This is looking good. I had a few minor comments.

Reviewed 18 of 23 files at r1, all commit messages.
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pkg/sql/inspect_node.go line 38 at r1 (raw file):

	case tree.InspectTable:
		if !params.p.extendedEvalCtx.SessionData().EnableInspectCommand {
			return errors.New("INSPECT TABLE is not enabled by enable_inspect_command")

We have a package for unimlemented errors (see unimplemented.Newf). We should use that here.

pkg/sql/parser/testdata/inspect line 0 at r1 (raw file):
Can we have a testcase where we accept multiple index names? And can we have a test that uses multi-part names for the table?

docs/generated/sql/bnf/inspect_database_stmt.bnf line 2 at r1 (raw file):

inspect_database_stmt ::=
	'INSPECT' 'DATABASE' database_name opt_as_of_clause opt_inspect_options_clause

Since the command isn't ready for prime time yet, we should not have it documented. You can add hidden SQL grammar with the /* SKIP DOC */ comment. Once added, these updates to docs/ should be undone.

pkg/sql/sem/tree/inspect.go line 15 at r1 (raw file):

const (
	// InspectTable describes the INSPECT operation INSPECT TABLE.
	InspectTable = iota

Should we use the InspectType type for these const?

pkg/sql/sessiondatapb/local_only_session_data.proto line 730 at r1 (raw file):

  // mutations), regardless of the table being multi-region.
  bool parallelize_multi_key_lookup_joins_only_on_mr_mutations = 182 [(gogoproto.customname) = "ParallelizeMultiKeyLookupJoinsOnlyOnMRMutations"];
  // EnableInspectCommand controls if a job is initiated when the INSPECT

nit: Is this comment accurate? It's just enables the use of the INSPECT command. It doesn't control if a job is used or not.

pkg/sql/parser/sql.y line 7863 at r1 (raw file):

// %Category: Experimental
// %Text:
// EXPERIMENTAL INSPECT DATABASE <database>

nit: as discussed, lets drop EXPERIMENTAL here

pkg/sql/parser/sql.y line 7873 at r1 (raw file):

  INSPECT DATABASE database_name opt_as_of_clause opt_inspect_options_clause
  {
    $$.val = &tree.Inspect{Typ: tree.InspectDatabase, Database: tree.Name($3), AsOf: $4.asOfClause()}

Should we use the options field? i.e. $5.inspectOptions()

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pkg/sql/inspect_node.go line 38 at r1 (raw file):

Done.

pkg/sql/parser/sql.y line 7873 at r1 (raw file):

Done.

pkg/sql/sem/tree/inspect.go line 15 at r1 (raw file):

Done.

docs/generated/sql/bnf/inspect_database_stmt.bnf line 2 at r1 (raw file):

Done.

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pkg/sql/parser/testdata/inspect line at r1 (raw file):

Done.

@spilchen reviewed 2 of 23 files at r1, 1 of 3 files at r2, 5 of 18 files at r3, 11 of 11 files at r4, all commit messages.
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pkg/sql/inspect_node.go line 38 at r1 (raw file):

nit: I would suggest slightly different wording:

"INSPECT TABLE requires the enable_inspect_command setting to be enabled"
"INSPECT DATABASE requires the enable_inspect_command setting to be enabled"

pkg/sql/parser/testdata/inspect line at r1 (raw file):

Hmm, I still don't see these extra cases. I was thinking of:

• INSPECT TABLE db.schema.t1
• INSPECT TABLE schema.t1 WITH OPTIONS INDEX ( 'i1', 'i2' );

pkg/sql/sem/tree/stmt.go line 1383 at r4 (raw file):

// StatementReturnType implements the Statement interface.
func (*Inspect) StatementReturnType() StatementReturnType { return Rows }

I don't think we should use Rows. I feel like Ack might be better. INSPECT isn't returning the rows with inconsistencies. If validation passes, nothing is returned to the client. The command will just be successful. If there is an inconsistency detected, the command will fail. The user will need to look at the errors table to see what the inconsistency is.

i'll defer to Matt for the final review, just leaving a couple small comments. (not marking as blocking since i'm going OOO, but please address them)

overall lgtm!

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pkg/sql/inspect_node.go line 27 at r5 (raw file):

// Privileges: superuser.
func (p *planner) Inspect(ctx context.Context, n *tree.Inspect) (planNode, error) {
	if err := p.CheckPrivilege(ctx, syntheticprivilege.GlobalPrivilegeObject, privilege.ALL); err != nil {

we should be using the INSPECT privilege here (and update the function comment to mention that too)

pkg/sql/parser/sql.y line 6897 at r5 (raw file):

| import_stmt    // EXTEND WITH HELP: IMPORT
| insert_stmt    // EXTEND WITH HELP: INSERT
| inspect_stmt   { /* SKIP DOC */ }

nit: let's not skip the docs for this. it's going to be a "preview" feature, but those still should get documented: https://www.cockroachlabs.com/docs/stable/cockroachdb-feature-availability

pkg/sql/parser/sql.y line 7826 at r5 (raw file):

// %Help: INSPECT - run checks against databases or tables
// %Category: Experimental

nit: let's remove "experimental" from here. that's an older term that was more restrictive than "preview"

pkg/sql/parser/sql.y line 7834 at r5 (raw file):

inspect_stmt:
  inspect_table_stmt { /* SKIP DOC */ }
| inspect_database_stmt { /* SKIP DOC */ }

nit: let's not skip the docs

pkg/sql/parser/sql.y line 7838 at r5 (raw file):

// %Help: INSPECT TABLE - run inspect checks on a table
// %Category: Experimental

nit: remove "experimental"

@spilchen reviewed 11 of 14 files at r5, all commit messages.
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pkg/sql/parser/sql.y line 6897 at r5 (raw file):

Sorry, this is my bad. I had suggested to skip the docs. The thinking was we would add the docs later. But it'll save a step if we add the docs now.

pkg/sql/parser/testdata/inspect line at r1 (raw file):

I see multiple indexes now. That's good. But I think we are still missing the 3 part name.

@bghal dismissed @spilchen from a discussion.
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pkg/sql/inspect_node.go line 27 at r5 (raw file):

Done.

pkg/sql/sem/tree/stmt.go line 1383 at r4 (raw file):

Done.

pkg/sql/parser/testdata/inspect line at r1 (raw file):

Think I added and deleted those 🙃.

Thanks for doing the revisions.

@spilchen reviewed 1 of 14 files at r5, 4 of 5 files at r6, 10 of 10 files at r7, all commit messages.
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