From c0404a58da643a2997cb57ec6b97d6160d9dc744 Mon Sep 17 00:00:00 2001
From: Spas Bojanov <spas@cockroachlabs.com>
Date: Thu, 1 Oct 2020 12:01:46 +0300
Subject: [PATCH] sql: doctor check for dropped tables

If a table is dropped it should not have a namespace entry.

Release note: none.
---
 pkg/sql/doctor/doctor.go      |  6 ++++++
 pkg/sql/doctor/doctor_test.go | 23 +++++++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/pkg/sql/doctor/doctor.go b/pkg/sql/doctor/doctor.go
index 9d38e7082750..46c649030416 100644
--- a/pkg/sql/doctor/doctor.go
+++ b/pkg/sql/doctor/doctor.go
@@ -176,6 +176,12 @@ func ExamineDescriptors(
 			}
 			continue
 		}
+
+		if desc.Dropped() {
+			fmt.Fprint(stdout, reportMsg(desc, "dropped but namespace entry(s) found: %v", names))
+			problemsFound = true
+		}
+
 		// We delete all pointed descriptors to leave what is missing in the
 		// descriptor table.
 		delete(nMap, row.ID)
diff --git a/pkg/sql/doctor/doctor_test.go b/pkg/sql/doctor/doctor_test.go
index 149224a072ea..800cdc584d89 100644
--- a/pkg/sql/doctor/doctor_test.go
+++ b/pkg/sql/doctor/doctor_test.go
@@ -23,6 +23,7 @@ import (
 	"github.com/cockroachdb/cockroach/pkg/sql/catalog/tabledesc"
 	"github.com/cockroachdb/cockroach/pkg/sql/doctor"
 	"github.com/cockroachdb/cockroach/pkg/sql/types"
+	"github.com/cockroachdb/cockroach/pkg/util/hlc"
 	"github.com/cockroachdb/cockroach/pkg/util/leaktest"
 	"github.com/cockroachdb/cockroach/pkg/util/log"
 	"github.com/cockroachdb/cockroach/pkg/util/protoutil"
@@ -69,6 +70,10 @@ func TestExamineDescriptors(t *testing.T) {
 	defer leaktest.AfterTest(t)()
 	defer log.Scope(t).Close(t)
 
+	droppedValidTableDesc := protoutil.Clone(validTableDesc).(*descpb.Descriptor)
+	descpb.TableFromDescriptor(droppedValidTableDesc, hlc.Timestamp{WallTime: 1}).
+		State = descpb.DescriptorState_DROP
+
 	tests := []struct {
 		descTable      doctor.DescriptorTable
 		namespaceTable doctor.NamespaceTable
@@ -269,6 +274,24 @@ Row(s) [{ParentID:0 ParentSchemaID:0 Name:null}]: NULL value found
 			},
 			expected: `Examining 1 descriptors and 3 namespace entries...
 Database   1: ParentID   0, ParentSchemaID  0, Name 'db': extra draining names found [{ParentID:0 ParentSchemaID:0 Name:db3}]
+`,
+		},
+		{
+			descTable: doctor.DescriptorTable{
+				{ID: 1, DescBytes: toBytes(t, droppedValidTableDesc)},
+				{
+					ID: 2,
+					DescBytes: toBytes(t, &descpb.Descriptor{Union: &descpb.Descriptor_Database{
+						Database: &descpb.DatabaseDescriptor{Name: "db", ID: 2},
+					}}),
+				},
+			},
+			namespaceTable: doctor.NamespaceTable{
+				{NameInfo: descpb.NameInfo{ParentID: 2, ParentSchemaID: 29, Name: "t"}, ID: 1},
+				{NameInfo: descpb.NameInfo{Name: "db"}, ID: 2},
+			},
+			expected: `Examining 2 descriptors and 2 namespace entries...
+   Table   1: ParentID   2, ParentSchemaID 29, Name 't': dropped but namespace entry(s) found: [{2 29 t}]
 `,
 		},
 	}