Golang Meta.UpdateTable方法代码示例

func (d *ddl) onModifyColumn(t *meta.Meta, job *model.Job) error {
	tblInfo, err := d.getTableInfo(t, job)
	if err != nil {
		return errors.Trace(err)
	}
	newCol := &model.ColumnInfo{}
	oldColName := &model.CIStr{}
	err = job.DecodeArgs(newCol, oldColName)
	if err != nil {
		job.State = model.JobCancelled
		return errors.Trace(err)
	}

	oldCol := findCol(tblInfo.Columns, oldColName.L)
	if oldCol == nil || oldCol.State != model.StatePublic {
		job.State = model.JobCancelled
		return infoschema.ErrColumnNotExists.GenByArgs(newCol.Name, tblInfo.Name)
	}
	*oldCol = *newCol
	err = t.UpdateTable(job.SchemaID, tblInfo)
	if err != nil {
		job.State = model.JobCancelled
		return errors.Trace(err)
	}

	ver, err := updateSchemaVersion(t, job)
	if err != nil {
		return errors.Trace(err)
	}
	job.SchemaState = model.StatePublic
	job.State = model.JobDone
	addTableHistoryInfo(job, ver, tblInfo)
	return nil
}

func (d *ddl) onDropForeignKey(t *meta.Meta, job *model.Job) error {
	schemaID := job.SchemaID
	tblInfo, err := d.getTableInfo(t, job)
	if err != nil {
		return errors.Trace(err)
	}

	var (
		fkName model.CIStr
		found  bool
		fkInfo model.FKInfo
	)
	err = job.DecodeArgs(&fkName)
	if err != nil {
		job.State = model.JobCancelled
		return errors.Trace(err)
	}

	for _, fk := range tblInfo.ForeignKeys {
		if fk.Name.L == fkName.L {
			found = true
			fkInfo = *fk
		}
	}

	if !found {
		return infoschema.ErrForeignKeyNotExists.Gen("foreign key doesn't exist", fkName)
	}

	nfks := tblInfo.ForeignKeys[:0]
	for _, fk := range tblInfo.ForeignKeys {
		if fk.Name.L != fkName.L {
			nfks = append(nfks, fk)
		}
	}
	tblInfo.ForeignKeys = nfks

	_, err = t.GenSchemaVersion()
	if err != nil {
		return errors.Trace(err)
	}

	switch fkInfo.State {
	case model.StatePublic:
		// We just support record the foreign key, so we just make it none.
		// public -> none
		job.SchemaState = model.StateNone
		fkInfo.State = model.StateNone
		err = t.UpdateTable(schemaID, tblInfo)
		if err != nil {
			return errors.Trace(err)
		}
		// finish this job
		job.State = model.JobDone
		return nil
	default:
		return ErrInvalidForeignKeyState.Gen("invalid fk state %v", fkInfo.State)
	}

}

func (d *ddl) convert2RollbackJob(t *meta.Meta, job *model.Job, tblInfo *model.TableInfo, indexInfo *model.IndexInfo) error {
	job.State = model.JobRollback
	job.Args = []interface{}{indexInfo.Name}
	// If add index job rollbacks in write reorganization state, its need to delete all keys which has been added.
	// Its work is the same as drop index job do.
	// The write reorganization state in add index job that likes write only state in drop index job.
	// So the next state is delete only state.
	indexInfo.State = model.StateDeleteOnly
	job.SchemaState = model.StateDeleteOnly
	err := t.UpdateTable(job.SchemaID, tblInfo)
	if err != nil {
		return errors.Trace(err)
	}
	err = kv.ErrKeyExists.Gen("Duplicate for key %s", indexInfo.Name.O)
	return errors.Trace(err)
}

func (d *ddl) onCreateForeignKey(t *meta.Meta, job *model.Job) error {
	schemaID := job.SchemaID
	tblInfo, err := d.getTableInfo(t, job)
	if err != nil {
		return errors.Trace(err)
	}

	var fkInfo model.FKInfo
	err = job.DecodeArgs(&fkInfo)
	if err != nil {
		job.State = model.JobCancelled
		return errors.Trace(err)
	}
	fkInfo.ID = allocateIndexID(tblInfo)
	tblInfo.ForeignKeys = append(tblInfo.ForeignKeys, &fkInfo)
	ver, err := updateSchemaVersion(t, job)
	if err != nil {
		return errors.Trace(err)
	}

