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gitea/vendor/github.com/pingcap/tidb/ddl/column.go

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Go

// Copyright 2015 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
package ddl
import (
"github.com/juju/errors"
"github.com/ngaut/log"
"github.com/pingcap/tidb/ast"
"github.com/pingcap/tidb/column"
"github.com/pingcap/tidb/kv"
"github.com/pingcap/tidb/meta"
"github.com/pingcap/tidb/model"
"github.com/pingcap/tidb/table"
"github.com/pingcap/tidb/table/tables"
"github.com/pingcap/tidb/terror"
)
func (d *ddl) adjustColumnOffset(columns []*model.ColumnInfo, indices []*model.IndexInfo, offset int, added bool) {
offsetChanged := make(map[int]int)
if added {
for i := offset + 1; i < len(columns); i++ {
offsetChanged[columns[i].Offset] = i
columns[i].Offset = i
}
columns[offset].Offset = offset
} else {
for i := offset + 1; i < len(columns); i++ {
offsetChanged[columns[i].Offset] = i - 1
columns[i].Offset = i - 1
}
columns[offset].Offset = len(columns) - 1
}
// TODO: index can't cover the add/remove column with offset now, we may check this later.
// Update index column offset info.
for _, idx := range indices {
for _, col := range idx.Columns {
newOffset, ok := offsetChanged[col.Offset]
if ok {
col.Offset = newOffset
}
}
}
}
func (d *ddl) addColumn(tblInfo *model.TableInfo, colInfo *model.ColumnInfo, pos *ast.ColumnPosition) (*model.ColumnInfo, int, error) {
// Check column name duplicate.
cols := tblInfo.Columns
position := len(cols)
// Get column position.
if pos.Tp == ast.ColumnPositionFirst {
position = 0
} else if pos.Tp == ast.ColumnPositionAfter {
c := findCol(cols, pos.RelativeColumn.Name.L)
if c == nil {
return nil, 0, errors.Errorf("No such column: %v", pos.RelativeColumn)
}
// Insert position is after the mentioned column.
position = c.Offset + 1
}
colInfo.State = model.StateNone
// To support add column asynchronous, we should mark its offset as the last column.
// So that we can use origin column offset to get value from row.
colInfo.Offset = len(cols)
// Insert col into the right place of the column list.
newCols := make([]*model.ColumnInfo, 0, len(cols)+1)
newCols = append(newCols, cols[:position]...)
newCols = append(newCols, colInfo)
newCols = append(newCols, cols[position:]...)
tblInfo.Columns = newCols
return colInfo, position, nil
}
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 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
job.State = model.JobDone
return nil
default:
return errors.Errorf("invalid column state %v", columnInfo.State)
}
}
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
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 errors.Errorf("invalid table state %v", tblInfo.State)
}
}
// How to backfill column data in reorganization state?
// 1. Generate a snapshot with special version.
// 2. Traverse the snapshot, get every row in the table.
// 3. For one row, if the row has been already deleted, skip to next row.
// 4. If not deleted, check whether column data has existed, if existed, skip to next row.
// 5. If column data doesn't exist, backfill the column with default value and then continue to handle next row.
func (d *ddl) backfillColumn(t table.Table, columnInfo *model.ColumnInfo, reorgInfo *reorgInfo) error {
seekHandle := reorgInfo.Handle
version := reorgInfo.SnapshotVer
for {
handles, err := d.getSnapshotRows(t, version, seekHandle)
if err != nil {
return errors.Trace(err)
} else if len(handles) == 0 {
return nil
}
seekHandle = handles[len(handles)-1] + 1
err = d.backfillColumnData(t, columnInfo, handles, reorgInfo)
if err != nil {
return errors.Trace(err)
}
}
}
func (d *ddl) backfillColumnData(t table.Table, columnInfo *model.ColumnInfo, handles []int64, reorgInfo *reorgInfo) error {
for _, handle := range handles {
log.Info("[ddl] backfill column...", handle)
err := kv.RunInNewTxn(d.store, true, func(txn kv.Transaction) error {
if err := d.isReorgRunnable(txn); err != nil {
return errors.Trace(err)
}
// First check if row exists.
exist, err := checkRowExist(txn, t, handle)
if err != nil {
return errors.Trace(err)
} else if !exist {
// If row doesn't exist, skip it.
return nil
}
backfillKey := t.RecordKey(handle, &column.Col{ColumnInfo: *columnInfo})
backfillValue, err := txn.Get(backfillKey)
if err != nil && !kv.IsErrNotFound(err) {
return errors.Trace(err)
}
if backfillValue != nil {
return nil
}
value, _, err := table.GetColDefaultValue(nil, columnInfo)
if err != nil {
return errors.Trace(err)
}
// must convert to the column field type.
v, err := value.ConvertTo(&columnInfo.FieldType)
if err != nil {
return errors.Trace(err)
}
err = lockRow(txn, t, handle)
if err != nil {
return errors.Trace(err)
}
err = tables.SetColValue(txn, backfillKey, v)
if err != nil {
return errors.Trace(err)
}
return errors.Trace(reorgInfo.UpdateHandle(txn, handle))
})
if err != nil {
return errors.Trace(err)
}
}
return nil
}
func (d *ddl) dropTableColumn(t table.Table, colInfo *model.ColumnInfo, reorgInfo *reorgInfo) error {
version := reorgInfo.SnapshotVer
seekHandle := reorgInfo.Handle
col := &column.Col{ColumnInfo: *colInfo}
for {
handles, err := d.getSnapshotRows(t, version, seekHandle)
if err != nil {
return errors.Trace(err)
} else if len(handles) == 0 {
return nil
}
seekHandle = handles[len(handles)-1] + 1
err = kv.RunInNewTxn(d.store, true, func(txn kv.Transaction) error {
if err1 := d.isReorgRunnable(txn); err1 != nil {
return errors.Trace(err1)
}
var h int64
for _, h = range handles {
key := t.RecordKey(h, col)
err1 := txn.Delete(key)
if err1 != nil && !terror.ErrorEqual(err1, kv.ErrNotExist) {
return errors.Trace(err1)
}
}
return errors.Trace(reorgInfo.UpdateHandle(txn, h))
})
if err != nil {
return errors.Trace(err)
}
}
}