Re: PATCH: use foreign keys to improve join estimates v1

On 04/03/2016 10:06 PM, Simon Riggs wrote:

On 14 March 2016 at 19:42, Tomas Vondra <tomas.vondra@2ndquadrant.com
<mailto:tomas.vondra@2ndquadrant.com>> wrote:

...

I'd like to split this into 2 patches
1) Add FK info to relcache
2) use FK info in planner

Would the credit for this be 1) Tomas, 2) Tomas + David ?

I could split the patch like that, but I don't quite see the point. The two parts will not overlap at all, so not making reviews any simpler. So the only reason for such split seems to be be different credits, but would we actually commit the pieces independently? Not sure about that.

I'd be inclined to see a little more explanatory docs on this.

That's probably a good idea. Do you have any particular place for the docs in mind?

Have we done any tests on planning overhead for cases where multiple
FKs exist?

I have done some benchmarks initially, and haven't measured any noticeable impact. But the code changed since than, so I'll redo that and post some results.