Re: [HACKERS] MERGE SQL Statement for PG11

On 30 January 2018 at 21:47, Peter Geoghegan <pg(at)bowt(dot)ie> wrote:

> I'm glad that we all seem to agree that serialization failures as a
> way of dealing with concurrency issues in READ COMMITTED mode are a
> bad idea.

ERRORs are undesirable, yet safe and correct. Doing better is as yet
unclear if it can be done correctly in all cases, or whether a
practical subset exists.

> Unfortunately, I still think that we have a lot of work
> ahead of us when it comes to agreeing to the right semantics with READ
> COMMITTED conflict handling with multiple WHEN ... AND quals.

OK

> I see that your v14 still has the serialization error, even though
> it's now clear that nobody wants to go that way. So...where do we go
> from here? (For the avoidance of doubt, this is *not* a rhetorical
> question.)

This way forward is new. We're trying it, but it may not be possible.
I haven't made it work yet.

If we can find a way to do this, we will. If you want to propose some
code, please do.

I think it would be very helpful if we could discuss everything with
direct relevance to v14, so this becomes a patch review, not just a
debate.
i.e. which isolation test would we like to change from ERROR to
success? or which new test would you like to add?

Thanks

--
Simon Riggs http://www.2ndQuadrant.com/
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