Golang Batch.CPut方法代碼示例

// writeDescriptor takes a Table or Database descriptor and writes it
// if needed, incrementing the descriptor counter.
func (p *planner) writeDescriptor(plainKey descriptorKey, descriptor descriptorProto, ifNotExists bool) error {
	key := plainKey.Key()
	// Check whether key exists.
	gr, err := p.txn.Get(key)
	if err != nil {
		return err
	}

	if gr.Exists() {
		if ifNotExists {
			// Noop.
			return nil
		}
		// Key exists, but we don't want it to: error out.
		return fmt.Errorf("%s %q already exists", descriptor.TypeName(), plainKey.Name())
	}

	// Increment unique descriptor counter.
	if ir, err := p.txn.Inc(keys.DescIDGenerator, 1); err == nil {
		descriptor.SetID(structured.ID(ir.ValueInt() - 1))
	} else {
		return err
	}

	// TODO(pmattis): The error currently returned below is likely going to be
	// difficult to interpret.
	// TODO(pmattis): Need to handle if-not-exists here as well.
	descKey := structured.MakeDescMetadataKey(descriptor.GetID())
	b := client.Batch{}
	b.CPut(key, descKey, nil)
	b.CPut(descKey, descriptor, nil)
	return p.txn.Run(&b)
}

// RenameDatabase renames the database.
// Privileges: security.RootUser user.
//   Notes: postgres requires superuser, db owner, or "CREATEDB".
//          mysql >= 5.1.23 does not allow database renames.
func (p *planner) RenameDatabase(n *parser.RenameDatabase) (planNode, error) {
	if n.Name == "" || n.NewName == "" {
		return nil, errEmptyDatabaseName
	}

	if p.session.User != security.RootUser {
		return nil, fmt.Errorf("only %s is allowed to rename databases", security.RootUser)
	}

	dbDesc, err := p.getDatabaseDesc(string(n.Name))
	if err != nil {
		return nil, err
	}
	if dbDesc == nil {
		return nil, databaseDoesNotExistError(string(n.Name))
	}

	if n.Name == n.NewName {
		// Noop.
		return &emptyNode{}, nil
	}

	// Now update the nameMetadataKey and the descriptor.
	descKey := sqlbase.MakeDescMetadataKey(dbDesc.GetID())
	dbDesc.SetName(string(n.NewName))

	if err := dbDesc.Validate(); err != nil {
		return nil, err
	}

	newKey := databaseKey{string(n.NewName)}.Key()
	oldKey := databaseKey{string(n.Name)}.Key()
	descID := dbDesc.GetID()
	descDesc := sqlbase.WrapDescriptor(dbDesc)

	b := client.Batch{}
	b.CPut(newKey, descID, nil)
	b.Put(descKey, descDesc)
	b.Del(oldKey)

	if err := p.txn.Run(&b); err != nil {
		if _, ok := err.(*roachpb.ConditionFailedError); ok {
			return nil, fmt.Errorf("the new database name %q already exists", string(n.NewName))
		}
		return nil, err
	}

	p.setTestingVerifyMetadata(func(systemConfig config.SystemConfig) error {
		if err := expectDescriptorID(systemConfig, newKey, descID); err != nil {
			return err
		}
		if err := expectDescriptor(systemConfig, descKey, descDesc); err != nil {
			return err
		}
		return expectDeleted(systemConfig, oldKey)
	})

	return &emptyNode{}, nil
}

func (p *planner) makeBackfillBatch(tableName *parser.QualifiedName, tableDesc *TableDescriptor, indexDescs ...IndexDescriptor) (client.Batch, error) {
	b := client.Batch{}
	// Get all the rows affected.
	// TODO(vivek): Avoid going through Select.
	// TODO(tamird): Support partial indexes?
	row, err := p.Select(&parser.Select{
		Exprs: parser.SelectExprs{parser.StarSelectExpr()},
		From:  parser.TableExprs{&parser.AliasedTableExpr{Expr: tableName}},
	})
	if err != nil {
		return b, err
	}

	// Construct a map from column ID to the index the value appears at within a
	// row.
	colIDtoRowIndex := map[ColumnID]int{}
	for i, name := range row.Columns() {
		c, err := tableDesc.FindColumnByName(name)
		if err != nil {
			return b, err
		}
		colIDtoRowIndex[c.ID] = i
	}

	// TODO(tamird): This will fall down in production use. We need to do
	// something better (see #2036). In particular, this implementation
	// has the following problems:
	// - Very large tables will generate an enormous batch here. This
	// isn't really a problem in itself except that it will exacerbate
	// the other issue:
	// - Any non-quiescent table that this runs against will end up with
	// an inconsistent index. This is because as inserts/updates continue
	// to roll in behind this operation's read front, the written index
	// will become incomplete/stale before it's written.

