Re: [PATCH] SQL assertions prototype

On 2013-12-18 13:07:51 +0200, Heikki Linnakangas wrote:
> Here's another idea that doesn't involve SSI:
> 
> At COMMIT, take a new snapshot and check that the assertion still passes
> with that snapshot. Now, there's a race condition, if another transaction is
> committing at the same time, and performs the same check concurrently. That
> race condition can be eliminated by holding an exclusive lock while running
> the assertion, until commit, effectively allowing the assertion to be
> checked by only one transaction at a time.
> 
> I think that would work, and would be simple, although it wouldn't scale too
> well.

It probably would also be very prone to deadlocks.

Greetings,

Andres Freund

-- Andres Freund                       http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
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