func TestDropIndex(t *testing.T) {
	defer leaktest.AfterTest(t)()
	params, _ := createTestServerParams()
	s, sqlDB, kvDB := serverutils.StartServer(t, params)
	defer s.Stopper().Stop()

	if _, err := sqlDB.Exec(`
CREATE DATABASE t;
CREATE TABLE t.kv (k CHAR PRIMARY KEY, v CHAR);
CREATE INDEX foo on t.kv (v);
INSERT INTO t.kv VALUES ('c', 'e'), ('a', 'c'), ('b', 'd');
`); err != nil {
		t.Fatal(err)
	}

	tableDesc := sqlbase.GetTableDescriptor(kvDB, "t", "kv")

	status, i, err := tableDesc.FindIndexByName("foo")
	if err != nil {
		t.Fatal(err)
	}
	if status != sqlbase.DescriptorActive {
		t.Fatal("Index 'foo' is not active.")
	}
	indexPrefix := sqlbase.MakeIndexKeyPrefix(tableDesc.ID, tableDesc.Indexes[i].ID)

	indexStartKey := roachpb.Key(indexPrefix)
	indexEndKey := indexStartKey.PrefixEnd()
	if kvs, err := kvDB.Scan(indexStartKey, indexEndKey, 0); err != nil {
		t.Fatal(err)
	} else if l := 3; len(kvs) != l {
		t.Fatalf("expected %d key value pairs, but got %d", l, len(kvs))
	}

	if _, err := sqlDB.Exec(`DROP INDEX [email protected]`); err != nil {
		t.Fatal(err)
	}

	if kvs, err := kvDB.Scan(indexStartKey, indexEndKey, 0); err != nil {
		t.Fatal(err)
	} else if l := 0; len(kvs) != l {
		t.Fatalf("expected %d key value pairs, but got %d", l, len(kvs))
	}

	tableDesc = sqlbase.GetTableDescriptor(kvDB, "t", "kv")

	if _, _, err := tableDesc.FindIndexByName("foo"); err == nil {
		t.Fatalf("table descriptor still contains index after index is dropped")
	}
	if err != nil {
		t.Fatal(err)
	}
}

// Test that table names are not treated as case sensitive by the name cache.
func TestTableNameNotCaseSensitive(t *testing.T) {
	defer leaktest.AfterTest(t)()
	s, sqlDB, kvDB, cleanup := sqlutils.SetupServer(t)
	defer cleanup()
	leaseManager := s.LeaseManager().(*LeaseManager)

	if _, err := sqlDB.Exec(`
CREATE DATABASE t;
CREATE TABLE t.test (k CHAR PRIMARY KEY, v CHAR);
`); err != nil {
		t.Fatal(err)
	}

	// Populate the name cache.
	if _, err := sqlDB.Exec("SELECT * FROM t.test;"); err != nil {
		t.Fatal(err)
	}

	tableDesc := sqlbase.GetTableDescriptor(kvDB, "t", "test")

	// Check that we can get the table by a different name.
	lease := leaseManager.tableNames.get(tableDesc.ParentID, "tEsT", s.Clock())
	if lease == nil {
		t.Fatalf("no name cache entry")
	}
	if err := leaseManager.Release(lease); err != nil {
		t.Fatal(err)
	}
}

// Test that abruptly closing a pgwire connection releases all leases held by
// that session.
func TestPGWireConnectionCloseReleasesLeases(t *testing.T) {
	defer leaktest.AfterTest(t)()
	s, _, kvDB := serverutils.StartServer(t, base.TestServerArgs{})
	defer s.Stopper().Stop()
	url, cleanupConn := sqlutils.PGUrl(t, s.ServingAddr(), security.RootUser, "SetupServer")
	defer cleanupConn()
	conn, err := pq.Open(url.String())
	if err != nil {
		t.Fatal(err)
	}
	ex := conn.(driver.Execer)
	if _, err := ex.Exec("CREATE DATABASE test", nil); err != nil {
		t.Fatal(err)
	}
	if _, err := ex.Exec("CREATE TABLE test.t (i INT PRIMARY KEY)", nil); err != nil {
		t.Fatal(err)
	}
	// Start a txn so leases are accumulated by queries.
	if _, err := ex.Exec("BEGIN", nil); err != nil {
		t.Fatal(err)
	}
	// Get a table lease.
	if _, err := ex.Exec("SELECT * FROM test.t", nil); err != nil {
		t.Fatal(err)
	}
	// Abruptly close the connection.
	if err := conn.Close(); err != nil {
		t.Fatal(err)
	}
	// Verify that there are no leases held.
	tableDesc := sqlbase.GetTableDescriptor(kvDB, "test", "t")
	lm := s.LeaseManager().(*LeaseManager)
	// Looking for a table state validates that there used to be a lease on the
	// table.
	ts := lm.findTableState(tableDesc.ID, false /* create */)
	if ts == nil {
		t.Fatal("table state not found")
	}
	ts.mu.Lock()
	leases := ts.active.data
	ts.mu.Unlock()
	if len(leases) != 1 {
		t.Fatalf("expected one lease, found: %d", len(leases))
	}
	// Wait for the lease to be released.
	util.SucceedsSoon(t, func() error {
		ts.mu.Lock()
		refcount := ts.active.data[0].refcount
		ts.mu.Unlock()
		if refcount != 0 {
			return errors.Errorf(
				"expected lease to be unused, found refcount: %d", refcount)
		}
		return nil
	})
}

// Test that we fail to lease a table that was marked for deletion.
func TestCantLeaseDeletedTable(testingT *testing.T) {
	defer leaktest.AfterTest(testingT)()

	var mu sync.Mutex
	clearSchemaChangers := false

	ctx, _ := createTestServerContext()
	ctx.TestingKnobs = base.TestingKnobs{
		SQLExecutor: &csql.ExecutorTestingKnobs{
			SyncSchemaChangersFilter: func(tscc csql.TestingSchemaChangerCollection) {
				mu.Lock()
				defer mu.Unlock()
				if clearSchemaChangers {
					tscc.ClearSchemaChangers()
				}
			},
		},
		SQLSchemaChangeManager: &csql.SchemaChangeManagerTestingKnobs{
			AsyncSchemaChangerExecNotification: schemaChangeManagerDisabled,
		},
	}

	t := newLeaseTest(testingT, &ctx)
	defer t.cleanup()

	sql := `
CREATE DATABASE test;
CREATE TABLE test.t(a INT PRIMARY KEY);
`
	_, err := t.db.Exec(sql)
	if err != nil {
		t.Fatal(err)
	}

