gitea/vendor/github.com/pingcap/tidb/executor/executor.go

1158 lines
26 KiB
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 executor
import (
"sort"
"github.com/juju/errors"
"github.com/pingcap/tidb/ast"
"github.com/pingcap/tidb/column"
"github.com/pingcap/tidb/context"
"github.com/pingcap/tidb/evaluator"
"github.com/pingcap/tidb/inspectkv"
"github.com/pingcap/tidb/kv"
"github.com/pingcap/tidb/model"
"github.com/pingcap/tidb/optimizer/plan"
"github.com/pingcap/tidb/sessionctx"
"github.com/pingcap/tidb/sessionctx/db"
"github.com/pingcap/tidb/sessionctx/forupdate"
"github.com/pingcap/tidb/table"
"github.com/pingcap/tidb/terror"
"github.com/pingcap/tidb/util/codec"
"github.com/pingcap/tidb/util/distinct"
"github.com/pingcap/tidb/util/types"
)
var (
_ Executor = &AggregateExec{}
_ Executor = &CheckTableExec{}
_ Executor = &FilterExec{}
_ Executor = &IndexRangeExec{}
_ Executor = &IndexScanExec{}
_ Executor = &LimitExec{}
_ Executor = &SelectFieldsExec{}
_ Executor = &SelectLockExec{}
_ Executor = &ShowDDLExec{}
_ Executor = &SortExec{}
_ Executor = &TableScanExec{}
)
// Error instances.
var (
ErrUnknownPlan = terror.ClassExecutor.New(CodeUnknownPlan, "Unknown plan")
ErrPrepareMulti = terror.ClassExecutor.New(CodePrepareMulti, "Can not prepare multiple statements")
ErrStmtNotFound = terror.ClassExecutor.New(CodeStmtNotFound, "Prepared statement not found")
ErrSchemaChanged = terror.ClassExecutor.New(CodeSchemaChanged, "Schema has changed")
ErrWrongParamCount = terror.ClassExecutor.New(CodeWrongParamCount, "Wrong parameter count")
)
// Error codes.
const (
CodeUnknownPlan terror.ErrCode = 1
CodePrepareMulti terror.ErrCode = 2
CodeStmtNotFound terror.ErrCode = 3
CodeSchemaChanged terror.ErrCode = 4
CodeWrongParamCount terror.ErrCode = 5
)
// Row represents a record row.
type Row struct {
// Data is the output record data for current Plan.
Data []types.Datum
RowKeys []*RowKeyEntry
}
// RowKeyEntry is designed for Delete statement in multi-table mode,
// we should know which table this row comes from.
type RowKeyEntry struct {
// The table which this row come from.
Tbl table.Table
// Row key.
Handle int64
}
// Executor executes a query.
type Executor interface {
Fields() []*ast.ResultField
Next() (*Row, error)
Close() error
}
// ShowDDLExec represents a show DDL executor.
type ShowDDLExec struct {
fields []*ast.ResultField
ctx context.Context
done bool
}
// Fields implements Executor Fields interface.
func (e *ShowDDLExec) Fields() []*ast.ResultField {
return e.fields
}
// Next implements Execution Next interface.
func (e *ShowDDLExec) Next() (*Row, error) {
if e.done {
return nil, nil
}
txn, err := e.ctx.GetTxn(false)
if err != nil {
return nil, errors.Trace(err)
}
ddlInfo, err := inspectkv.GetDDLInfo(txn)
if err != nil {
return nil, errors.Trace(err)
}
bgInfo, err := inspectkv.GetBgDDLInfo(txn)
if err != nil {
return nil, errors.Trace(err)
}
var ddlOwner, ddlJob string
if ddlInfo.Owner != nil {
ddlOwner = ddlInfo.Owner.String()
}
if ddlInfo.Job != nil {
ddlJob = ddlInfo.Job.String()
}
var bgOwner, bgJob string
if bgInfo.Owner != nil {
bgOwner = bgInfo.Owner.String()
}
if bgInfo.Job != nil {
bgJob = bgInfo.Job.String()
}
row := &Row{}
row.Data = types.MakeDatums(
ddlInfo.SchemaVer,
ddlOwner,
ddlJob,
bgInfo.SchemaVer,
bgOwner,
bgJob,
)
for i, f := range e.fields {
f.Expr.SetValue(row.Data[i].GetValue())
}
e.done = true
return row, nil
}
// Close implements Executor Close interface.
