On Mon, Sep 3, 2018 at 02:53:59PM -0700, Andres Freund wrote: > On 2018-09-03 14:56:28 -0400, Bruce Momjian wrote: > > On Mon, Sep 3, 2018 at 11:42:31AM -0700, Andres Freund wrote: > > > > and JIT, so it doesn't have to be 100% accurate. > > > > > > JIT decision is done after main planning, so we know the cost. > > > > Well, as I remember, we are considering disabling JIT in PG 11 because > > of the use of fixed costs to trigger it. Could executor information > > help decide to use JIT? > > I don't think so. The issues with JIT planning are more that it's > costing is simplistic (for good-ish reason, to avoid increasing the > number of plans), and that there's no caching (lots of infrastructure > work needed).
Uh, yeah, that was my question. If we knew the cost was high before we plan, could we realistically increase the number of plans to avoid the cost-trigger issue? -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + As you are, so once was I. As I am, so you will be. + + Ancient Roman grave inscription +
