opt: avoid looking up MultiregionConfig for non-multiregion tables

[msirek]

This avoids expensive lookups of the regions in a table's parent database for non-multiregion tables.

Epic: CRDB-18645

Release note: None

[cockroach-teamcity]

This change is 

[msirek]

Avoid expensive assertions in MultiRegionEnumID:

[DrewKimball]

Nice find! I know this is a draft, but probably worth mentioning anyway that you could solve this more simply by making the error global like Yahor did here, since the error is always the same. Do you think any of the other assertions in that file are worth optimizing?

[msirek]

Thanks. The observation here is that there is no point in attempting to look up the multiregion config if we know ahead of time a table is not a multiregion table because none will ever be found. This would apply even if the error were made global.

Reviewable status: complete! 0 of 0 LGTMs obtained

[rytaft]

Reviewed 6 of 6 files at r1, all commit messages.
Reviewable status: complete! 1 of 0 LGTMs obtained (waiting on @msirek and @yuzefovich)

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pkg/sql/opt/table_meta.go line 515 at r1 (raw file):

	}()
	if dbID == 0 || !tm.Table.IsMultiregion() {
		return descpb.SurvivalGoal_ZONE_FAILURE /* regionNames */, false

regionNames -> survivalGoal (or just get rid of this comment -- doesn't seem necessary)

[msirek]

TFTR!
bors r=rytaft

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

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pkg/sql/opt/table_meta.go line 515 at r1 (raw file):

Previously, rytaft (Rebecca Taft) wrote…

regionNames -> survivalGoal (or just get rid of this comment -- doesn't seem necessary)

Removed the comment

[craig]

Build failed (retrying...):

• Bazel Essential CI (Cockroach)

[msirek]

bors r-

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

[craig]

Canceled.

[msirek]

bors r=rytaft

[craig]

Build succeeded:

• Bazel Essential CI (Cockroach)