func (e *ShowDDLExec) Close() error {
return nil
}
// CheckTableExec represents a check table executor.
type CheckTableExec struct {
tables []*ast.TableName
ctx context.Context
done bool
}
// Fields implements Executor Fields interface.
func (e *CheckTableExec) Fields() []*ast.ResultField {
return nil
}
// Next implements Execution Next interface.
func (e *CheckTableExec) Next() (*Row, error) {
if e.done {
return nil, nil
}
dbName := model.NewCIStr(db.GetCurrentSchema(e.ctx))
is := sessionctx.GetDomain(e.ctx).InfoSchema()
for _, t := range e.tables {
tb, err := is.TableByName(dbName, t.Name)
if err != nil {
return nil, errors.Trace(err)
}
for _, idx := range tb.Indices() {
txn, err := e.ctx.GetTxn(false)
if err != nil {
return nil, errors.Trace(err)
}
err = inspectkv.CompareIndexData(txn, tb, idx)
if err != nil {
return nil, errors.Errorf("%v err:%v", t.Name, err)
}
}
}
e.done = true
return nil, nil
}
// Close implements plan.Plan Close interface.
func (e *CheckTableExec) Close() error {
return nil
}
// TableScanExec represents a table scan executor.
type TableScanExec struct {
t table.Table
fields []*ast.ResultField
iter kv.Iterator
ctx context.Context
ranges []plan.TableRange // Disjoint close handle ranges.
seekHandle int64 // The handle to seek, should be initialized to math.MinInt64.
cursor int // The range cursor, used to locate to current range.
}
// Fields implements Executor Fields interface.
func (e *TableScanExec) Fields() []*ast.ResultField {
return e.fields
}
// Next implements Execution Next interface.
func (e *TableScanExec) Next() (*Row, error) {
for {
if e.cursor >= len(e.ranges) {
return nil, nil
}
ran := e.ranges[e.cursor]
if e.seekHandle < ran.LowVal {
e.seekHandle = ran.LowVal
}
if e.seekHandle > ran.HighVal {
e.cursor++
continue
}
handle, found, err := e.t.Seek(e.ctx, e.seekHandle)
if err != nil {
return nil, errors.Trace(err)
}
if !found {
return nil, nil
}
if handle > ran.HighVal {
// The handle is out of the current range, but may be in following ranges.
// We seek to the range that may contains the handle, so we
// don't need to seek key again.
inRange := e.seekRange(handle)
if !inRange {
// The handle may be less than the current range low value, can not
// return directly.
continue
}
}
row, err := e.getRow(handle)
if err != nil {
return nil, errors.Trace(err)
}
e.seekHandle = handle + 1
return row, nil
}
}
// seekRange increments the range cursor to the range
// with high value greater or equal to handle.
func (e *TableScanExec) seekRange(handle int64) (inRange bool) {
for {
e.cursor++
if e.cursor >= len(e.ranges) {
return false
}
ran := e.ranges[e.cursor]
if handle < ran.LowVal {
return false
}
if handle > ran.HighVal {
continue
}
return true
}
}
func (e *TableScanExec) getRow(handle int64) (*Row, error) {
row := &Row{}
var err error
row.Data, err = e.t.Row(e.ctx, handle)
if err != nil {
return nil, errors.Trace(err)
}
// Set result fields value.
