sql: Reorder show ranges output to be clearer

The output of show ranges had column orderings that at a quick glance
could lead to users making the wrong conclusions about their
partitioning setup. This PR adjusts the columns and adds more readily
accessible information about the lease_holder node's locality.

Fixes #40467.

Release note (sql change): Reorder columns in show ranges output

pkg/sql/delegate/show_ranges.go

@@ -42,10 +42,12 @@ func (d *delegator) delegateShowRanges(n *tree.ShowRanges) (tree.Statement, erro
 			END AS end_key,
 			range_id,
 			range_size / 1000000 as range_size_mb,
-			replicas,
 			lease_holder,
-			replica_localities,
+    	gossip_nodes.locality as lease_holder_locality,
+			replicas,
+			replica_localities
 		FROM %[1]s.crdb_internal.ranges AS r
+	  LEFT JOIN crdb_internal.gossip_nodes ON lease_holder = node_id
 		WHERE database_name=%[2]s
 		ORDER BY table_name, r.start_key
 		`
@@ -71,10 +73,12 @@ SELECT
   CASE WHEN r.end_key >= x'%s' THEN NULL ELSE crdb_internal.pretty_key(r.end_key, 2) END AS end_key,
   range_id,
   range_size / 1000000 as range_size_mb,
-  replicas,
   lease_holder,
+  gossip_nodes.locality as lease_holder_locality,
+  replicas,
   replica_localities
 FROM crdb_internal.ranges AS r
+LEFT JOIN crdb_internal.gossip_nodes ON lease_holder = node_id
 WHERE (r.start_key < x'%s')
   AND (r.end_key   > x'%s') ORDER BY r.start_key
 `,

pkg/sql/show_ranges_test.go

@@ -36,19 +36,29 @@ func TestShowRangesWithLocality(t *testing.T) {
 	sqlDB.Exec(t, `CREATE TABLE t (x INT PRIMARY KEY)`)
 	sqlDB.Exec(t, `ALTER TABLE t SPLIT AT SELECT i FROM generate_series(0, 20) AS g(i)`)
 
-	const replicasColIdx = 4
-	const localitiesColIdx = 6
+	const leaseHolderIdx = 0
+	const leaseHolderLocalityIdx = 1
+	const replicasColIdx = 2
+	const localitiesColIdx = 3
 	replicas := make([]int, 3)
 
-	result := sqlDB.QueryStr(t, `SHOW RANGES FROM TABLE t`)
+	q := `SELECT lease_holder, lease_holder_locality, replicas, replica_localities from [SHOW RANGES FROM TABLE t]`
+	result := sqlDB.QueryStr(t, q)
+	// Because StartTestCluster changes the locality no matter what the
+	// arguments are, we expect whatever the test server sets up.
 	for _, row := range result {
+		// Verify the leaseholder localities.
+		leaseHolder := row[leaseHolderIdx]
+		leaseHolderLocalityExpected := fmt.Sprintf(`region=test,dc=dc%s`, leaseHolder)
+		if row[leaseHolderLocalityIdx] != leaseHolderLocalityExpected {
+			t.Fatalf("expected %s found %s", leaseHolderLocalityExpected, row[leaseHolderLocalityIdx])
+		}
+
+		// Verify the replica localities.
 		_, err := fmt.Sscanf(row[replicasColIdx], "{%d,%d,%d}", &replicas[0], &replicas[1], &replicas[2])
 		if err != nil {
 			t.Fatal(err)
 		}
-
-		// Because StartTestCluster changes the locality no matter what the
-		// arguments are, we expect whatever the test server sets up.
 		var builder strings.Builder
 		builder.WriteString("{")
 		for i, replica := range replicas {
@@ -59,7 +69,6 @@ func TestShowRangesWithLocality(t *testing.T) {
 		}
 		builder.WriteString("}")
 		expected := builder.String()
-
 		if row[localitiesColIdx] != expected {
 			t.Fatalf("expected %s found %s", expected, row[localitiesColIdx])
 		}