	switch fkInfo.State {
	case model.StateNone:
		// We just support record the foreign key, so we just make it public.
		// none -> public
		job.SchemaState = model.StatePublic
		fkInfo.State = model.StatePublic
		err = t.UpdateTable(schemaID, tblInfo)
		if err != nil {
			return errors.Trace(err)
		}
		// Finish this job.
		job.State = model.JobDone
		addTableHistoryInfo(job, ver, tblInfo)
		return nil
	default:
		return ErrInvalidForeignKeyState.Gen("invalid fk state %v", fkInfo.State)
	}
}

func (d *ddl) onDropTable(t *meta.Meta, job *model.Job) error {
	schemaID := job.SchemaID
	tableID := job.TableID

	// Check this table's database.
	tblInfo, err := t.GetTable(schemaID, tableID)
	if terror.ErrorEqual(err, meta.ErrDBNotExists) {
		job.State = model.JobCancelled
		return errors.Trace(infoschema.ErrDatabaseNotExists)
	} else if err != nil {
		return errors.Trace(err)
	}

	// Check the table.
	if tblInfo == nil {
		job.State = model.JobCancelled
		return errors.Trace(infoschema.ErrTableNotExists)
	}

	ver, err := updateSchemaVersion(t, job)
	if err != nil {
		return errors.Trace(err)
	}

	switch tblInfo.State {
	case model.StatePublic:
		// public -> write only
		job.SchemaState = model.StateWriteOnly
		tblInfo.State = model.StateWriteOnly
		err = t.UpdateTable(schemaID, tblInfo)
	case model.StateWriteOnly:
		// write only -> delete only
		job.SchemaState = model.StateDeleteOnly
		tblInfo.State = model.StateDeleteOnly
		err = t.UpdateTable(schemaID, tblInfo)
	case model.StateDeleteOnly:
		tblInfo.State = model.StateNone
		err = t.UpdateTable(schemaID, tblInfo)
		if err = t.DropTable(job.SchemaID, job.TableID); err != nil {
			break
		}
		// Finish this job.
		job.State = model.JobDone
		job.SchemaState = model.StateNone
		addTableHistoryInfo(job, ver, tblInfo)
		startKey := tablecodec.EncodeTablePrefix(tableID)
		job.Args = append(job.Args, startKey)
	default:
		err = ErrInvalidTableState.Gen("invalid table state %v", tblInfo.State)
	}

	return errors.Trace(err)
}

func (d *ddl) onDropTable(t *meta.Meta, job *model.Job) error {
	schemaID := job.SchemaID
	tableID := job.TableID

	tblInfo, err := t.GetTable(schemaID, tableID)
	if terror.ErrorEqual(err, meta.ErrDBNotExists) {
		job.State = model.JobCancelled
		return errors.Trace(infoschema.ErrDatabaseNotExists)
	} else if err != nil {
		return errors.Trace(err)
	}

	if tblInfo == nil {
		job.State = model.JobCancelled
		return errors.Trace(infoschema.ErrTableNotExists)
	}

	_, err = t.GenSchemaVersion()
	if err != nil {
		return errors.Trace(err)
	}

	switch tblInfo.State {
	case model.StatePublic:
		// public -> write only
		job.SchemaState = model.StateWriteOnly
		tblInfo.State = model.StateWriteOnly
		err = t.UpdateTable(schemaID, tblInfo)
	case model.StateWriteOnly:
		// write only -> delete only
		job.SchemaState = model.StateDeleteOnly
		tblInfo.State = model.StateDeleteOnly
		err = t.UpdateTable(schemaID, tblInfo)
	case model.StateDeleteOnly:
		tblInfo.State = model.StateNone
		err = t.UpdateTable(schemaID, tblInfo)
		if err = t.DropTable(job.SchemaID, job.TableID); err != nil {
			break
		}
		// finish this job
		job.Args = []interface{}{tblInfo}
		job.State = model.JobDone
		job.SchemaState = model.StateNone
	default:
		err = ErrInvalidTableState.Gen("invalid table state %v", tblInfo.State)
	}

	return errors.Trace(err)
}

func (d *ddl) onDropIndex(t *meta.Meta, job *model.Job) error {
	schemaID := job.SchemaID
	tblInfo, err := d.getTableInfo(t, job)
	if err != nil {
		return errors.Trace(err)
	}

	var indexName model.CIStr
	if err = job.DecodeArgs(&indexName); err != nil {
		job.State = model.JobCancelled
		return errors.Trace(err)
	}

	var indexInfo *model.IndexInfo
	for _, idx := range tblInfo.Indices {
		if idx.Name.L == indexName.L {
			indexInfo = idx
		}
	}

	if indexInfo == nil {
		job.State = model.JobCancelled
		return ErrCantDropFieldOrKey.Gen("index %s doesn't exist", indexName)
	}