	// Block schema changers so that the table we're about to DROP is not actually
	// dropped; it will be left in a "deleted" state.
	mu.Lock()
	clearSchemaChangers = true
	mu.Unlock()

	// DROP the table
	_, err = t.db.Exec(`DROP TABLE test.t`)
	if err != nil {
		t.Fatal(err)
	}

	// Make sure we can't get a lease on the descriptor.
	tableDesc := sqlbase.GetTableDescriptor(t.kvDB, "test", "t")
	// try to acquire at a bogus version to make sure we don't get back a lease we
	// already had.
	_, err = t.acquire(1, tableDesc.ID, tableDesc.Version+1)
	if !testutils.IsError(err, "table is being deleted") {
		t.Fatalf("got a different error than expected: %s", err)
	}
}

// TestAddingFKs checks the behavior of a table in the non-public `ADD` state.
// Being non-public, it should not be visible to clients, and is therefore
// assumed to be empty (e.g. by foreign key checks), since no one could have
// written to it yet.
func TestAddingFKs(t *testing.T) {
	defer leaktest.AfterTest(t)()

	params, _ := createTestServerParams()
	s, sqlDB, kvDB := serverutils.StartServer(t, params)
	defer s.Stopper().Stop()

	if _, err := sqlDB.Exec(`
		CREATE DATABASE t;
		CREATE TABLE t.products (id INT PRIMARY KEY);
		INSERT INTO t.products VALUES (1), (2);
		CREATE TABLE t.orders (id INT PRIMARY KEY, product INT REFERENCES t.products, INDEX (product));
	`); err != nil {
		t.Fatal(err)
	}

	// Step the referencing table back to the ADD state.
	ordersDesc := sqlbase.GetTableDescriptor(kvDB, "t", "orders")
	ordersDesc.State = sqlbase.TableDescriptor_ADD
	ordersDesc.Version++
	if err := kvDB.Put(
		sqlbase.MakeDescMetadataKey(ordersDesc.ID),
		sqlbase.WrapDescriptor(ordersDesc),
	); err != nil {
		t.Fatal(err)
	}

	// Generally a referenced table needs to lookup referencing tables to check
	// FKs during delete operations, but referencing tables in the ADD state are
	// given special treatment.
	if _, err := sqlDB.Exec(`DELETE FROM t.products`); err != nil {
		t.Fatal(err)
	}

	// Client should not see the orders table.
	if _, err := sqlDB.Exec(
		`SELECT * FROM t.orders`,
	); !testutils.IsError(err, "table is being added") {
		t.Fatal(err)
	}
}

// Tests that a name cache entry with by an expired lease is not returned.
func TestNameCacheEntryDoesntReturnExpiredLease(t *testing.T) {
	defer leaktest.AfterTest(t)()
	s, sqlDB, kvDB, cleanup := sqlutils.SetupServer(t)
	defer cleanup()
	leaseManager := s.LeaseManager().(*LeaseManager)

	if _, err := sqlDB.Exec(`
CREATE DATABASE t;
CREATE TABLE t.test (k CHAR PRIMARY KEY, v CHAR);
`); err != nil {
		t.Fatal(err)
	}

	// Populate the name cache.
	if _, err := sqlDB.Exec("SELECT * FROM t.test;"); err != nil {
		t.Fatal(err)
	}

	tableDesc := sqlbase.GetTableDescriptor(kvDB, "t", "test")

	// Check the assumptions this tests makes: that there is a cache entry
	// (with a valid lease).
	lease := leaseManager.tableNames.get(tableDesc.ParentID, "test", s.Clock())
	if lease == nil {
		t.Fatalf("no name cache entry")
	}
	if err := leaseManager.Release(lease); err != nil {
		t.Fatal(err)
	}
	// Advance the clock to expire the lease.
	s.Clock().SetMaxOffset(10 * LeaseDuration)
	s.Clock().Update(s.Clock().Now().Add(int64(2*LeaseDuration), 0))

	// Check the the name no longer resolves.
	if leaseManager.tableNames.get(tableDesc.ParentID, "test", s.Clock()) != nil {
		t.Fatalf("name resolves when it shouldn't")
	}
}

// TestAcquireFreshestFromStoreRaces runs
// LeaseManager.acquireFreshestFromStore() in parallel to test for races.
func TestAcquireFreshestFromStoreRaces(t *testing.T) {
	defer leaktest.AfterTest(t)()
	s, db, kvDB := serverutils.StartServer(t, base.TestServerArgs{})
	defer s.Stopper().Stop()
	leaseManager := s.LeaseManager().(*LeaseManager)

	if _, err := db.Exec(`
CREATE DATABASE t;
CREATE TABLE t.test (k CHAR PRIMARY KEY, v CHAR);
`); err != nil {
		t.Fatal(err)
	}

	tableDesc := sqlbase.GetTableDescriptor(kvDB, "t", "test")

	var wg sync.WaitGroup
	numRoutines := 10
	wg.Add(numRoutines)
	for i := 0; i < numRoutines; i++ {
		go func() {
			defer wg.Done()
			err := kvDB.Txn(func(txn *client.Txn) error {
				lease, err := leaseManager.acquireFreshestFromStore(txn, tableDesc.ID)
				if err != nil {
					return err
				}
				if err := leaseManager.Release(lease); err != nil {
					return err
				}
				return nil
			})
			if err != nil {
				t.Error(err)
			}
		}()
	}
	wg.Wait()
}

func TestOperationsWithColumnMutation(t *testing.T) {
	defer leaktest.AfterTest(t)()
	// The descriptor changes made must have an immediate effect
	// so disable leases on tables.
	defer csql.TestDisableTableLeases()()
	// Disable external processing of mutations.
	params, _ := createTestServerParams()
	params.Knobs.SQLSchemaChangeManager = &csql.SchemaChangeManagerTestingKnobs{
		AsyncSchemaChangerExecNotification: schemaChangeManagerDisabled,
	}
	server, sqlDB, kvDB := serverutils.StartServer(t, params)
	defer server.Stopper().Stop()

	if _, err := sqlDB.Exec(`
CREATE DATABASE t;
CREATE TABLE t.test (k CHAR PRIMARY KEY, v CHAR, i CHAR DEFAULT 'i');
`); err != nil {
		t.Fatal(err)
	}