	for row.Next() {
		rowVals := row.Values()

		for _, indexDesc := range indexDescs {
			secondaryIndexEntries, err := encodeSecondaryIndexes(
				tableDesc.ID, []IndexDescriptor{indexDesc}, colIDtoRowIndex, rowVals)
			if err != nil {
				return b, err
			}

			for _, secondaryIndexEntry := range secondaryIndexEntries {
				if log.V(2) {
					log.Infof("CPut %s -> %v", prettyKey(secondaryIndexEntry.key, 0),
						secondaryIndexEntry.value)
				}
				b.CPut(secondaryIndexEntry.key, secondaryIndexEntry.value, nil)
			}
		}
	}

	return b, row.Err()
}

// createDescriptor implements the DescriptorAccessor interface.
func (p *planner) createDescriptor(plainKey sqlbase.DescriptorKey, descriptor sqlbase.DescriptorProto, ifNotExists bool) (bool, error) {
	idKey := plainKey.Key()
	// Check whether idKey exists.
	gr, err := p.txn.Get(idKey)
	if err != nil {
		return false, err
	}

	if gr.Exists() {
		if ifNotExists {
			// Noop.
			return false, nil
		}
		// Key exists, but we don't want it to: error out.
		return false, fmt.Errorf("%s %q already exists", descriptor.TypeName(), plainKey.Name())
	}

	// Increment unique descriptor counter.
	if ir, err := p.txn.Inc(keys.DescIDGenerator, 1); err == nil {
		descriptor.SetID(sqlbase.ID(ir.ValueInt() - 1))
	} else {
		return false, err
	}

	// TODO(pmattis): The error currently returned below is likely going to be
	// difficult to interpret.
	//
	// TODO(pmattis): Need to handle if-not-exists here as well.
	//
	// TODO(pmattis): This is writing the namespace and descriptor table entries,
	// but not going through the normal INSERT logic and not performing a precise
	// mimicry. In particular, we're only writing a single key per table, while
	// perfect mimicry would involve writing a sentinel key for each row as well.
	descKey := sqlbase.MakeDescMetadataKey(descriptor.GetID())

	b := client.Batch{}
	descID := descriptor.GetID()
	descDesc := sqlbase.WrapDescriptor(descriptor)
	if log.V(2) {
		log.Infof("CPut %s -> %d", idKey, descID)
		log.Infof("CPut %s -> %s", descKey, descDesc)
	}
	b.CPut(idKey, descID, nil)
	b.CPut(descKey, descDesc, nil)

	p.setTestingVerifyMetadata(func(systemConfig config.SystemConfig) error {
		if err := expectDescriptorID(systemConfig, idKey, descID); err != nil {
			return err
		}
		return expectDescriptor(systemConfig, descKey, descDesc)
	})

	return true, p.txn.Run(&b)
}

// updateRangeDescriptor adds a ConditionalPut on the range descriptor. The
// conditional put verifies that changes to the range descriptor are made in a
// well-defined order, preventing a scenario where a wayward replica which is
// no longer part of the original Raft group comes back online to form a
// splinter group with a node which was also a former replica, and hijacks the
// range descriptor. This is a last line of defense; other mechanisms should
// prevent rogue replicas from getting this far (see #768).
func updateRangeDescriptor(b *client.Batch, descKey proto.Key, oldDesc, newDesc *proto.RangeDescriptor) error {
	var oldValue []byte
	if oldDesc != nil {
		var err error
		if oldValue, err = gogoproto.Marshal(oldDesc); err != nil {
			return err
		}
	}
	newValue, err := gogoproto.Marshal(newDesc)
	if err != nil {
		return err
	}
	b.CPut(descKey, newValue, oldValue)
	return nil
}

// RenameDatabase renames the database.
// Privileges: "root" user.
//   Notes: postgres requires superuser, db owner, or "CREATEDB".
//          mysql >= 5.1.23 does not allow database renames.
func (p *planner) RenameDatabase(n *parser.RenameDatabase) (planNode, error) {
	if n.Name == "" || n.NewName == "" {
		return nil, errEmptyDatabaseName
	}

	if p.user != security.RootUser {
		return nil, fmt.Errorf("only %s is allowed to rename databases", security.RootUser)
	}

	dbDesc, err := p.getDatabaseDesc(string(n.Name))
	if err != nil {
		return nil, err
	}

	if n.Name == n.NewName {
		// Noop.
		return &valuesNode{}, nil
	}

	// Now update the nameMetadataKey and the descriptor.
	descKey := MakeDescMetadataKey(dbDesc.GetID())
	dbDesc.SetName(string(n.NewName))

	if err := dbDesc.Validate(); err != nil {
		return nil, err
	}

	b := client.Batch{}
	b.CPut(databaseKey{string(n.NewName)}.Key(), dbDesc.GetID(), nil)
	b.Put(descKey, dbDesc)
	b.Del(databaseKey{string(n.Name)}.Key())