	_, err = t.GenSchemaVersion()
	if err != nil {
		return errors.Trace(err)
	}

	switch indexInfo.State {
	case model.StatePublic:
		// public -> write only
		job.SchemaState = model.StateWriteOnly
		indexInfo.State = model.StateWriteOnly
		err = t.UpdateTable(schemaID, tblInfo)
		return errors.Trace(err)
	case model.StateWriteOnly:
		// write only -> delete only
		job.SchemaState = model.StateDeleteOnly
		indexInfo.State = model.StateDeleteOnly
		err = t.UpdateTable(schemaID, tblInfo)
		return errors.Trace(err)
	case model.StateDeleteOnly:
		// delete only -> reorganization
		job.SchemaState = model.StateDeleteReorganization
		indexInfo.State = model.StateDeleteReorganization
		err = t.UpdateTable(schemaID, tblInfo)
		return errors.Trace(err)
	case model.StateDeleteReorganization:
		// reorganization -> absent
		tbl, err := d.getTable(schemaID, tblInfo)
		if err != nil {
			return errors.Trace(err)
		}

		err = d.runReorgJob(func() error {
			return d.dropTableIndex(tbl, indexInfo)
		})

		if terror.ErrorEqual(err, errWaitReorgTimeout) {
			// if timeout, we should return, check for the owner and re-wait job done.
			return nil
		}
		if err != nil {
			return errors.Trace(err)
		}

		// all reorganization jobs done, drop this index
		newIndices := make([]*model.IndexInfo, 0, len(tblInfo.Indices))
		for _, idx := range tblInfo.Indices {
			if idx.Name.L != indexName.L {
				newIndices = append(newIndices, idx)
			}
		}
		tblInfo.Indices = newIndices
		// set column index flag.
		dropIndexColumnFlag(tblInfo, indexInfo)
		if err = t.UpdateTable(schemaID, tblInfo); err != nil {
			return errors.Trace(err)
		}

		// finish this job
		job.SchemaState = model.StateNone
		job.State = model.JobDone
		return nil
	default:
		return ErrInvalidTableState.Gen("invalid table state %v", tblInfo.State)
	}
}

func (d *ddl) onCreateIndex(t *meta.Meta, job *model.Job) error {
	schemaID := job.SchemaID
	tblInfo, err := d.getTableInfo(t, job)
	if err != nil {
		return errors.Trace(err)
	}

	var (
		unique      bool
		indexName   model.CIStr
		indexID     int64
		idxColNames []*ast.IndexColName
	)

	err = job.DecodeArgs(&unique, &indexName, &indexID, &idxColNames)
	if err != nil {
		job.State = model.JobCancelled
		return errors.Trace(err)
	}

	var indexInfo *model.IndexInfo
	for _, idx := range tblInfo.Indices {
		if idx.Name.L == indexName.L {
			if idx.State == model.StatePublic {
				// we already have a index with same index name
				job.State = model.JobCancelled
				return infoschema.ErrIndexExists.Gen("CREATE INDEX: index already exist %s", indexName)
			}

			indexInfo = idx
		}
	}

	if indexInfo == nil {
		indexInfo, err = buildIndexInfo(tblInfo, unique, indexName, indexID, idxColNames)
		if err != nil {
			job.State = model.JobCancelled
			return errors.Trace(err)
		}
		tblInfo.Indices = append(tblInfo.Indices, indexInfo)
	}

