opt/opbench: add more cost tests

[justinj]

This commit introduces more costing tests for some scans and sorts.

The plots some some room for improvement on the costing:

Release note: None

[cockroach-teamcity]

This change is 

[RaduBerinde]

Cool graph. I wonder what metric would help bring them more in-line. Maybe avg value size for each column.

Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @RaduBerinde and @rytaft)

[rytaft]

Reviewed 4 of 4 files at r1.
Reviewable status: complete! 2 of 0 LGTMs obtained (waiting on @justinj)

---

pkg/sql/opt/opbench/opbench_test.go, line 552 at r1 (raw file):

				(Table "%s")
				(Cols "$cols")
		  	(HardLimit $rows)

[nit] this isn't lined up

---

pkg/sql/opt/opbench/opbench_test.go, line 583 at r1 (raw file):

		},
	}
}

Seems like there's a lot of common code between makeScanSpec and makeSortSpec -- could some of it be put into a helper function?

---

pkg/sql/opt/opbench/opbench_test.go, line 585 at r1 (raw file):

}

// SortLineitemSpec scans the lineitem table.

scans -> scans and sorts

[justinj]

Thanks! I think avg value size would help, but I think there's an easier win which is tweaking the cost of a single column, since there's a moderately high fixed cost to that. I want to lay down some foundation for talking about the accuracy here before making real changes.

bors r+

Reviewable status: complete! 0 of 0 LGTMs obtained (and 2 stale) (waiting on @rytaft)

---

pkg/sql/opt/opbench/opbench_test.go, line 552 at r1 (raw file):

Previously, rytaft wrote…

[nit] this isn't lined up

Done.

---

pkg/sql/opt/opbench/opbench_test.go, line 583 at r1 (raw file):

Previously, rytaft wrote…

Seems like there's a lot of common code between makeScanSpec and makeSortSpec -- could some of it be put into a helper function?

Pulled out the part that builds the list of columns.

---

pkg/sql/opt/opbench/opbench_test.go, line 585 at r1 (raw file):

Previously, rytaft wrote…

scans -> scans and sorts

Done.

[rytaft]

Reviewed 1 of 1 files at r2.
Reviewable status: complete! 0 of 0 LGTMs obtained (and 2 stale)

[craig]

Build succeeded

• GitHub CI (Cockroach)