	// Mark transaction as operating on the system DB.
	p.txn.SetSystemDBTrigger()
	if err := p.txn.Run(&b); err != nil {
		if _, ok := err.(*proto.ConditionFailedError); ok {
			return nil, fmt.Errorf("the new database name %q already exists", string(n.NewName))
		}
		return nil, err
	}

	return &valuesNode{}, nil
}

// createDescriptor takes a Table or Database descriptor and creates it
// if needed, incrementing the descriptor counter.
func (p *planner) createDescriptor(plainKey descriptorKey, descriptor descriptorProto, ifNotExists bool) error {
	key := plainKey.Key()
	// Check whether key exists.
	gr, err := p.txn.Get(key)
	if err != nil {
		return err
	}

	if gr.Exists() {
		if ifNotExists {
			// Noop.
			return nil
		}
		// Key exists, but we don't want it to: error out.
		return fmt.Errorf("%s %q already exists", descriptor.TypeName(), plainKey.Name())
	}

	// Increment unique descriptor counter.
	if ir, err := p.txn.Inc(keys.DescIDGenerator, 1); err == nil {
		descriptor.SetID(ID(ir.ValueInt() - 1))
	} else {
		return err
	}

	// TODO(pmattis): The error currently returned below is likely going to be
	// difficult to interpret.
	//
	// TODO(pmattis): Need to handle if-not-exists here as well.
	//
	// TODO(pmattis): This is writing the namespace and descriptor table entries,
	// but not going through the normal INSERT logic and not performing a precise
	// mimicry. In particular, we're only writing a single key per table, while
	// perfect mimicry would involve writing a sentinel key for each row as well.
	descKey := MakeDescMetadataKey(descriptor.GetID())

	b := client.Batch{}
	b.CPut(key, descriptor.GetID(), nil)
	b.CPut(descKey, wrapDescriptor(descriptor), nil)

	return p.txn.Run(&b)
}

//.........這裏部分代碼省略.........
	// Secondary indexes needing updating.
	var indexes []IndexDescriptor
	for _, index := range tableDesc.Indexes {
		for _, id := range index.ColumnIDs {
			if _, ok := colIDSet[id]; ok {
				indexes = append(indexes, index)
				break
			}
		}
	}

	// Update all the rows.
	var b client.Batch
	for rows.Next() {
		rowVals := rows.Values()
		primaryIndexKey, _, err := encodeIndexKey(
			primaryIndex.ColumnIDs, colIDtoRowIndex, rowVals, primaryIndexKeyPrefix)
		if err != nil {
			return nil, err
		}
		// Compute the current secondary index key:value pairs for this row.
		secondaryIndexEntries, err := encodeSecondaryIndexes(
			tableDesc.ID, indexes, colIDtoRowIndex, rowVals)
		if err != nil {
			return nil, err
		}

		// Our updated value expressions occur immediately after the plain
		// columns in the output.
		newVals := rowVals[len(tableDesc.Columns):]
		// Update the row values.
		for i, col := range cols {
			val := newVals[i]
			if !col.Nullable && val == parser.DNull {
				return nil, fmt.Errorf("null value in column %q violates not-null constraint", col.Name)
			}
			rowVals[colIDtoRowIndex[col.ID]] = val
		}
		// Compute the new secondary index key:value pairs for this row.
		newSecondaryIndexEntries, err := encodeSecondaryIndexes(
			tableDesc.ID, indexes, colIDtoRowIndex, rowVals)
		if err != nil {
			return nil, err
		}
		// Update secondary indexes.
		for i, newSecondaryIndexEntry := range newSecondaryIndexEntries {
			secondaryIndexEntry := secondaryIndexEntries[i]
			if !bytes.Equal(newSecondaryIndexEntry.key, secondaryIndexEntry.key) {
				if log.V(2) {
					log.Infof("CPut %q -> %v", newSecondaryIndexEntry.key, newSecondaryIndexEntry.value)
				}
				b.CPut(newSecondaryIndexEntry.key, newSecondaryIndexEntry.value, nil)
				if log.V(2) {
					log.Infof("Del %q", secondaryIndexEntry.key)
				}
				b.Del(secondaryIndexEntry.key)
			}
		}