	_, err = t.GenSchemaVersion()
	if err != nil {
		return errors.Trace(err)
	}

	switch indexInfo.State {
	case model.StateNone:
		// none -> delete only
		job.SchemaState = model.StateDeleteOnly
		indexInfo.State = model.StateDeleteOnly
		err = t.UpdateTable(schemaID, tblInfo)
		return errors.Trace(err)
	case model.StateDeleteOnly:
		// delete only -> write only
		job.SchemaState = model.StateWriteOnly
		indexInfo.State = model.StateWriteOnly
		err = t.UpdateTable(schemaID, tblInfo)
		return errors.Trace(err)
	case model.StateWriteOnly:
		// write only -> reorganization
		job.SchemaState = model.StateWriteReorganization
		indexInfo.State = model.StateWriteReorganization
		// initialize SnapshotVer to 0 for later reorganization check.
		job.SnapshotVer = 0
		err = t.UpdateTable(schemaID, tblInfo)
		return errors.Trace(err)
	case model.StateWriteReorganization:
		// reorganization -> public
		reorgInfo, err := d.getReorgInfo(t, job)
		if err != nil || reorgInfo.first {
			// if we run reorg firstly, we should update the job snapshot version
			// and then run the reorg next time.
			return errors.Trace(err)
		}

		var tbl table.Table
		tbl, err = d.getTable(schemaID, tblInfo)
		if err != nil {
			return errors.Trace(err)
		}

		err = d.runReorgJob(func() error {
			return d.addTableIndex(tbl, indexInfo, reorgInfo)
		})

		if terror.ErrorEqual(err, errWaitReorgTimeout) {
			// if timeout, we should return, check for the owner and re-wait job done.
			return nil
		}
		if err != nil {
			return errors.Trace(err)
		}

		indexInfo.State = model.StatePublic
		// set column index flag.
		addIndexColumnFlag(tblInfo, indexInfo)
		if err = t.UpdateTable(schemaID, tblInfo); err != nil {
			return errors.Trace(err)
//.........这里部分代码省略.........

func (d *ddl) onDropTable(t *meta.Meta, job *model.Job) error {
	schemaID := job.SchemaID
	tableID := job.TableID

	tblInfo, err := t.GetTable(schemaID, tableID)
	if terror.ErrorEqual(err, meta.ErrDBNotExists) {
		job.State = model.JobCancelled
		return errors.Trace(terror.DatabaseNotExists)
	} else if err != nil {
		return errors.Trace(err)
	}

	if tblInfo == nil {
		job.State = model.JobCancelled
		return errors.Trace(ErrNotExists)
	}

	_, err = t.GenSchemaVersion()
	if err != nil {
		return errors.Trace(err)
	}

	switch tblInfo.State {
	case model.StatePublic:
		// public -> write only
		job.SchemaState = model.StateWriteOnly
		tblInfo.State = model.StateWriteOnly
		err = t.UpdateTable(schemaID, tblInfo)
		return errors.Trace(err)
	case model.StateWriteOnly:
		// write only -> delete only
		job.SchemaState = model.StateDeleteOnly
		tblInfo.State = model.StateDeleteOnly
		err = t.UpdateTable(schemaID, tblInfo)
		return errors.Trace(err)
	case model.StateDeleteOnly:
		// delete only -> reorganization
		job.SchemaState = model.StateDeleteReorganization
		tblInfo.State = model.StateDeleteReorganization
		err = t.UpdateTable(schemaID, tblInfo)
		return errors.Trace(err)
	case model.StateDeleteReorganization:
		// reorganization -> absent
		var tbl table.Table
		tbl, err = d.getTable(t, schemaID, tblInfo)
		if err != nil {
			return errors.Trace(err)
		}

		err = d.runReorgJob(func() error {
			return d.dropTableData(tbl)
		})

		if terror.ErrorEqual(err, errWaitReorgTimeout) {
			// if timeout, we should return, check for the owner and re-wait job done.
			return nil
		}
		if err != nil {
			return errors.Trace(err)
		}

		// all reorganization jobs done, drop this database
		if err = t.DropTable(schemaID, tableID); err != nil {
			return errors.Trace(err)
		}

		// finish this job
		job.SchemaState = model.StateNone
		job.State = model.JobDone
		return nil
	default:
		return errors.Errorf("invalid table state %v", tblInfo.State)
	}
}

func (d *ddl) onAddColumn(t *meta.Meta, job *model.Job) error {
	schemaID := job.SchemaID
	tblInfo, err := d.getTableInfo(t, job)
	if err != nil {
		return errors.Trace(err)
	}

	col := &model.ColumnInfo{}
	pos := &ColumnPosition{}
	offset := 0
	err = job.DecodeArgs(col, pos, &offset)
	if err != nil {
		job.State = model.JobCancelled
		return errors.Trace(err)
	}

	columnInfo := findCol(tblInfo.Columns, col.Name.L)
	if columnInfo != nil {
		if columnInfo.State == model.StatePublic {
			// we already have a column with same column name
			job.State = model.JobCancelled
			return errors.Errorf("ADD COLUMN: column already exist %s", col.Name.L)
		}
	} else {
		columnInfo, offset, err = d.addColumn(tblInfo, col, pos)
		if err != nil {
			job.State = model.JobCancelled
			return errors.Trace(err)
		}

