opt: add optimizer_min_row_count session setting

[mgartner]

Informs #64570
Informs #130201

Release note (sql change): The optimizer_min_row_count session setting
has been added which sets a lower bound on row count estimates for
relational expressions during query planning. A value of zero, which is
the default, indicates no lower bound. Note that if this is set to a
value greater than zero, a row count of zero can still be estimated for
expressions with a cardinality of zero, e.g., for a contradictory
filter. Setting this to a value higher than 0, such as 1, may yield
better query plans in some cases, such as when statistics are frequently
stale and inaccurate.

[cockroach-teamcity]

This change is 

[michae2]

Great idea to make it configurable. This is nice!

Reviewed 25 of 25 files at r1, all commit messages.
Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @DrewKimball and @rytaft)

[mw5h]

Reviewed 25 of 25 files at r1, all commit messages.
Reviewable status: complete! 2 of 0 LGTMs obtained (waiting on @DrewKimball, @mgartner, and @rytaft)

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pkg/sql/opt/memo/statistics_builder_test.go line 115 at r1 (raw file):

		relProps.NotNullCols = cs.ExtractNotNullCols(ctx, &evalCtx)
		s := relProps.Statistics()
		const minRowCount = 0

Worth re-running this test with minRowCount = 1?

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pkg/sql/opt/memo/statistics_builder.go line 842 at r1 (raw file):

func (sb *statisticsBuilder) buildScan(scan *ScanExpr, relProps *props.Relational) {
	s := relProps.Statistics()
	if zeroCardinality := s.Init(relProps, sb.minRowCount); zeroCardinality {

Boilerplate like this is great opportunity to refactor. If the Go designers thought highly enough of us to think we could use macros without hurting ourselves, this would be an excellent use, but we'll have to make do with passing function pointers around.

I know you're on deadline, so fine if you don't want to deal with this now.

[mgartner]

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

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pkg/sql/opt/memo/statistics_builder_test.go line 115 at r1 (raw file):

Previously, mw5h (Matt White) wrote…

Worth re-running this test with minRowCount = 1?

The coverage of this test is minimal, so I don't think we get much from this. I think the datadriven tests I added are sufficient.

[mgartner]

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

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pkg/sql/opt/memo/statistics_builder.go line 842 at r1 (raw file):

Previously, mw5h (Matt White) wrote…

Boilerplate like this is great opportunity to refactor. If the Go designers thought highly enough of us to think we could use macros without hurting ourselves, this would be an excellent use, but we'll have to make do with passing function pointers around.

I know you're on deadline, so fine if you don't want to deal with this now.

Talked in Slack - we'll keep as-is for now, but we can also consider refactoring this in the future!

[mgartner]

TFTRs!

bors r+

[craig]

Build succeeded:

• docker_image_amd64
• unit_tests
• local_roachtest
• linux_amd64_build
• acceptance
• lint
• check_generated_code
• examples_orms
• windows_build
• local_roachtest_fips
• linux_amd64_fips_build
• macos_arm64_build
• linux_arm64_build
• macos_amd64_build

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