		// Add the new values.
		for i, val := range newVals {
			col := cols[i]

			primitive, err := convertDatum(col, val)
			if err != nil {
				return nil, err
			}

			key := MakeColumnKey(col.ID, primaryIndexKey)
			if primitive != nil {
				// We only output non-NULL values. Non-existent column keys are
				// considered NULL during scanning and the row sentinel ensures we know
				// the row exists.
				if log.V(2) {
					log.Infof("Put %q -> %v", key, val)
				}

				b.Put(key, primitive)
			} else {
				// The column might have already existed but is being set to NULL, so
				// delete it.
				if log.V(2) {
					log.Infof("Del %q", key)
				}

				b.Del(key)
			}
		}
	}

	if err := rows.Err(); err != nil {
		return nil, err
	}
	if err := p.txn.Run(&b); err != nil {
		return nil, convertBatchError(tableDesc, b, err)
	}

	// TODO(tamird/pmattis): return the number of affected rows.
	return &valuesNode{}, nil
}

// updateRow adds to the batch the kv operations necessary to update a table row
// with the given values.
//
// The row corresponding to oldValues is updated with the ones in updateValues.
// Note that updateValues only contains the ones that are changing.
//
// The return value is only good until the next call to UpdateRow.
func (ru *rowUpdater) updateRow(
	b *client.Batch,
	oldValues []parser.Datum,
	updateValues []parser.Datum,
) ([]parser.Datum, error) {
	if len(oldValues) != len(ru.fetchCols) {
		return nil, util.Errorf("got %d values but expected %d", len(oldValues), len(ru.fetchCols))
	}
	if len(updateValues) != len(ru.updateCols) {
		return nil, util.Errorf("got %d values but expected %d", len(updateValues), len(ru.updateCols))
	}

	primaryIndexKey, secondaryIndexEntries, err := ru.helper.encodeIndexes(ru.fetchColIDtoRowIndex, oldValues)
	if err != nil {
		return nil, err
	}

	// Check that the new value types match the column types. This needs to
	// happen before index encoding because certain datum types (i.e. tuple)
	// cannot be used as index values.
	for i, val := range updateValues {
		if ru.marshalled[i], err = sqlbase.MarshalColumnValue(ru.updateCols[i], val); err != nil {
			return nil, err
		}
	}

	// Update the row values.
	copy(ru.newValues, oldValues)
	for i, updateCol := range ru.updateCols {
		ru.newValues[ru.fetchColIDtoRowIndex[updateCol.ID]] = updateValues[i]
	}

	newPrimaryIndexKey := primaryIndexKey
	rowPrimaryKeyChanged := false
	var newSecondaryIndexEntries []sqlbase.IndexEntry
	if ru.primaryKeyColChange {
		newPrimaryIndexKey, newSecondaryIndexEntries, err = ru.helper.encodeIndexes(ru.fetchColIDtoRowIndex, ru.newValues)
		if err != nil {
			return nil, err
		}
		rowPrimaryKeyChanged = !bytes.Equal(primaryIndexKey, newPrimaryIndexKey)
	} else {
		newSecondaryIndexEntries, err = sqlbase.EncodeSecondaryIndexes(
			ru.helper.tableDesc.ID, ru.helper.indexes, ru.fetchColIDtoRowIndex, ru.newValues)
		if err != nil {
			return nil, err
		}
	}

	if rowPrimaryKeyChanged {
		err := ru.rd.deleteRow(b, oldValues)
		if err != nil {
			return nil, err
		}
		err = ru.ri.insertRow(b, ru.newValues)
		return ru.newValues, err
	}

	// Update secondary indexes.
	for i, newSecondaryIndexEntry := range newSecondaryIndexEntries {
		secondaryIndexEntry := secondaryIndexEntries[i]
		secondaryKeyChanged := !bytes.Equal(newSecondaryIndexEntry.Key, secondaryIndexEntry.Key)
		if secondaryKeyChanged {
			if log.V(2) {
				log.Infof("Del %s", secondaryIndexEntry.Key)
			}
			b.Del(secondaryIndexEntry.Key)
			// Do not update Indexes in the DELETE_ONLY state.
			if _, ok := ru.deleteOnlyIndex[i]; !ok {
				if log.V(2) {
					log.Infof("CPut %s -> %v", newSecondaryIndexEntry.Key, newSecondaryIndexEntry.Value)
				}
				b.CPut(newSecondaryIndexEntry.Key, newSecondaryIndexEntry.Value, nil)
			}
		}
	}

	// Add the new values.
	for i, val := range updateValues {
		col := ru.updateCols[i]

		if ru.helper.columnInPK(col.ID) {
			// Skip primary key columns as their values are encoded in the row
			// sentinel key which is guaranteed to exist for as long as the row
			// exists.
			continue
		}

		ru.key = keys.MakeColumnKey(newPrimaryIndexKey, uint32(col.ID))
		if ru.marshalled[i].RawBytes != nil {
			// We only output non-NULL values. Non-existent column keys are
			// considered NULL during scanning and the row sentinel ensures we know
			// the row exists.
//.........這裏部分代碼省略.........