		// Set offset arg to job.
		if offset != 0 {
			job.Args = []interface{}{columnInfo, pos, offset}
		}
	}

	_, err = t.GenSchemaVersion()
	if err != nil {
		return errors.Trace(err)
	}

	switch columnInfo.State {
	case model.StateNone:
		// none -> delete only
		job.SchemaState = model.StateDeleteOnly
		columnInfo.State = model.StateDeleteOnly
		err = t.UpdateTable(schemaID, tblInfo)
		return errors.Trace(err)
	case model.StateDeleteOnly:
		// delete only -> write only
		job.SchemaState = model.StateWriteOnly
		columnInfo.State = model.StateWriteOnly
		err = t.UpdateTable(schemaID, tblInfo)
		return errors.Trace(err)
	case model.StateWriteOnly:
		// write only -> reorganization
		job.SchemaState = model.StateWriteReorganization
		columnInfo.State = model.StateWriteReorganization
		// initialize SnapshotVer to 0 for later reorganization check.
		job.SnapshotVer = 0
		err = t.UpdateTable(schemaID, tblInfo)
		return errors.Trace(err)
	case model.StateWriteReorganization:
		// reorganization -> public
		// get the current version for reorganization if we don't have
		reorgInfo, err := d.getReorgInfo(t, job)
		if err != nil || reorgInfo.first {
			// if we run reorg firstly, we should update the job snapshot version
			// and then run the reorg next time.
			return errors.Trace(err)
		}

		tbl, err := d.getTable(schemaID, tblInfo)
		if err != nil {
			return errors.Trace(err)
		}

		err = d.runReorgJob(func() error {
			return d.backfillColumn(tbl, columnInfo, reorgInfo)
		})

		if terror.ErrorEqual(err, errWaitReorgTimeout) {
			// if timeout, we should return, check for the owner and re-wait job done.
			return nil
		}
		if err != nil {
			return errors.Trace(err)
		}

		// Adjust column offset.
		d.adjustColumnOffset(tblInfo.Columns, tblInfo.Indices, offset, true)

		columnInfo.State = model.StatePublic

		if err = t.UpdateTable(schemaID, tblInfo); err != nil {
			return errors.Trace(err)
		}

		// finish this job
		job.SchemaState = model.StatePublic
//.........这里部分代码省略.........

func (d *ddl) onDropColumn(t *meta.Meta, job *model.Job) error {
	schemaID := job.SchemaID
	tblInfo, err := d.getTableInfo(t, job)
	if err != nil {
		return errors.Trace(err)
	}

	var colName model.CIStr
	err = job.DecodeArgs(&colName)
	if err != nil {
		job.State = model.JobCancelled
		return errors.Trace(err)
	}

	colInfo := findCol(tblInfo.Columns, colName.L)
	if colInfo == nil {
		job.State = model.JobCancelled
		return errors.Errorf("column %s doesn't exist", colName)
	}

	if len(tblInfo.Columns) == 1 {
		job.State = model.JobCancelled
		return errors.Errorf("can't drop only column %s in table %s", colName, tblInfo.Name)
	}

	// we don't support drop column with index covered now.
	// we must drop the index first, then drop the column.
	for _, indexInfo := range tblInfo.Indices {
		for _, col := range indexInfo.Columns {
			if col.Name.L == colName.L {
				job.State = model.JobCancelled
				return errors.Errorf("can't drop column %s with index %s covered now", colName, indexInfo.Name)
			}
		}
	}

	_, err = t.GenSchemaVersion()
	if err != nil {
		return errors.Trace(err)
	}

	switch colInfo.State {
	case model.StatePublic:
		// public -> write only
		job.SchemaState = model.StateWriteOnly
		colInfo.State = model.StateWriteOnly