for i, v := range e.fields {
v.Expr.SetValue(row.Data[i].GetValue())
}
// Put rowKey to the tail of record row
rke := &RowKeyEntry{
Tbl: e.t,
Handle: handle,
}
row.RowKeys = append(row.RowKeys, rke)
return row, nil
}
// Close implements Executor Close interface.
func (e *TableScanExec) Close() error {
if e.iter != nil {
e.iter.Close()
e.iter = nil
}
return nil
}
// IndexRangeExec represents an index range scan executor.
type IndexRangeExec struct {
scan *IndexScanExec
// seekVal is different from lowVal, it is casted from lowVal and
// must be less than or equal to lowVal, used to seek the index.
lowVals []types.Datum
lowExclude bool
highVals []types.Datum
highExclude bool
iter kv.IndexIterator
skipLowCmp bool
finished bool
}
// Fields implements Executor Fields interface.
func (e *IndexRangeExec) Fields() []*ast.ResultField {
return e.scan.fields
}
// Next implements Executor Next interface.
func (e *IndexRangeExec) Next() (*Row, error) {
if e.iter == nil {
seekVals := make([]types.Datum, len(e.scan.idx.Columns))
for i := 0; i < len(e.lowVals); i++ {
if e.lowVals[i].Kind() == types.KindMinNotNull {
seekVals[i].SetBytes([]byte{})
} else {
val, err := e.lowVals[i].ConvertTo(e.scan.valueTypes[i])
seekVals[i] = val
if err != nil {
return nil, errors.Trace(err)
}
}
}
txn, err := e.scan.ctx.GetTxn(false)
if err != nil {
return nil, errors.Trace(err)
}
e.iter, _, err = e.scan.idx.X.Seek(txn, seekVals)
if err != nil {
return nil, types.EOFAsNil(err)
}
}
for {
if e.finished {
return nil, nil
}
idxKey, h, err := e.iter.Next()
if err != nil {
return nil, types.EOFAsNil(err)
}
if !e.skipLowCmp {
var cmp int
cmp, err = indexCompare(idxKey, e.lowVals)
if err != nil {
return nil, errors.Trace(err)
}
if cmp < 0 || (cmp == 0 && e.lowExclude) {
continue
}
e.skipLowCmp = true
}
cmp, err := indexCompare(idxKey, e.highVals)
if err != nil {
return nil, errors.Trace(err)
}
if cmp > 0 || (cmp == 0 && e.highExclude) {
// This span has finished iteration.
e.finished = true
continue
}
var row *Row
row, err = e.lookupRow(h)
if err != nil {
return nil, errors.Trace(err)
}
return row, nil
}
}
// indexCompare compares multi column index.
// The length of boundVals may be less than idxKey.
func indexCompare(idxKey []types.Datum, boundVals []types.Datum) (int, error) {
for i := 0; i < len(boundVals); i++ {
cmp, err := idxKey[i].CompareDatum(boundVals[i])
if err != nil {
return -1, errors.Trace(err)
}
if cmp != 0 {
return cmp, nil
}
}
return 0, nil
}
func (e *IndexRangeExec) lookupRow(h int64) (*Row, error) {
row := &Row{}
var err error
row.Data, err = e.scan.tbl.Row(e.scan.ctx, h)
if err != nil {
return nil, errors.Trace(err)
}
rowKey := &RowKeyEntry{
Tbl: e.scan.tbl,
Handle: h,
}
row.RowKeys = append(row.RowKeys, rowKey)
return row, nil
}
// Close implements Executor Close interface.
func (e *IndexRangeExec) Close() error {
if e.iter != nil {
e.iter.Close()
e.iter = nil
}
e.finished = false
e.skipLowCmp = false
return nil
}
// IndexScanExec represents an index scan executor.
type IndexScanExec struct {
tbl table.Table
idx *column.IndexedCol
fields []*ast.ResultField
Ranges []*IndexRangeExec
Desc bool
rangeIdx int
ctx context.Context
valueTypes []*types.FieldType
}
// Fields implements Executor Fields interface.