// insertRow adds to the batch the kv operations necessary to insert a table row
// with the given values.
func (ri *rowInserter) insertRow(b *client.Batch, values []parser.Datum) error {
	if len(values) != len(ri.insertCols) {
		return util.Errorf("got %d values but expected %d", len(values), len(ri.insertCols))
	}

	// Encode the values to the expected column type. This needs to
	// happen before index encoding because certain datum types (i.e. tuple)
	// cannot be used as index values.
	for i, val := range values {
		// Make sure the value can be written to the column before proceeding.
		var err error
		if ri.marshalled[i], err = sqlbase.MarshalColumnValue(ri.insertCols[i], val); err != nil {
			return err
		}
	}

	primaryIndexKey, secondaryIndexEntries, err := ri.helper.encodeIndexes(ri.insertColIDtoRowIndex, values)
	if err != nil {
		return err
	}

	// Write the row sentinel. We want to write the sentinel first in case
	// we are trying to insert a duplicate primary key: if we write the
	// secondary indexes first, we may get an error that looks like a
	// uniqueness violation on a non-unique index.
	ri.key = keys.MakeNonColumnKey(primaryIndexKey)
	if log.V(2) {
		log.Infof("CPut %s -> NULL", ri.key)
	}
	// Each sentinel value needs a distinct RawBytes field as the computed
	// checksum includes the key the value is associated with.
	ri.sentinelValue.SetBytes([]byte{})
	b.CPut(&ri.key, &ri.sentinelValue, nil)
	ri.key = nil

	for _, secondaryIndexEntry := range secondaryIndexEntries {
		if log.V(2) {
			log.Infof("CPut %s -> %v", secondaryIndexEntry.Key, secondaryIndexEntry.Value)
		}
		ri.key = secondaryIndexEntry.Key
		b.CPut(&ri.key, secondaryIndexEntry.Value, nil)
	}
	ri.key = nil

	// Write the row columns.
	for i, val := range values {
		col := ri.insertCols[i]

		if ri.helper.columnInPK(col.ID) {
			// Skip primary key columns as their values are encoded in the row
			// sentinel key which is guaranteed to exist for as long as the row
			// exists.
			continue
		}

		if ri.marshalled[i].RawBytes != nil {
			// We only output non-NULL values. Non-existent column keys are
			// considered NULL during scanning and the row sentinel ensures we know
			// the row exists.

			ri.key = keys.MakeColumnKey(primaryIndexKey, uint32(col.ID))
			if log.V(2) {
				log.Infof("CPut %s -> %v", ri.key, val)
			}

			b.CPut(&ri.key, &ri.marshalled[i], nil)
			ri.key = nil
		}
	}

	return nil
}

//.........這裏部分代碼省略.........
	// will fail on big tables (see #3274).

	// Delete the entire dropped columns.
	// This used to use SQL UPDATE in the past to update the dropped
	// column to NULL; but a column in the process of being
	// dropped is placed in the table descriptor mutations, and
	// a SQL UPDATE of a column in mutations will fail.
	if len(droppedColumnDescs) > 0 {
		// Run a scan across the table using the primary key.
		start := roachpb.Key(MakeIndexKeyPrefix(oldTableDesc.ID, oldTableDesc.PrimaryIndex.ID))
		// Use a different batch to perform the scan.
		batch := &client.Batch{}
		batch.Scan(start, start.PrefixEnd(), 0)
		if pErr := p.txn.Run(batch); pErr != nil {
			return pErr
		}
		for _, result := range batch.Results {
			var sentinelKey roachpb.Key
			for _, kv := range result.Rows {
				if sentinelKey == nil || !bytes.HasPrefix(kv.Key, sentinelKey) {
					// Sentinel keys have a 0 suffix indicating 0 bytes of column
					// ID. Strip off that suffix to determine the prefix shared with the
					// other keys for the row.
					sentinelKey = stripColumnIDLength(kv.Key)
					for _, columnDesc := range droppedColumnDescs {
						// Delete the dropped column.
						colKey := keys.MakeColumnKey(sentinelKey, uint32(columnDesc.ID))
						if log.V(2) {
							log.Infof("Del %s", colKey)
						}
						b.Del(colKey)
					}
				}
			}
		}
	}

	for _, indexDescriptor := range droppedIndexDescs {
		indexPrefix := MakeIndexKeyPrefix(oldTableDesc.ID, indexDescriptor.ID)