		// set this column's offset to the last and reset all following columns' offset
		d.adjustColumnOffset(tblInfo.Columns, tblInfo.Indices, colInfo.Offset, false)

		err = t.UpdateTable(schemaID, tblInfo)
		return errors.Trace(err)
	case model.StateWriteOnly:
		// write only -> delete only
		job.SchemaState = model.StateDeleteOnly
		colInfo.State = model.StateDeleteOnly
		err = t.UpdateTable(schemaID, tblInfo)
		return errors.Trace(err)
	case model.StateDeleteOnly:
		// delete only -> reorganization
		job.SchemaState = model.StateDeleteReorganization
		colInfo.State = model.StateDeleteReorganization
		// initialize SnapshotVer to 0 for later reorganization check.
		job.SnapshotVer = 0
		err = t.UpdateTable(schemaID, tblInfo)
		return errors.Trace(err)
	case model.StateDeleteReorganization:
		// reorganization -> absent
		reorgInfo, err := d.getReorgInfo(t, job)
		if err != nil || reorgInfo.first {
			// if we run reorg firstly, we should update the job snapshot version
			// and then run the reorg next time.
			return errors.Trace(err)
		}

		tbl, err := d.getTable(schemaID, tblInfo)
		if err != nil {
			return errors.Trace(err)
		}

		err = d.runReorgJob(func() error {
			return d.dropTableColumn(tbl, colInfo, reorgInfo)
		})

		if terror.ErrorEqual(err, errWaitReorgTimeout) {
			// if timeout, we should return, check for the owner and re-wait job done.
			return nil
		}
		if err != nil {
			return errors.Trace(err)
		}

		// all reorganization jobs done, drop this column
		newColumns := make([]*model.ColumnInfo, 0, len(tblInfo.Columns))
		for _, col := range tblInfo.Columns {
			if col.Name.L != colName.L {
				newColumns = append(newColumns, col)
			}
		}
		tblInfo.Columns = newColumns
//.........这里部分代码省略.........

func (d *ddl) onAddColumn(t *meta.Meta, job *model.Job) error {
	schemaID := job.SchemaID
	tblInfo, err := d.getTableInfo(t, job)
	if err != nil {
		return errors.Trace(err)
	}

	col := &model.ColumnInfo{}
	pos := &ast.ColumnPosition{}
	offset := 0
	err = job.DecodeArgs(col, pos, &offset)
	if err != nil {
		job.State = model.JobCancelled
		return errors.Trace(err)
	}

	columnInfo := findCol(tblInfo.Columns, col.Name.L)
	if columnInfo != nil {
		if columnInfo.State == model.StatePublic {
			// We already have a column with the same column name.
			job.State = model.JobCancelled
			return infoschema.ErrColumnExists.GenByArgs(col.Name)
		}
	} else {
		columnInfo, offset, err = d.createColumnInfo(tblInfo, col, pos)
		if err != nil {
			job.State = model.JobCancelled
			return errors.Trace(err)
		}
		// Set offset arg to job.
		if offset != 0 {
			job.Args = []interface{}{columnInfo, pos, offset}
		}
	}

	ver, err := updateSchemaVersion(t, job)
	if err != nil {
		return errors.Trace(err)
	}

	switch columnInfo.State {
	case model.StateNone:
		// none -> delete only
		job.SchemaState = model.StateDeleteOnly
		columnInfo.State = model.StateDeleteOnly
		err = t.UpdateTable(schemaID, tblInfo)
	case model.StateDeleteOnly:
		// delete only -> write only
		job.SchemaState = model.StateWriteOnly
		columnInfo.State = model.StateWriteOnly
		err = t.UpdateTable(schemaID, tblInfo)
	case model.StateWriteOnly:
		// write only -> reorganization
		job.SchemaState = model.StateWriteReorganization
		columnInfo.State = model.StateWriteReorganization
		// Initialize SnapshotVer to 0 for later reorganization check.
		job.SnapshotVer = 0
		err = t.UpdateTable(schemaID, tblInfo)
	case model.StateWriteReorganization:
		// reorganization -> public
		// Get the current version for reorganization if we don't have it.
		reorgInfo, err := d.getReorgInfo(t, job)
		if err != nil || reorgInfo.first {
			// If we run reorg firstly, we should update the job snapshot version
			// and then run the reorg next time.
			return errors.Trace(err)
		}

		tbl, err := d.getTable(schemaID, tblInfo)
		if err != nil {
			return errors.Trace(err)
		}
		if columnInfo.DefaultValue != nil || mysql.HasNotNullFlag(columnInfo.Flag) {
			err = d.runReorgJob(func() error {
				return d.addTableColumn(tbl, columnInfo, reorgInfo, job)
			})
			if terror.ErrorEqual(err, errWaitReorgTimeout) {
				// If the timeout happens, we should return.
				// Then check for the owner and re-wait job to finish.
				return nil
			}
			if err != nil {
				return errors.Trace(err)
			}
		}