func (e *IndexScanExec) Fields() []*ast.ResultField {
return e.fields
}
// Next implements Executor Next interface.
func (e *IndexScanExec) Next() (*Row, error) {
for e.rangeIdx < len(e.Ranges) {
ran := e.Ranges[e.rangeIdx]
row, err := ran.Next()
if err != nil {
return nil, errors.Trace(err)
}
if row != nil {
for i, val := range row.Data {
e.fields[i].Expr.SetValue(val.GetValue())
}
return row, nil
}
ran.Close()
e.rangeIdx++
}
return nil, nil
}
// Close implements Executor Close interface.
func (e *IndexScanExec) Close() error {
for e.rangeIdx < len(e.Ranges) {
e.Ranges[e.rangeIdx].Close()
e.rangeIdx++
}
return nil
}
// JoinOuterExec represents an outer join executor.
type JoinOuterExec struct {
OuterExec Executor
InnerPlan plan.Plan
innerExec Executor
fields []*ast.ResultField
builder *executorBuilder
gotRow bool
}
// Fields implements Executor Fields interface.
func (e *JoinOuterExec) Fields() []*ast.ResultField {
return e.fields
}
// Next implements Executor Next interface.
// The data in the returned row is not used by caller.
// If inner executor didn't get any row for an outer executor row,
// a row with 0 len Data indicates there is no inner row matched for
// an outer row.
func (e *JoinOuterExec) Next() (*Row, error) {
var rowKeys []*RowKeyEntry
for {
if e.innerExec == nil {
e.gotRow = false
outerRow, err := e.OuterExec.Next()
if err != nil {
return nil, errors.Trace(err)
}
if outerRow == nil {
return nil, nil
}
rowKeys = outerRow.RowKeys
plan.Refine(e.InnerPlan)
e.innerExec = e.builder.build(e.InnerPlan)
if e.builder.err != nil {
return nil, errors.Trace(e.builder.err)
}
}
row, err := e.innerExec.Next()
if err != nil {
return nil, errors.Trace(err)
}
if row == nil {
e.innerExec.Close()
e.innerExec = nil
if e.gotRow {
continue
}
e.setInnerNull()
return &Row{RowKeys: rowKeys}, nil
}
if len(row.Data) != 0 {
e.gotRow = true
row.RowKeys = append(rowKeys, row.RowKeys...)
return row, nil
}
}
}
func (e *JoinOuterExec) setInnerNull() {
for _, rf := range e.InnerPlan.Fields() {
rf.Expr.SetValue(nil)
}
}
// Close implements Executor Close interface.
func (e *JoinOuterExec) Close() error {
err := e.OuterExec.Close()
if e.innerExec != nil {
return errors.Trace(e.innerExec.Close())
}
return errors.Trace(err)
}
// JoinInnerExec represents an inner join executor.
type JoinInnerExec struct {
InnerPlans []plan.Plan
innerExecs []Executor
Condition ast.ExprNode
ctx context.Context
fields []*ast.ResultField
builder *executorBuilder
done bool
cursor int
}
// Fields implements Executor Fields interface.
func (e *JoinInnerExec) Fields() []*ast.ResultField {
return e.fields
}
// Next implements Executor Next interface.
// The data in the returned row is not used by caller.
