Re: WIP: generalized index constraints

On Sat, 2009-09-19 at 16:43 -0400, Tom Lane wrote:
> I don't understand why this isn't handled exactly the way unique
> constraints are done now. Frankly, the amount of added complexity you
> propose below is enough to make me want to reject the patch forthwith;
> given that it's going to be a relatively little-used feature, the bugs
> are never going to be out of it completely if we do it like this.

Unique constraints lock the index page while the insert is happening.
How am I supposed to do that, when the conflicting values might be
anywhere in the index (circles have no total order)?

It may sound complex, but it basically boils down to a two stage
process:
1. test for conflicts with concurrently-inserting backends
2. test for conflicts that already exist in the index (dirty or not)

I don't think that it's ridiculously complex. In fact, I think there are
relatively few scenarios that will make any real difference, and those
scenarios can be tested with gdb pretty thoroughly.

Regards,
Jeff Davis