		// Adjust column offset.
		d.adjustColumnOffset(tblInfo.Columns, tblInfo.Indices, offset, true)
		columnInfo.State = model.StatePublic
		if err = t.UpdateTable(schemaID, tblInfo); err != nil {
			return errors.Trace(err)
		}

		// Finish this job.
		job.SchemaState = model.StatePublic
		job.State = model.JobDone
		addTableHistoryInfo(job, ver, tblInfo)
	default:
		err = ErrInvalidColumnState.Gen("invalid column state %v", columnInfo.State)
	}
//.........这里部分代码省略.........

func (d *ddl) onDropColumn(t *meta.Meta, job *model.Job) error {
	schemaID := job.SchemaID
	tblInfo, err := d.getTableInfo(t, job)
	if err != nil {
		return errors.Trace(err)
	}

	var colName model.CIStr
	err = job.DecodeArgs(&colName)
	if err != nil {
		job.State = model.JobCancelled
		return errors.Trace(err)
	}

	colInfo := findCol(tblInfo.Columns, colName.L)
	if colInfo == nil {
		job.State = model.JobCancelled
		return ErrCantDropFieldOrKey.Gen("column %s doesn't exist", colName)
	}

	if len(tblInfo.Columns) == 1 {
		job.State = model.JobCancelled
		return ErrCantRemoveAllFields.Gen("can't drop only column %s in table %s",
			colName, tblInfo.Name)
	}

	// We don't support dropping column with index covered now.
	if isColumnWithIndex(colName.L, tblInfo.Indices) {
		job.State = model.JobCancelled
		return errCantDropColWithIndex.Gen("can't drop column %s with index covered now", colName)
	}

	ver, err := updateSchemaVersion(t, job)
	if err != nil {
		return errors.Trace(err)
	}

	switch colInfo.State {
	case model.StatePublic:
		// public -> write only
		job.SchemaState = model.StateWriteOnly
		colInfo.State = model.StateWriteOnly
		// Set this column's offset to the last and reset all following columns' offsets.
		d.adjustColumnOffset(tblInfo.Columns, tblInfo.Indices, colInfo.Offset, false)
		err = t.UpdateTable(schemaID, tblInfo)
	case model.StateWriteOnly:
		// write only -> delete only
		job.SchemaState = model.StateDeleteOnly
		colInfo.State = model.StateDeleteOnly
		err = t.UpdateTable(schemaID, tblInfo)
	case model.StateDeleteOnly:
		// delete only -> reorganization
		job.SchemaState = model.StateDeleteReorganization
		colInfo.State = model.StateDeleteReorganization
		// Initialize SnapshotVer to 0 for later reorganization check.
		job.SnapshotVer = 0
		err = t.UpdateTable(schemaID, tblInfo)
	case model.StateDeleteReorganization:
		// reorganization -> absent
		reorgInfo, err := d.getReorgInfo(t, job)
		if err != nil || reorgInfo.first {
			// If we run reorg firstly, we should update the job snapshot version
			// and then run the reorg next time.
			return errors.Trace(err)
		}

		// All reorganization jobs are done, drop this column.
		newColumns := make([]*model.ColumnInfo, 0, len(tblInfo.Columns))
		for _, col := range tblInfo.Columns {
			if col.Name.L != colName.L {
				newColumns = append(newColumns, col)
			}
		}
		tblInfo.Columns = newColumns
		if err = t.UpdateTable(schemaID, tblInfo); err != nil {
			return errors.Trace(err)
		}

		// Finish this job.
		job.SchemaState = model.StateNone
		job.State = model.JobDone
		addTableHistoryInfo(job, ver, tblInfo)
	default:
		err = ErrInvalidTableState.Gen("invalid table state %v", tblInfo.State)
	}
	return errors.Trace(err)
}

func (d *ddl) onCreateTable(t *meta.Meta, job *model.Job) error {
	schemaID := job.SchemaID
	tbInfo := &model.TableInfo{}
	if err := job.DecodeArgs(tbInfo); err != nil {
		// arg error, cancel this job.
		job.State = model.JobCancelled
		return errors.Trace(err)
	}

