On 4/6/20 9:17 PM, David Steele wrote:
Hi Grigory,
Hello!
On 4/5/20 8:02 PM, Grigory Smolkin wrote:
Hello, hackers!
I`m investigating a complains from our clients about archive recovery
speed been very slow, and I`ve noticed a really strange and, I think,
a very dangerous recovery behavior.
When running multi-timeline archive recovery, for every requested
segno startup process iterates through every timeline in restore
target timeline history, starting from highest timeline and ending in
current, and tries to fetch the segno in question from this timeline.
<snip>
Is there a reason behind this behavior?
Also I`ve attached a patch, which fixed this issue for me, but I`m
not sure, that chosen approach is sound and didn`t break something.
This sure looks like [1] which has a completed patch nearly ready to
commit. Can you confirm and see if the proposed patch looks good?
Well I`ve been testing it all day and so far nothing is broken.
But this foreach(xlog.c:3777) loop looks very strange to me, it is not
robust, we are blindly going over timelines and feeding recovery some
files, hoping they are the right ones. I think we can do better, because:
1. we know whether or not we are running multi-timeline recovery
2. we know next timeline ID and can calculate switchpoint segment
3. make an informed decision about from what timeline we must requesting
files now.
I will work on it.
--
Grigory Smolkin
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company