		// Delete the index.
		indexStartKey := roachpb.Key(indexPrefix)
		indexEndKey := indexStartKey.PrefixEnd()
		if log.V(2) {
			log.Infof("DelRange %s - %s", indexStartKey, indexEndKey)
		}
		b.DelRange(indexStartKey, indexEndKey)
	}

	if len(newIndexDescs) > 0 {
		// Get all the rows affected.
		// TODO(vivek): Avoid going through Select.
		// TODO(tamird): Support partial indexes?
		// Use a scanNode with SELECT to pass in a TableDescriptor
		// to the SELECT without needing to use a parser.QualifiedName,
		// because we want to run schema changes from a gossip feed of
		// table IDs.
		scan := &scanNode{
			planner: p,
			txn:     p.txn,
			desc:    oldTableDesc,
		}
		scan.initDescDefaults()
		rows, pErr := p.selectIndex(&selectNode{}, scan, nil, false)
		if pErr != nil {
			return pErr
		}

		// Construct a map from column ID to the index the value appears at within a
		// row.
		colIDtoRowIndex, pErr := makeColIDtoRowIndex(rows, oldTableDesc)
		if pErr != nil {
			return pErr
		}

		for rows.Next() {
			rowVals := rows.Values()

			for _, newIndexDesc := range newIndexDescs {
				secondaryIndexEntries, pErr := encodeSecondaryIndexes(
					oldTableDesc.ID, []IndexDescriptor{newIndexDesc}, colIDtoRowIndex, rowVals)
				if pErr != nil {
					return pErr
				}

				for _, secondaryIndexEntry := range secondaryIndexEntries {
					if log.V(2) {
						log.Infof("CPut %s -> %v", secondaryIndexEntry.key,
							secondaryIndexEntry.value)
					}
					b.CPut(secondaryIndexEntry.key, secondaryIndexEntry.value, nil)
				}
			}
		}

		return rows.PErr()
	}

	return nil
}

//.........這裏部分代碼省略.........
		batch := &client.Batch{}
		batch.Scan(start, start.PrefixEnd(), 0)
		if err := p.txn.Run(batch); err != nil {
			return err
		}
		for _, result := range batch.Results {
			var sentinelKey roachpb.Key
			for _, kv := range result.Rows {
				if sentinelKey == nil || !bytes.HasPrefix(kv.Key, sentinelKey) {
					// Sentinel keys have a 0 suffix indicating 0 bytes of column
					// ID. Strip off that suffix to determine the prefix shared with the
					// other keys for the row.
					sentinelKey = stripColumnIDLength(kv.Key)
					for _, columnDesc := range droppedColumnDescs {
						// Delete the dropped column.
						colKey := keys.MakeColumnKey(sentinelKey, uint32(columnDesc.ID))
						if log.V(2) {
							log.Infof("Del %s", colKey)
						}
						b.Del(colKey)
					}
				}
			}
		}
	}

	for _, indexDescriptor := range droppedIndexDescs {
		indexPrefix := MakeIndexKeyPrefix(newTableDesc.ID, indexDescriptor.ID)

		// Delete the index.
		indexStartKey := roachpb.Key(indexPrefix)
		indexEndKey := indexStartKey.PrefixEnd()
		if log.V(2) {
			log.Infof("DelRange %s - %s", indexStartKey, indexEndKey)
		}
		b.DelRange(indexStartKey, indexEndKey)
	}

	if len(newIndexDescs) > 0 {
		// Get all the rows affected.
		// TODO(vivek): Avoid going through Select.
		// TODO(tamird): Support partial indexes?
		// Use a scanNode with SELECT to pass in a TableDescriptor
		// to the SELECT without needing to use a parser.QualifiedName,
		// because we want to run schema changes from a gossip feed of
		// table IDs.
		scan := &scanNode{
			planner: p,
			txn:     p.txn,
			desc:    oldTableDesc,
		}
		scan.initDescDefaults()
		rows, err := p.selectWithScan(scan, &parser.Select{Exprs: oldTableDesc.allColumnsSelector()})
		if err != nil {
			return err
		}

		// Construct a map from column ID to the index the value appears at within a
		// row.
		colIDtoRowIndex, err := makeColIDtoRowIndex(rows, oldTableDesc)
		if err != nil {
			return err
		}

		// TODO(tamird): This will fall down in production use. We need to do
		// something better (see #2036). In particular, this implementation
		// has the following problems:
		// - Very large tables will generate an enormous batch here. This
		// isn't really a problem in itself except that it will exacerbate
		// the other issue:
		// - Any non-quiescent table that this runs against will end up with
		// an inconsistent index. This is because as inserts/updates continue
		// to roll in behind this operation's read front, the written index
		// will become incomplete/stale before it's written.