	tbInfo.State = model.StateNone

	tables, err := t.ListTables(schemaID)
	if terror.ErrorEqual(err, meta.ErrDBNotExists) {
		job.State = model.JobCancelled
		return errors.Trace(terror.DatabaseNotExists)
	} else if err != nil {
		return errors.Trace(err)
	}

	for _, tbl := range tables {
		if tbl.Name.L == tbInfo.Name.L {
			if tbl.ID != tbInfo.ID {
				// table exists, can't create, we should cancel this job now.
				job.State = model.JobCancelled
				return errors.Trace(ErrExists)
			}

			tbInfo = tbl
		}
	}

	_, err = t.GenSchemaVersion()
	if err != nil {
		return errors.Trace(err)
	}

	switch tbInfo.State {
	case model.StateNone:
		// none -> delete only
		job.SchemaState = model.StateDeleteOnly
		tbInfo.State = model.StateDeleteOnly
		err = t.CreateTable(schemaID, tbInfo)
		return errors.Trace(err)
	case model.StateDeleteOnly:
		// delete only -> write only
		job.SchemaState = model.StateWriteOnly
		tbInfo.State = model.StateWriteOnly
		err = t.UpdateTable(schemaID, tbInfo)
		return errors.Trace(err)
	case model.StateWriteOnly:
		// write only -> public
		job.SchemaState = model.StatePublic
		tbInfo.State = model.StatePublic
		err = t.UpdateTable(schemaID, tbInfo)
		if err != nil {
			return errors.Trace(err)
		}

		// finish this job
		job.State = model.JobDone
		return nil
	default:
		return errors.Errorf("invalid table state %v", tbInfo.State)
	}
}

func (d *ddl) onDropIndex(t *meta.Meta, job *model.Job) error {
	schemaID := job.SchemaID
	tblInfo, err := d.getTableInfo(t, job)
	if err != nil {
		return errors.Trace(err)
	}

	var indexName model.CIStr
	if err = job.DecodeArgs(&indexName); err != nil {
		job.State = model.JobCancelled
		return errors.Trace(err)
	}

	indexInfo := findIndexByName(indexName.L, tblInfo.Indices)
	if indexInfo == nil {
		job.State = model.JobCancelled
		return ErrCantDropFieldOrKey.Gen("index %s doesn't exist", indexName)
	}

	ver, err := updateSchemaVersion(t, job)
	if err != nil {
		return errors.Trace(err)
	}

	switch indexInfo.State {
	case model.StatePublic:
		// public -> write only
		job.SchemaState = model.StateWriteOnly
		indexInfo.State = model.StateWriteOnly
		err = t.UpdateTable(schemaID, tblInfo)
	case model.StateWriteOnly:
		// write only -> delete only
		job.SchemaState = model.StateDeleteOnly
		indexInfo.State = model.StateDeleteOnly
		err = t.UpdateTable(schemaID, tblInfo)
	case model.StateDeleteOnly:
		// delete only -> reorganization
		job.SchemaState = model.StateDeleteReorganization
		indexInfo.State = model.StateDeleteReorganization
		err = t.UpdateTable(schemaID, tblInfo)
	case model.StateDeleteReorganization:
		// reorganization -> absent
		err = d.runReorgJob(func() error {
			return d.dropTableIndex(indexInfo, job)
		})
		if terror.ErrorEqual(err, errWaitReorgTimeout) {
			// If the timeout happens, we should return.
			// Then check for the owner and re-wait job to finish.
			return nil
		}
		if err != nil {
			return errors.Trace(err)
		}

		// All reorganization jobs are done, drop this index.
		newIndices := make([]*model.IndexInfo, 0, len(tblInfo.Indices))
		for _, idx := range tblInfo.Indices {
			if idx.Name.L != indexName.L {
				newIndices = append(newIndices, idx)
			}
		}
		tblInfo.Indices = newIndices
		// Set column index flag.
		dropIndexColumnFlag(tblInfo, indexInfo)
		if err = t.UpdateTable(schemaID, tblInfo); err != nil {
			return errors.Trace(err)
		}

		// Finish this job.
		job.SchemaState = model.StateNone
		if job.State == model.JobRollback {
			job.State = model.JobRollbackDone
		} else {
			job.State = model.JobDone
		}
		addTableHistoryInfo(job, ver, tblInfo)
	default:
		err = ErrInvalidTableState.Gen("invalid table state %v", tblInfo.State)
	}
	return errors.Trace(err)
}