed in a transaction

From: David Rowley [mailto:david(dot)rowley(at)2ndquadrant(dot)com]
> It would be good to get your view on the
> shrink_bloated_locallocktable_v3.patch I worked on last night. I was
> unable to measure any overhead to solving the problem that way.

Thanks, it looks super simple and good. I understood the idea behind your patch is:

* Transactions that touch many partitions and/or tables are a special event and not normal, and the hash table bloat is an unlucky accident. So it's reasonable to revert the bloated hash table back to the original size.

* Repeated transactions that acquire many locks have to enlarge the hash table every time. However, the overhead of hash table expansion should be hidden behind other various processing (acquiring/releasing locks, reading/writing the relations, accessing the catalogs of those relations)

TBH, I think the linked list approach feels more intuitive because the resulting code looks what it wants to do (efficiently iterate over acquired locks) and is based on the classic book. But your approach seems to relieve people. So I'm OK with your patch.

I'm registering you as another author and me as a reviewer, and marking this ready for committer.

Regards
Takayuki Tsunakawa