	// read table descriptor
	tableDesc := sqlbase.GetTableDescriptor(kvDB, "t", "test")

	mTest := mutationTest{
		T:         t,
		kvDB:      kvDB,
		sqlDB:     sqlDB,
		tableDesc: tableDesc,
	}

	starQuery := `SELECT * FROM t.test`
	// Run the tests for both states.
	for _, state := range []sqlbase.DescriptorMutation_State{sqlbase.DescriptorMutation_DELETE_ONLY, sqlbase.DescriptorMutation_WRITE_ONLY} {
		// Init table to start state.
		if _, err := sqlDB.Exec(`TRUNCATE TABLE t.test`); err != nil {
			t.Fatal(err)
		}
		initRows := [][]string{{"a", "z", "q"}}
		for _, row := range initRows {
			if _, err := sqlDB.Exec(`INSERT INTO t.test VALUES ($1, $2, $3)`, row[0], row[1], row[2]); err != nil {
				t.Fatal(err)
			}
		}
		// Check that the table only contains the initRows.
		_ = mTest.checkQueryResponse(starQuery, initRows)

		// Add column "i" as a mutation.
		mTest.writeColumnMutation("i", sqlbase.DescriptorMutation{State: state})
		// A direct read of column "i" fails.
		if _, err := sqlDB.Query(`SELECT i FROM t.test`); err == nil {
			t.Fatalf("Read succeeded despite column being in %v state", sqlbase.DescriptorMutation{State: state})
		}
		// The table only contains columns "k" and "v".
		_ = mTest.checkQueryResponse(starQuery, [][]string{{"a", "z"}})

		// The column backfill uses Put instead of CPut because it depends on
		// an INSERT of a column in the WRITE_ONLY state failing. These two
		// tests guarantee that.

		// Inserting a row into the table while specifying column "i" results in an error.
		if _, err := sqlDB.Exec(`INSERT INTO t.test (k, v, i) VALUES ('b', 'y', 'i')`); !testutils.IsError(err, `column "i" does not exist`) {
			t.Fatal(err)
		}
		// Repeating the same without specifying the columns results in a different error.
		if _, err := sqlDB.Exec(`INSERT INTO t.test VALUES ('b', 'y', 'i')`); !testutils.IsError(err, "INSERT error: table t.test has 2 columns but 3 values were supplied") {
			t.Fatal(err)
		}
		// Make column "i" live so that it is read.
		mTest.makeMutationsActive()
		// Check that we can read all the rows and columns.
		_ = mTest.checkQueryResponse(starQuery, initRows)

		var afterInsert, afterUpdate, afterDelete [][]string
		if state == sqlbase.DescriptorMutation_DELETE_ONLY {
			// The default value of "i" for column "i" is not written.
			afterInsert = [][]string{{"a", "z", "q"}, {"c", "x", "NULL"}}
			// Update is a noop for column "i".
			afterUpdate = [][]string{{"a", "u", "q"}, {"c", "x", "NULL"}}
			// Delete also deletes column "i".
			afterDelete = [][]string{{"c", "x", "NULL"}}
		} else {
			// The default value of "i" for column "i" is written.
			afterInsert = [][]string{{"a", "z", "q"}, {"c", "x", "i"}}
			// Update is a noop for column "i".
			afterUpdate = [][]string{{"a", "u", "q"}, {"c", "x", "i"}}
			// Delete also deletes column "i".
			afterDelete = [][]string{{"c", "x", "i"}}
		}
		// Make column "i" a mutation.
		mTest.writeColumnMutation("i", sqlbase.DescriptorMutation{State: state})
		// Insert a row into the table.
		if _, err := sqlDB.Exec(`INSERT INTO t.test VALUES ('c', 'x')`); err != nil {
			t.Fatal(err)
		}
		// Make column "i" live so that it is read.
		mTest.makeMutationsActive()
		// Notice that the default value of "i" is only written when the
		// descriptor is in the WRITE_ONLY state.
		_ = mTest.checkQueryResponse(starQuery, afterInsert)

//.........这里部分代码省略.........

func TestTableReader(t *testing.T) {
	defer leaktest.AfterTest(t)()

	_, sqlDB, kvDB, cleanup := sqlutils.SetupServer(t)
	defer cleanup()

	if _, err := sqlDB.Exec(`
		CREATE DATABASE test;
		CREATE TABLE test.t (a INT PRIMARY KEY, b INT, c INT, d INT, INDEX bc (b, c));
		INSERT INTO test.t VALUES (1, 10, 11, 12), (2, 20, 21, 22), (3, 30, 31, 32);
		INSERT INTO test.t VALUES (4, 60, 61, 62), (5, 50, 51, 52), (6, 40, 41, 42);
	`); err != nil {
		t.Fatal(err)
	}

	td := sqlbase.GetTableDescriptor(kvDB, "test", "t")

	ts := TableReaderSpec{
		Table:         *td,
		IndexIdx:      0,
		Reverse:       false,
		Spans:         nil,
		Filter:        Expression{Expr: "$2 != 21"}, // c != 21
		OutputColumns: []uint32{0, 3},               // a, d
	}

	txn := client.NewTxn(context.Background(), *kvDB)

	out := &testingReceiver{}
	tr, err := newTableReader(&ts, txn, out, parser.EvalContext{})
	if err != nil {
		t.Fatal(err)
	}
	tr.run()
	if out.err != nil {
		t.Fatal(out.err)
	}
	if !out.closed {
		t.Fatalf("output rowReceiver not closed")
	}
	expected := "[[1 12] [3 32] [4 62] [5 52] [6 42]]"
	if fmt.Sprintf("%s", out.rows) != expected {
		t.Errorf("invalid results: %s, expected %s'", out.rows, expected)
	}