		for rows.Next() {
			rowVals := rows.Values()

			for _, newIndexDesc := range newIndexDescs {
				secondaryIndexEntries, err := encodeSecondaryIndexes(
					oldTableDesc.ID, []IndexDescriptor{newIndexDesc}, colIDtoRowIndex, rowVals)
				if err != nil {
					return err
				}

				for _, secondaryIndexEntry := range secondaryIndexEntries {
					if log.V(2) {
						log.Infof("CPut %s -> %v", secondaryIndexEntry.key,
							secondaryIndexEntry.value)
					}
					b.CPut(secondaryIndexEntry.key, secondaryIndexEntry.value, nil)
				}
			}
		}

		return rows.Err()
	}

	return nil
}

// Insert inserts rows into the database.
// Privileges: INSERT on table
//   Notes: postgres requires INSERT. No "on duplicate key update" option.
//          mysql requires INSERT. Also requires UPDATE on "ON DUPLICATE KEY UPDATE".
func (p *planner) Insert(n *parser.Insert) (planNode, error) {
	tableDesc, err := p.getTableDesc(n.Table)
	if err != nil {
		return nil, err
	}

	if err := p.checkPrivilege(tableDesc, privilege.INSERT); err != nil {
		return nil, err
	}

	// Determine which columns we're inserting into.
	cols, err := p.processColumns(tableDesc, n.Columns)
	if err != nil {
		return nil, err
	}

	// Construct a map from column ID to the index the value appears at within a
	// row.
	colIDtoRowIndex := map[ColumnID]int{}
	for i, c := range cols {
		colIDtoRowIndex[c.ID] = i
	}

	// Verify we have at least the columns that are part of the primary key.
	primaryKeyCols := map[ColumnID]struct{}{}
	for i, id := range tableDesc.PrimaryIndex.ColumnIDs {
		if _, ok := colIDtoRowIndex[id]; !ok {
			return nil, fmt.Errorf("missing %q primary key column", tableDesc.PrimaryIndex.ColumnNames[i])
		}
		primaryKeyCols[id] = struct{}{}
	}

	// Transform the values into a rows object. This expands SELECT statements or
	// generates rows from the values contained within the query.
	rows, err := p.makePlan(n.Rows)
	if err != nil {
		return nil, err
	}

	primaryIndex := tableDesc.PrimaryIndex
	primaryIndexKeyPrefix := MakeIndexKeyPrefix(tableDesc.ID, primaryIndex.ID)

	b := client.Batch{}

	for rows.Next() {
		values := rows.Values()
		for range cols[len(values):] {
			values = append(values, parser.DNull)
		}

		for _, col := range tableDesc.Columns {
			if !col.Nullable {
				if i, ok := colIDtoRowIndex[col.ID]; !ok || values[i] == parser.DNull {
					return nil, fmt.Errorf("null value in column %q violates not-null constraint", col.Name)
				}
			}
		}

		primaryIndexKey, _, err := encodeIndexKey(
			primaryIndex.ColumnIDs, colIDtoRowIndex, values, primaryIndexKeyPrefix)
		if err != nil {
			return nil, err
		}

		// Write the secondary indexes.
		secondaryIndexEntries, err := encodeSecondaryIndexes(
			tableDesc.ID, tableDesc.Indexes, colIDtoRowIndex, values)
		if err != nil {
			return nil, err
		}

		for _, secondaryIndexEntry := range secondaryIndexEntries {
			if log.V(2) {
				log.Infof("CPut %q -> %v", secondaryIndexEntry.key, secondaryIndexEntry.value)
			}
			b.CPut(secondaryIndexEntry.key, secondaryIndexEntry.value, nil)
		}

		// Write the row sentinel.
		if log.V(2) {
			log.Infof("CPut %q -> NULL", primaryIndexKey)
		}
		b.CPut(primaryIndexKey, nil, nil)

		// Write the row columns.
		for i, val := range values {
			col := cols[i]

			// Make sure the value can be written to the column before proceeding.
			primitive, err := convertDatum(col, val)
			if err != nil {
				return nil, err
			}

			if _, ok := primaryKeyCols[col.ID]; ok {
				// Skip primary key columns as their values are encoded in the row
//.........這裏部分代碼省略.........

// Insert inserts rows into the database.
// Privileges: WRITE on table
//   Notes: postgres requires INSERT. No "on duplicate key update" option.
//          mysql requires INSERT. Also requires UPDATE on "ON DUPLICATE KEY UPDATE".
func (p *planner) Insert(n *parser.Insert) (planNode, error) {
	tableDesc, err := p.getTableDesc(n.Table)
	if err != nil {
		return nil, err
	}

	if !tableDesc.HasPrivilege(p.user, parser.PrivilegeWrite) {
		return nil, fmt.Errorf("user %s does not have %s privilege on table %s",
			p.user, parser.PrivilegeWrite, tableDesc.Name)
	}

	// Determine which columns we're inserting into.
	cols, err := p.processColumns(tableDesc, n.Columns)
	if err != nil {
		return nil, err
	}

	// Construct a map from column ID to the index the value appears at within a
	// row.
	colIDtoRowIndex := map[structured.ID]int{}
	for i, c := range cols {
		colIDtoRowIndex[c.ID] = i
	}

