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truncate.go
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truncate.go
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// Copyright 2020-2021 Dolthub, 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,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package plan
import (
"gopkg.in/src-d/go-errors.v1"
"github.com/Sndav/go-mysql-server/sql"
)
var ErrTruncateNotSupported = errors.NewKind("table doesn't support TRUNCATE")
// Truncate is a node describing the deletion of all rows from some table.
type Truncate struct {
db string
UnaryNode
}
var _ sql.Node = (*Truncate)(nil)
var _ sql.DebugStringer = (*Truncate)(nil)
// NewTruncate creates a Truncate node.
func NewTruncate(db string, table sql.Node) *Truncate {
return &Truncate{
db: db,
UnaryNode: UnaryNode{table},
}
}
func GetTruncatable(node sql.Node) (sql.TruncateableTable, error) {
switch node := node.(type) {
case sql.TruncateableTable:
return node, nil
case *IndexedTableAccess:
return GetTruncatable(node.ResolvedTable)
case *ResolvedTable:
return getTruncatableTable(node.Table)
case sql.TableWrapper:
return getTruncatableTable(node.Underlying())
}
for _, child := range node.Children() {
truncater, _ := GetTruncatable(child)
if truncater != nil {
return truncater, nil
}
}
return nil, ErrTruncateNotSupported.New()
}
func getTruncatableTable(t sql.Table) (sql.TruncateableTable, error) {
switch t := t.(type) {
case sql.TruncateableTable:
return t, nil
case sql.TableWrapper:
return getTruncatableTable(t.Underlying())
default:
return nil, ErrTruncateNotSupported.New()
}
}
// DatabaseName returns the name of the database that this operation is being performed in.
func (p *Truncate) DatabaseName() string {
return p.db
}
// RowIter implements the Node interface.
func (p *Truncate) RowIter(ctx *sql.Context, _ sql.Row) (sql.RowIter, error) {
truncatable, err := GetTruncatable(p.Child)
if err != nil {
return nil, err
}
//TODO: when performance schema summary tables are added, reset the columns to 0/NULL rather than remove rows
//TODO: close all handlers that were opened with "HANDLER OPEN"
removed, err := truncatable.Truncate(ctx)
if err != nil {
return nil, err
}
for _, col := range truncatable.Schema() {
if col.AutoIncrement {
aiTable, ok := truncatable.(sql.AutoIncrementTable)
if ok {
setter := aiTable.AutoIncrementSetter(ctx)
err = setter.SetAutoIncrementValue(ctx, p.incrementAutoIncrementZero(col.Type.Zero()))
if err != nil {
return nil, err
}
err = setter.Close(ctx)
if err != nil {
return nil, err
}
}
break
}
}
return sql.RowsToRowIter(sql.NewRow(sql.NewOkResult(removed))), nil
}
// incrementAutoIncrementZero returns the starting value for an auto_increment column once truncated.
func (p *Truncate) incrementAutoIncrementZero(v interface{}) interface{} {
switch val := v.(type) {
case int:
return val + 1
case uint:
return val + 1
case int8:
return val + 1
case int16:
return val + 1
case int32:
return val + 1
case int64:
return val + 1
case uint8:
return val + 1
case uint16:
return val + 1
case uint32:
return val + 1
case uint64:
return val + 1
case float32:
return val + 1
case float64:
return val + 1
}
return v
}
// Schema implements the Node interface.
func (p *Truncate) Schema() sql.Schema {
return sql.OkResultSchema
}
// WithChildren implements the Node interface.
func (p *Truncate) WithChildren(children ...sql.Node) (sql.Node, error) {
if len(children) != 1 {
return nil, sql.ErrInvalidChildrenNumber.New(p, len(children), 1)
}
nt := *p
nt.UnaryNode = UnaryNode{children[0]}
return &nt, nil
}
// String implements the Node interface.
func (p Truncate) String() string {
pr := sql.NewTreePrinter()
_ = pr.WriteNode("Truncate")
_ = pr.WriteChildren(p.Child.String())
return pr.String()
}
// DebugString implements the DebugStringer interface.
func (p Truncate) DebugString() string {
pr := sql.NewTreePrinter()
_ = pr.WriteNode("Truncate")
_ = pr.WriteChildren(sql.DebugString(p.Child))
return pr.String()
}