	// Read using the bc index
	var span roachpb.Span
	span.Key = roachpb.Key(sqlbase.MakeIndexKeyPrefix(td.ID, td.Indexes[0].ID))
	span.EndKey = append(span.Key, encoding.EncodeVarintAscending(nil, 50)...)

	ts = TableReaderSpec{
		Table:         *td,
		IndexIdx:      1,
		Reverse:       true,
		Spans:         []TableReaderSpan{{Span: span}},
		Filter:        Expression{Expr: "$1 != 30"}, // b != 30
		OutputColumns: []uint32{0, 2},               // a, c
	}
	out = &testingReceiver{}
	tr, err = newTableReader(&ts, txn, out, parser.EvalContext{})
	if err != nil {
		t.Fatal(err)
	}
	tr.run()
	if out.err != nil {
		t.Fatal(out.err)
	}
	if !out.closed {
		t.Fatalf("output rowReceiver not closed")
	}
	expected = "[[6 41] [2 21] [1 11]]"
	if fmt.Sprintf("%s", out.rows) != expected {
		t.Errorf("invalid results: %s, expected %s'", out.rows, expected)
	}
}

func TestDropTable(t *testing.T) {
	defer leaktest.AfterTest(t)()
	s, sqlDB, kvDB := setup(t)
	defer cleanup(s, sqlDB)

	if _, err := sqlDB.Exec(`
CREATE DATABASE t;
CREATE TABLE t.kv (k CHAR PRIMARY KEY, v CHAR);
INSERT INTO t.kv VALUES ('c', 'e'), ('a', 'c'), ('b', 'd');
`); err != nil {
		t.Fatal(err)
	}

	tableDesc := sqlbase.GetTableDescriptor(kvDB, "t", "kv")
	nameKey := sqlbase.MakeNameMetadataKey(keys.MaxReservedDescID+1, "kv")
	gr, err := kvDB.Get(nameKey)

	if err != nil {
		t.Fatal(err)
	}

	if !gr.Exists() {
		t.Fatalf("Name entry %q does not exist", nameKey)
	}

	descKey := sqlbase.MakeDescMetadataKey(sqlbase.ID(gr.ValueInt()))

	// Add a zone config for the table.
	cfg := config.DefaultZoneConfig()
	buf, err := protoutil.Marshal(&cfg)
	if err != nil {
		t.Fatal(err)
	}
	if _, err := sqlDB.Exec(`INSERT INTO system.zones VALUES ($1, $2)`, tableDesc.ID, buf); err != nil {
		t.Fatal(err)
	}

	zoneKey := sqlbase.MakeZoneKey(tableDesc.ID)
	if gr, err := kvDB.Get(zoneKey); err != nil {
		t.Fatal(err)
	} else if !gr.Exists() {
		t.Fatalf("zone config entry not found")
	}

	tablePrefix := keys.MakeTablePrefix(uint32(tableDesc.ID))
	tableStartKey := roachpb.Key(tablePrefix)
	tableEndKey := tableStartKey.PrefixEnd()
	if kvs, err := kvDB.Scan(tableStartKey, tableEndKey, 0); err != nil {
		t.Fatal(err)
	} else if l := 6; len(kvs) != l {
		t.Fatalf("expected %d key value pairs, but got %d", l, len(kvs))
	}

	if _, err := sqlDB.Exec(`DROP TABLE t.kv`); err != nil {
		t.Fatal(err)
	}

	// Test that deleted table cannot be used. This prevents regressions where
	// name -> descriptor ID caches might make this statement erronously work.
	if _, err := sqlDB.Exec(`SELECT * FROM t.kv`); !testutils.IsError(err, `table "t.kv" does not exist`) {
		t.Fatalf("different error than expected: %s", err)
	}

	if kvs, err := kvDB.Scan(tableStartKey, tableEndKey, 0); err != nil {
		t.Fatal(err)
	} else if l := 0; len(kvs) != l {
		t.Fatalf("expected %d key value pairs, but got %d", l, len(kvs))
	}

	if gr, err := kvDB.Get(descKey); err != nil {
		t.Fatal(err)
	} else if gr.Exists() {
		t.Fatalf("table descriptor still exists after the table is dropped")
	}

	if gr, err := kvDB.Get(nameKey); err != nil {
		t.Fatal(err)
	} else if gr.Exists() {
		t.Fatalf("table namekey still exists after the table is dropped")
	}

	if gr, err := kvDB.Get(zoneKey); err != nil {
		t.Fatal(err)
	} else if gr.Exists() {
		t.Fatalf("zone config entry still exists after the table is dropped")
	}
}

func TestPurgeOldLeases(t *testing.T) {
	defer leaktest.AfterTest(t)()
	// We're going to block gossip so it doesn't come randomly and clear up the
	// leases we're artificially setting up.
	gossipSem := make(chan struct{}, 1)
	serverParams := testingshim.TestServerParams{
		Knobs: base.TestingKnobs{
			SQLLeaseManager: &LeaseManagerTestingKnobs{
				GossipUpdateEvent: func(cfg config.SystemConfig) {
					gossipSem <- struct{}{}
					<-gossipSem
				},
			},
		},
	}
	s, db, kvDB, cleanup := sqlutils.SetupServerWithParams(t, serverParams)
	defer cleanup()
	leaseManager := s.LeaseManager().(*LeaseManager)
	// Block gossip.
	gossipSem <- struct{}{}
	defer func() {
		// Unblock gossip.
		<-gossipSem
	}()

	if _, err := db.Exec(`
CREATE DATABASE t;
CREATE TABLE t.test (k CHAR PRIMARY KEY, v CHAR);
`); err != nil {
		t.Fatal(err)
	}

	tableDesc := sqlbase.GetTableDescriptor(kvDB, "t", "test")