	// Verify we have at least the columns that are part of the primary key.
	for i, id := range tableDesc.PrimaryIndex.ColumnIDs {
		if _, ok := colIDtoRowIndex[id]; !ok {
			return nil, fmt.Errorf("missing %q primary key column", tableDesc.PrimaryIndex.ColumnNames[i])
		}
	}

	// Transform the values into a rows object. This expands SELECT statements or
	// generates rows from the values contained within the query.
	rows, err := p.makePlan(n.Rows)
	if err != nil {
		return nil, err
	}

	primaryIndex := tableDesc.PrimaryIndex
	primaryIndexKeyPrefix := encodeIndexKeyPrefix(tableDesc.ID, primaryIndex.ID)

	b := client.Batch{}

	for rows.Next() {
		values := rows.Values()
		if len(values) != len(cols) {
			return nil, fmt.Errorf("invalid values for columns: %d != %d", len(values), len(cols))
		}

		primaryIndexKeySuffix, _, err := encodeIndexKey(primaryIndex.ColumnIDs, colIDtoRowIndex, values, nil)
		if err != nil {
			return nil, err
		}
		primaryIndexKey := bytes.Join([][]byte{primaryIndexKeyPrefix, primaryIndexKeySuffix}, nil)

		// Write the secondary indexes.
		secondaryIndexEntries, err := encodeSecondaryIndexes(tableDesc.ID, tableDesc.Indexes, colIDtoRowIndex, values, primaryIndexKeySuffix)
		if err != nil {
			return nil, err
		}

		for _, secondaryIndexEntry := range secondaryIndexEntries {
			if log.V(2) {
				log.Infof("CPut %q -> %v", secondaryIndexEntry.key, secondaryIndexEntry.value)
			}
			b.CPut(secondaryIndexEntry.key, secondaryIndexEntry.value, nil)
		}

		// Write the row.
		for i, val := range values {
			key := encodeColumnKey(cols[i], primaryIndexKey)
			if log.V(2) {
				log.Infof("CPut %q -> %v", key, val)
			}
			v, err := prepareVal(cols[i], val)
			if err != nil {
				return nil, err
			}
			b.CPut(key, v, nil)
		}
	}
	if err := rows.Err(); err != nil {
		return nil, err
	}
	if err := p.db.Run(&b); err != nil {
		if tErr, ok := err.(*proto.ConditionFailedError); ok {
			return nil, fmt.Errorf("duplicate key value %q violates unique constraint %s", tErr.ActualValue.Bytes, "TODO(tamird)")
		}
		return nil, err
	}
	// TODO(tamird/pmattis): return the number of affected rows
	return &valuesNode{}, nil
}

// RenameTable renames the table.
// Privileges: WRITE on database.
//   Notes: postgres requires the table owner.
//          mysql requires ALTER, DROP on the original table, and CREATE, INSERT
//          on the new table (and does not copy privileges over).
func (p *planner) RenameTable(n *parser.RenameTable) (planNode, error) {
	if n.NewName == "" {
		return nil, errEmptyTableName
	}

	if err := n.Name.NormalizeTableName(p.session.Database); err != nil {
		return nil, err
	}

	if n.Name.Table() == string(n.NewName) {
		// Noop.
		return &valuesNode{}, nil
	}

	dbDesc, err := p.getDatabaseDesc(n.Name.Database())
	if err != nil {
		return nil, err
	}

	tbKey := tableKey{dbDesc.ID, string(n.Name.Table())}.Key()

	// Check if table exists.
	gr, err := p.txn.Get(tbKey)
	if err != nil {
		return nil, err
	}
	if !gr.Exists() {
		if n.IfExists {
			// Noop.
			return &valuesNode{}, nil
		}
		// Key does not exist, but we want it to: error out.
		return nil, fmt.Errorf("table %q does not exist", n.Name.Table())
	}

	if err := p.checkPrivilege(dbDesc, privilege.WRITE); err != nil {
		return nil, err
	}

	tableDesc, err := p.getTableDesc(n.Name)
	if err != nil {
		return nil, err
	}

	tableDesc.SetName(string(n.NewName))

	newTbKey := tableKey{dbDesc.ID, string(n.NewName)}.Key()
	descKey := MakeDescMetadataKey(tableDesc.GetID())

	b := client.Batch{}
	b.Put(descKey, tableDesc)
	b.CPut(newTbKey, descKey, nil)
	b.Del(tbKey)
	if err := p.txn.Run(&b); err != nil {
		if _, ok := err.(*proto.ConditionFailedError); ok {
			return nil, fmt.Errorf("table name %q already exists", n.NewName)
		}
		return nil, err
	}

	return &valuesNode{}, nil
}