Re: [HACKERS] [BUGS] Concurrent ALTER SEQUENCE RESTART Regression

Hi,


On 2017-05-11 16:27:48 -0400, Peter Eisentraut wrote:
> On 5/10/17 12:24, Andres Freund wrote:
> > Upthread I theorized whether
> > that's actually still meaningful given fastpath locking and such, but I
> > guess we'll have to evaluate that.
> 
> I did some testing.

That's with the open_share_lock stuff ripped out entirely, replaced by a
plain lock acquisition within the current subxact?


> (These were within each other's variance over several runs.)
> 
> 9.2 unpatched
> Time: 64868.305 ms
> 
> 9.2 patched
> Time: 60585.317 ms
> 
> (So without contention fast-path locking beats the extra dance that
> open_share_lock() does.)

That's kind of surprising, I really wouldn't have thought it'd be faster
without.  I guess it's the overhead of sigsetjmp().  Cool.


- Andres