	var leases []*LeaseState
	err := kvDB.Txn(func(txn *client.Txn) error {
		for i := 0; i < 3; i++ {
			lease, err := leaseManager.acquireFreshestFromStore(txn, tableDesc.ID)
			if err != nil {
				t.Fatal(err)
			}
			leases = append(leases, lease)
			if err := leaseManager.Release(lease); err != nil {
				t.Fatal(err)
			}
		}
		return nil
	})
	if err != nil {
		t.Fatal(err)
	}
	ts := leaseManager.findTableState(tableDesc.ID, false, nil)
	if numLeases := getNumLeases(ts); numLeases != 3 {
		t.Fatalf("found %d leases instead of 3", numLeases)
	}

	if err := ts.purgeOldLeases(
		kvDB, false, 1 /* minVersion */, leaseManager.LeaseStore); err != nil {
		t.Fatal(err)
	}

	if numLeases := getNumLeases(ts); numLeases != 1 {
		t.Fatalf("found %d leases instead of 1", numLeases)
	}
	ts.mu.Lock()
	correctLease := ts.active.data[0] == leases[2]
	ts.mu.Unlock()
	if !correctLease {
		t.Fatalf("wrong lease survived purge")
	}
}

func TestTableReader(t *testing.T) {
	defer leaktest.AfterTest(t)()

	_, sqlDB, kvDB, cleanup := sqlutils.SetupServer(t)
	defer cleanup()

	// Create a table where each row is:
	//
	//  |     a    |     b    |         sum         |         s           |
	//  |-----------------------------------------------------------------|
	//  | rowId/10 | rowId%10 | rowId/10 + rowId%10 | IntToEnglish(rowId) |

	aFn := func(row int) parser.Datum {
		return parser.NewDInt(parser.DInt(row / 10))
	}
	bFn := func(row int) parser.Datum {
		return parser.NewDInt(parser.DInt(row % 10))
	}
	sumFn := func(row int) parser.Datum {
		return parser.NewDInt(parser.DInt(row/10 + row%10))
	}

	sqlutils.CreateTable(t, sqlDB, "t",
		"a INT, b INT, sum INT, s STRING, PRIMARY KEY (a,b), INDEX bs (b,s)",
		99,
		sqlutils.ToRowFn(aFn, bFn, sumFn, sqlutils.RowEnglishFn))

	td := sqlbase.GetTableDescriptor(kvDB, "test", "t")

	makeIndexSpan := func(start, end int) TableReaderSpan {
		var span roachpb.Span
		prefix := roachpb.Key(sqlbase.MakeIndexKeyPrefix(td.ID, td.Indexes[0].ID))
		span.Key = append(prefix, encoding.EncodeVarintAscending(nil, int64(start))...)
		span.EndKey = append(span.EndKey, prefix...)
		span.EndKey = append(span.EndKey, encoding.EncodeVarintAscending(nil, int64(end))...)
		return TableReaderSpan{Span: span}
	}

	testCases := []struct {
		spec     TableReaderSpec
		expected string
	}{
		{
			spec: TableReaderSpec{
				Filter:        Expression{Expr: "$2 < 5 AND $1 != 3"}, // sum < 5 && b != 3
				OutputColumns: []uint32{0, 1},
			},
			expected: "[[0 1] [0 2] [0 4] [1 0] [1 1] [1 2] [2 0] [2 1] [2 2] [3 0] [3 1] [4 0]]",
		},
		{
			spec: TableReaderSpec{
				Filter:        Expression{Expr: "$2 < 5 AND $1 != 3"},
				OutputColumns: []uint32{3}, // s
				HardLimit:     4,
			},
			expected: "[['one'] ['two'] ['four'] ['one-zero']]",
		},
		{
			spec: TableReaderSpec{
				IndexIdx:      1,
				Reverse:       true,
				Spans:         []TableReaderSpan{makeIndexSpan(4, 6)},
				Filter:        Expression{Expr: "$0 < 3"}, // sum < 8
				OutputColumns: []uint32{0, 1},
				SoftLimit:     1,
			},
			expected: "[[2 5] [1 5] [0 5] [2 4] [1 4] [0 4]]",
		},
	}

	for _, c := range testCases {
		ts := c.spec
		ts.Table = *td

		txn := client.NewTxn(context.Background(), *kvDB)

		out := &RowBuffer{}
		tr, err := newTableReader(&ts, txn, out, &parser.EvalContext{})
		if err != nil {
			t.Fatal(err)
		}
		tr.Run(nil)
		if out.err != nil {
			t.Fatal(out.err)
		}
		if !out.closed {
			t.Fatalf("output RowReceiver not closed")
		}
		if result := out.rows.String(); result != c.expected {
			t.Errorf("invalid results: %s, expected %s'", result, c.expected)
		}
	}
}

// TestSchemaChangeCommandsWithPendingMutations tests how schema change
// commands behave when they are referencing schema elements that are
// mutations that are not yet live.
func TestSchemaChangeCommandsWithPendingMutations(t *testing.T) {
	defer leaktest.AfterTest(t)()
	// The descriptor changes made must have an immediate effect
	// so disable leases on tables.
	defer csql.TestDisableTableLeases()()
	// Disable external processing of mutations.
	params, _ := createTestServerParams()
	params.Knobs.SQLSchemaChangeManager = &csql.SchemaChangeManagerTestingKnobs{
		AsyncSchemaChangerExecNotification: schemaChangeManagerDisabled,
	}
	server, sqlDB, kvDB := serverutils.StartServer(t, params)
	defer server.Stopper().Stop()

	if _, err := sqlDB.Exec(`
CREATE DATABASE t;
CREATE TABLE t.test (a CHAR PRIMARY KEY, b CHAR, c CHAR, INDEX foo (c));
`); err != nil {
		t.Fatal(err)
	}

	// Read table descriptor
	tableDesc := sqlbase.GetTableDescriptor(kvDB, "t", "test")

	mt := mutationTest{
		T:         t,
		kvDB:      kvDB,
		sqlDB:     sqlDB,
		tableDesc: tableDesc,
	}

	// Test CREATE INDEX in the presence of mutations.

