Re: Adding skip scan (including MDAM style range skip scan) to nbtree

On 9/12/24 16:49, Matthias van de Meent wrote:
> On Mon, 9 Sept 2024 at 21:55, Peter Geoghegan <pg@bowt.ie> wrote:
>>
> ...
> 
> The fix in 0001 is relatively simple: we stop backends from waiting
> for a concurrent backend to resolve the NEED_PRIMSCAN condition, and
> instead move our local state machine so that we'll hit _bt_first
> ourselves, so that we may be able to start the next primitive scan.
> Also attached is 0002, which adds tracking of responsible backends to
> parallel btree scans, thus allowing us to assert we're never waiting
> for our own process to move the state forward. I found this patch
> helpful while working on solving this issue, even if it wouldn't have
> found the bug as reported.
> 

No opinion on the analysis / coding, but per my testing the fix indeed
addresses the issue. The script reliably got stuck within a minute, now
it's running for ~1h just fine. It also checks results and that seems
fine too, so that seems fine too.


regards

-- 
Tomas Vondra