Re: Proposal: GiST constraints

On Tue, 2008-06-10 at 16:59 +0400, Teodor Sigaev wrote:
> > This can be solved by my proposal, but I just don't know how it would
> > apply to something like GIN, for instance. It could replace the unique
> Hmm, your proposal isn't applicable to GIN, because GIN stores a lot of keys for 
> only one value to be indexed.

Right. I can't think of a good reason to constrain a GIN index, but I
think it is possible using this scheme. 

> > being inserted by other concurrent transactions, and those values can
> > be variable in size. What other mechanism do we have to share those
> > variable-sized values among several backends?
> In theory, any indexed value in index (for GiST, after compression) should fit 
> into page at least.
> 

So are you saying we should dedicate one page multiplied by
max_connections in shared memory? It's possible to do it that way, but
we still have to check the heap for visibility information, at least.

Regards,Jeff Davis