	// Add index DROP mutation "foo""
	mt.writeIndexMutation("foo", sqlbase.DescriptorMutation{Direction: sqlbase.DescriptorMutation_DROP})
	if _, err := sqlDB.Exec(`CREATE INDEX foo ON t.test (c)`); !testutils.IsError(err, `index "foo" being dropped, try again later`) {
		t.Fatal(err)
	}
	// Make "foo" live.
	mt.makeMutationsActive()

	// "foo" is being added.
	mt.writeIndexMutation("foo", sqlbase.DescriptorMutation{Direction: sqlbase.DescriptorMutation_ADD})
	if _, err := sqlDB.Exec(`CREATE INDEX foo ON t.test (c)`); !testutils.IsError(err, `duplicate index name: "foo"`) {
		t.Fatal(err)
	}
	// Make "foo" live.
	mt.makeMutationsActive()
	// Add column DROP mutation "b"
	mt.writeColumnMutation("b", sqlbase.DescriptorMutation{Direction: sqlbase.DescriptorMutation_DROP})
	if _, err := sqlDB.Exec(`CREATE INDEX bar ON t.test (b)`); !testutils.IsError(err, `index "bar" contains unknown column "b"`) {
		t.Fatal(err)
	}
	// Make "b" live.
	mt.makeMutationsActive()
	// "b" is being added.
	mt.writeColumnMutation("b", sqlbase.DescriptorMutation{Direction: sqlbase.DescriptorMutation_ADD})
	// An index referencing a column mutation that is being added
	// is allowed to be added.
	if _, err := sqlDB.Exec(`CREATE INDEX bar ON t.test (b)`); err != nil {
		t.Fatal(err)
	}
	// Make "b" live.
	mt.makeMutationsActive()

	// Test DROP INDEX in the presence of mutations.

	// Add index DROP mutation "foo""
	mt.writeIndexMutation("foo", sqlbase.DescriptorMutation{Direction: sqlbase.DescriptorMutation_DROP})
	// Noop.
	if _, err := sqlDB.Exec(`DROP INDEX [email protected]`); err != nil {
		t.Fatal(err)
	}
	// Make "foo" live.
	mt.makeMutationsActive()
	// "foo" is being added.
	mt.writeIndexMutation("foo", sqlbase.DescriptorMutation{Direction: sqlbase.DescriptorMutation_ADD})
	if _, err := sqlDB.Exec(`DROP INDEX [email protected]`); !testutils.IsError(err, `index "foo" in the middle of being added, try again later`) {
		t.Fatal(err)
	}
	// Make "foo" live.
	mt.makeMutationsActive()
	// Test ALTER TABLE ADD/DROP column in the presence of mutations.

	// Add column DROP mutation "b"
	mt.writeColumnMutation("b", sqlbase.DescriptorMutation{Direction: sqlbase.DescriptorMutation_DROP})
	if _, err := sqlDB.Exec(`ALTER TABLE t.test ADD b CHAR`); !testutils.IsError(err, `column "b" being dropped, try again later`) {
		t.Fatal(err)
	}
	// Noop.
	if _, err := sqlDB.Exec(`ALTER TABLE t.test DROP b`); err != nil {
		t.Fatal(err)
	}
	// Make "b" live.
	mt.makeMutationsActive()
	// "b" is being added.
	mt.writeColumnMutation("b", sqlbase.DescriptorMutation{Direction: sqlbase.DescriptorMutation_ADD})
	if _, err := sqlDB.Exec(`ALTER TABLE t.test ADD b CHAR`); !testutils.IsError(err, `duplicate column name: "b"`) {
//.........这里部分代码省略.........

// Test schema change purge failure doesn't leave DB in a bad state.
func TestSchemaChangePurgeFailure(t *testing.T) {
	defer leaktest.AfterTest(t)()

	params, _ := createTestServerParams()
	// Disable the async schema changer.
	var enableAsyncSchemaChanges uint32
	attempts := 0
	params.Knobs = base.TestingKnobs{
		SQLExecutor: &csql.ExecutorTestingKnobs{
			SchemaChangersStartBackfillNotification: func() error {
				attempts++
				// Return a deadline exceeded error during the second attempt
				// which attempts to clean up the schema change.
				if attempts == 2 {
					return errors.New("context deadline exceeded")
				}
				return nil
			},
		},
		SQLSchemaChangeManager: &csql.SchemaChangeManagerTestingKnobs{
			AsyncSchemaChangerExecNotification: func() error {
				if enable := atomic.LoadUint32(&enableAsyncSchemaChanges); enable == 0 {
					return errors.New("async schema changes are disabled")
				}
				return nil
			},
			// Speed up evaluation of async schema changes so that it
			// processes a purged schema change quickly.
			AsyncSchemaChangerExecQuickly: true,
		},
	}
	server, sqlDB, kvDB := serverutils.StartServer(t, params)
	defer server.Stopper().Stop()

	if _, err := sqlDB.Exec(`
CREATE DATABASE t;
CREATE TABLE t.test (k INT PRIMARY KEY, v INT);
`); err != nil {
		t.Fatal(err)
	}

	// Bulk insert.
	maxValue := csql.IndexBackfillChunkSize + 1
	insert := fmt.Sprintf(`INSERT INTO t.test VALUES (%d, %d)`, 0, maxValue)
	for i := 1; i <= maxValue; i++ {
		insert += fmt.Sprintf(` ,(%d, %d)`, i, maxValue-i)
	}
	if _, err := sqlDB.Exec(insert); err != nil {
		t.Fatal(err)
	}

	// Add a row with a duplicate value for v
	if _, err := sqlDB.Exec(
		`INSERT INTO t.test VALUES ($1, $2)`, maxValue+1, maxValue,
	); err != nil {
		t.Fatal(err)
	}

	// A schema change that violates integrity constraints.
	if _, err := sqlDB.Exec(
		"CREATE UNIQUE INDEX foo ON t.test (v)",
	); !testutils.IsError(err, "violates unique constraint") {
		t.Fatal(err)
	}
	// The deadline exceeded error in the schema change purge results in no
	// retry attempts of the purge.
	if e := 2; attempts != e {
		t.Fatalf("%d retries, despite allowing only (schema change + reverse) = %d", attempts, e)
	}

	// The index doesn't exist
	if _, err := sqlDB.Query(
		`SELECT v from [email protected]`,
	); !testutils.IsError(err, "index .* not found") {
		t.Fatal(err)
	}

	// Read table descriptor.
	tableDesc := sqlbase.GetTableDescriptor(kvDB, "t", "test")

	// There is still a mutation hanging off of it.
	if e := 1; len(tableDesc.Mutations) != e {
		t.Fatalf("the table has %d instead of %d mutations", len(tableDesc.Mutations), e)
	}
	// The mutation is for a DROP.
	if tableDesc.Mutations[0].Direction != sqlbase.DescriptorMutation_DROP {
		t.Fatalf("the table has mutation %v instead of a DROP", tableDesc.Mutations[0])
	}

	// There is still some garbage index data that needs to be purged. All the
	// rows from k = 0 to k = maxValue have index values. The k = maxValue + 1
	// row with the conflict doesn't contain an index value.
	numGarbageValues := csql.IndexBackfillChunkSize
	tablePrefix := roachpb.Key(keys.MakeTablePrefix(uint32(tableDesc.ID)))
	tableEnd := tablePrefix.PrefixEnd()
	if kvs, err := kvDB.Scan(tablePrefix, tableEnd, 0); err != nil {
		t.Fatal(err)
	} else if e := 1*(maxValue+2) + numGarbageValues; len(kvs) != e {
		t.Fatalf("expected %d key value pairs, but got %d", e, len(kvs))
//.........这里部分代码省略.........

// Test schema change backfills are not affected by various operations
// that run simultaneously.
func TestRaceWithBackfill(t *testing.T) {
	defer leaktest.AfterTest(t)()
	t.Skip("#7628")

	var backfillNotification chan bool
	params, _ := createTestServerParams()
	// Disable asynchronous schema change execution to allow synchronous path
	// to trigger start of backfill notification.
	params.Knobs = base.TestingKnobs{
		SQLExecutor: &csql.ExecutorTestingKnobs{
			SchemaChangersStartBackfillNotification: func() error {
				if backfillNotification != nil {
					// Close channel to notify that the backfill has started.
					close(backfillNotification)
				}
				return nil
			},
		},
		SQLSchemaChangeManager: &csql.SchemaChangeManagerTestingKnobs{
			AsyncSchemaChangerExecNotification: schemaChangeManagerDisabled,
		},
	}
	server, sqlDB, kvDB := serverutils.StartServer(t, params)
	defer server.Stopper().Stop()

	if _, err := sqlDB.Exec(`
CREATE DATABASE t;
CREATE TABLE t.test (k INT PRIMARY KEY, v INT, pi DECIMAL DEFAULT (DECIMAL '3.14'));
CREATE UNIQUE INDEX vidx ON t.test (v);
`); err != nil {
		t.Fatal(err)
	}

	// Bulk insert.
	maxValue := 4000
	insert := fmt.Sprintf(`INSERT INTO t.test VALUES (%d, %d)`, 0, maxValue)
	for i := 1; i <= maxValue; i++ {
		insert += fmt.Sprintf(` ,(%d, %d)`, i, maxValue-i)
	}
	if _, err := sqlDB.Exec(insert); err != nil {
		t.Fatal(err)
	}

	// Read table descriptor for version.
	tableDesc := sqlbase.GetTableDescriptor(kvDB, "t", "test")
	tablePrefix := roachpb.Key(keys.MakeTablePrefix(uint32(tableDesc.ID)))
	tableEnd := tablePrefix.PrefixEnd()
	// number of keys == 3 * number of rows; 2 column families and 1 index entry
	// for each row.
	if kvs, err := kvDB.Scan(tablePrefix, tableEnd, 0); err != nil {
		t.Fatal(err)
	} else if e := 3 * (maxValue + 1); len(kvs) != e {
		t.Fatalf("expected %d key value pairs, but got %d", e, len(kvs))
	}

	// Run some schema changes with operations.

	// Add column.
	backfillNotification = make(chan bool)
	runSchemaChangeWithOperations(
		t,
		sqlDB,
		kvDB,
		"ALTER TABLE t.test ADD COLUMN x DECIMAL DEFAULT (DECIMAL '1.4')",
		maxValue,
		4,
		backfillNotification)

	// Drop column.
	backfillNotification = make(chan bool)
	runSchemaChangeWithOperations(
		t,
		sqlDB,
		kvDB,
		"ALTER TABLE t.test DROP pi",
		maxValue,
		3,
		backfillNotification)

	// Add index.
	backfillNotification = make(chan bool)
	runSchemaChangeWithOperations(
		t,
		sqlDB,
		kvDB,
		"CREATE UNIQUE INDEX foo ON t.test (v)",
		maxValue,
		4,
		backfillNotification)

	// Drop index.
	backfillNotification = make(chan bool)
	runSchemaChangeWithOperations(
		t,
		sqlDB,
		kvDB,
		"DROP INDEX [email protected]",
		maxValue,
//.........这里部分代码省略.........

// Run a particular schema change and run some OLTP operations in parallel, as
// soon as the schema change starts executing its backfill.
func runSchemaChangeWithOperations(
	t *testing.T,
	sqlDB *gosql.DB,
	kvDB *client.DB,
	schemaChange string,
	maxValue int,
	keyMultiple int,
	backfillNotification chan bool,
) {
	tableDesc := sqlbase.GetTableDescriptor(kvDB, "t", "test")

	// Run the schema change in a separate goroutine.
	var wg sync.WaitGroup
	wg.Add(1)
	go func() {
		start := timeutil.Now()
		// Start schema change that eventually runs a backfill.
		if _, err := sqlDB.Exec(schemaChange); err != nil {
			t.Error(err)
		}
		t.Logf("schema change %s took %v", schemaChange, timeutil.Since(start))
		wg.Done()
	}()

	// Wait until the schema change backfill starts.
	<-backfillNotification

	// Run a variety of operations during the backfill.

	// Grabbing a schema change lease on the table will fail, disallowing
	// another schema change from being simultaneously executed.
	sc := csql.NewSchemaChangerForTesting(tableDesc.ID, 0, 0, *kvDB, nil)
	if l, err := sc.AcquireLease(); err == nil {
		t.Fatalf("schema change lease acquisition on table %d succeeded: %v", tableDesc.ID, l)
	}

	// Update some rows.
	var updatedKeys []int
	for i := 0; i < 10; i++ {
		k := rand.Intn(maxValue)
		v := maxValue + i + 1
		if _, err := sqlDB.Exec(`UPDATE t.test SET v = $2 WHERE k = $1`, k, v); err != nil {
			t.Fatal(err)
		}
		updatedKeys = append(updatedKeys, k)
	}

	// Reupdate updated values back to what they were before.
	for _, k := range updatedKeys {
		if _, err := sqlDB.Exec(`UPDATE t.test SET v = $2 WHERE k = $1`, k, maxValue-k); err != nil {
			t.Fatal(err)
		}
	}

	// Delete some rows.
	deleteStartKey := rand.Intn(maxValue - 10)
	for i := 0; i < 10; i++ {
		if _, err := sqlDB.Exec(`DELETE FROM t.test WHERE k = $1`, deleteStartKey+i); err != nil {
			t.Fatal(err)
		}
	}
	// Reinsert deleted rows.
	for i := 0; i < 10; i++ {
		k := deleteStartKey + i
		if _, err := sqlDB.Exec(`INSERT INTO t.test VALUES($1, $2)`, k, maxValue-k); err != nil {
			t.Fatal(err)
		}
	}

	// Insert some new rows.
	numInserts := 10
	for i := 0; i < numInserts; i++ {
		if _, err := sqlDB.Exec(`INSERT INTO t.test VALUES($1, $2)`, maxValue+i+1, maxValue+i+1); err != nil {
			t.Fatal(err)
		}
	}

	wg.Wait() // for schema change to complete.

	// Verify the number of keys left behind in the table to validate schema
	// change operations.
	tablePrefix := roachpb.Key(keys.MakeTablePrefix(uint32(tableDesc.ID)))
	tableEnd := tablePrefix.PrefixEnd()
	if kvs, err := kvDB.Scan(tablePrefix, tableEnd, 0); err != nil {
		t.Fatal(err)
	} else if e := keyMultiple * (maxValue + numInserts + 1); len(kvs) != e {
		t.Fatalf("expected %d key value pairs, but got %d", e, len(kvs))
	}

	// Delete the rows inserted.
	for i := 0; i < numInserts; i++ {
		if _, err := sqlDB.Exec(`DELETE FROM t.test WHERE k = $1`, maxValue+i+1); err != nil {
			t.Fatal(err)
		}
	}
}

func TestAsyncSchemaChanger(t *testing.T) {
	defer leaktest.AfterTest(t)()
	// The descriptor changes made must have an immediate effect
	// so disable leases on tables.
	defer csql.TestDisableTableLeases()()
	// Disable synchronous schema change execution so the asynchronous schema
	// changer executes all schema changes.
	params, _ := createTestServerParams()
	params.Knobs = base.TestingKnobs{
		SQLExecutor: &csql.ExecutorTestingKnobs{
			SyncSchemaChangersFilter: func(tscc csql.TestingSchemaChangerCollection) {
				tscc.ClearSchemaChangers()
			},
		},
		SQLSchemaChangeManager: &csql.SchemaChangeManagerTestingKnobs{
			AsyncSchemaChangerExecQuickly: true,
		},
	}
	s, sqlDB, kvDB := serverutils.StartServer(t, params)
	defer s.Stopper().Stop()

	if _, err := sqlDB.Exec(`
CREATE DATABASE t;
CREATE TABLE t.test (k CHAR PRIMARY KEY, v CHAR);
INSERT INTO t.test VALUES ('a', 'b'), ('c', 'd');
`); err != nil {
		t.Fatal(err)
	}

	// Read table descriptor for version.
	tableDesc := sqlbase.GetTableDescriptor(kvDB, "t", "test")

	// A long running schema change operation runs through
	// a state machine that increments the version by 3.
	expectedVersion := tableDesc.Version + 3

	// Run some schema change
	if _, err := sqlDB.Exec(`
CREATE INDEX foo ON t.test (v)
`); err != nil {
		t.Fatal(err)
	}

	retryOpts := retry.Options{
		InitialBackoff: 20 * time.Millisecond,
		MaxBackoff:     200 * time.Millisecond,
		Multiplier:     2,
	}

	// Wait until index is created.
	for r := retry.Start(retryOpts); r.Next(); {
		tableDesc = sqlbase.GetTableDescriptor(kvDB, "t", "test")
		if len(tableDesc.Indexes) == 1 {
			break
		}
	}

	// Ensure that the indexes have been created.
	mTest := mutationTest{
		T:         t,
		kvDB:      kvDB,
		sqlDB:     sqlDB,
		tableDesc: tableDesc,
	}
	indexQuery := `SELECT v FROM [email protected]`
	_ = mTest.checkQueryResponse(indexQuery, [][]string{{"b"}, {"d"}})

	// Ensure that the version has been incremented.
	tableDesc = sqlbase.GetTableDescriptor(kvDB, "t", "test")
	newVersion := tableDesc.Version
	if newVersion != expectedVersion {
		t.Fatalf("bad version; e = %d, v = %d", expectedVersion, newVersion)
	}

	// Apply a schema change that only sets the UpVersion bit.
	expectedVersion = newVersion + 1

	if _, err := sqlDB.Exec(`
ALTER INDEX [email protected] RENAME TO ufo
`); err != nil {
		t.Fatal(err)
	}

	for r := retry.Start(retryOpts); r.Next(); {
		// Ensure that the version gets incremented.
		tableDesc = sqlbase.GetTableDescriptor(kvDB, "t", "test")
		name := tableDesc.I