func (e *JoinInnerExec) Next() (*Row, error) {
if e.done {
return nil, nil
}
rowKeysSlice := make([][]*RowKeyEntry, len(e.InnerPlans))
for {
exec := e.innerExecs[e.cursor]
if exec == nil {
innerPlan := e.InnerPlans[e.cursor]
plan.Refine(innerPlan)
exec = e.builder.build(innerPlan)
if e.builder.err != nil {
return nil, errors.Trace(e.builder.err)
}
e.innerExecs[e.cursor] = exec
}
row, err := exec.Next()
if err != nil {
return nil, errors.Trace(err)
}
if row == nil {
exec.Close()
e.innerExecs[e.cursor] = nil
if e.cursor == 0 {
e.done = true
return nil, nil
}
e.cursor--
continue
}
rowKeysSlice[e.cursor] = row.RowKeys
if e.cursor < len(e.innerExecs)-1 {
e.cursor++
continue
}
var match = true
if e.Condition != nil {
match, err = evaluator.EvalBool(e.ctx, e.Condition)
if err != nil {
return nil, errors.Trace(err)
}
}
if match {
row.RowKeys = joinRowKeys(rowKeysSlice)
return row, nil
}
}
}
func joinRowKeys(rowKeysSlice [][]*RowKeyEntry) []*RowKeyEntry {
count := 0
for _, rowKeys := range rowKeysSlice {
count += len(rowKeys)
}
joined := make([]*RowKeyEntry, count)
offset := 0
for _, rowKeys := range rowKeysSlice {
copy(joined[offset:], rowKeys)
offset += len(rowKeys)
}
return joined
}
// Close implements Executor Close interface.
func (e *JoinInnerExec) Close() error {
var err error
for _, inExec := range e.innerExecs {
if inExec != nil {
e := inExec.Close()
if e != nil {
err = errors.Trace(e)
}
}
}
return err
}
// SelectFieldsExec represents a select fields executor.
type SelectFieldsExec struct {
Src Executor
ResultFields []*ast.ResultField
executed bool
ctx context.Context
}
// Fields implements Executor Fields interface.
func (e *SelectFieldsExec) Fields() []*ast.ResultField {
return e.ResultFields
}
// Next implements Executor Next interface.
func (e *SelectFieldsExec) Next() (*Row, error) {
var rowKeys []*RowKeyEntry
if e.Src != nil {
srcRow, err := e.Src.Next()
if err != nil {
return nil, errors.Trace(err)
}
if srcRow == nil {
return nil, nil
}
rowKeys = srcRow.RowKeys
} else {
// If Src is nil, only one row should be returned.
if e.executed {
return nil, nil
}
}
e.executed = true
row := &Row{
RowKeys: rowKeys,
Data: make([]types.Datum, len(e.ResultFields)),
}
for i, field := range e.ResultFields {
val, err := evaluator.Eval(e.ctx, field.Expr)
if err != nil {
return nil, errors.Trace(err)
}
row.Data[i] = types.NewDatum(val)
}
return row, nil
}
// Close implements Executor Close interface.
func (e *SelectFieldsExec) Close() error {
if e.Src != nil {
return e.Src.Close()
}
return nil
}
// FilterExec represents a filter executor.
type FilterExec struct {
Src Executor
Condition ast.ExprNode
ctx context.Context
}
// Fields implements Executor Fields interface.
func (e *FilterExec) Fields() []*ast.ResultField {
return e.Src.Fields()
}
// Next implements Executor Next interface.
func (e *FilterExec) Next() (*Row, error) {
for {
srcRow, err := e.Src.Next()
if err != nil {
return nil, errors.Trace(err)
}
if srcRow == nil {
return nil, nil
}
match, err := evaluator.EvalBool(e.ctx, e.Condition)
if err != nil {
return nil, errors.Trace(err)
}
if match {
return srcRow, nil
}
}
}
// Close implements Executor Close interface.
func (e *FilterExec) Close() error {
return e.Src.Close()
}
// SelectLockExec represents a select lock executor.
type SelectLockExec struct {
Src Executor
Lock ast.SelectLockType
ctx context.Context
}
// Fields implements Executor Fields interface.
func (e *SelectLockExec) Fields() []*ast.ResultField {
return e.Src.Fields()
}
// Next implements Executor Next interface.
func (e *SelectLockExec) Next() (*Row, error) {
row, err := e.Src.Next()
if err != nil {
return nil, errors.Trace(err)
}
if row == nil {
return nil, nil
}
if len(row.RowKeys) != 0 && e.Lock == ast.SelectLockForUpdate {
forupdate.SetForUpdate(e.ctx)
for _, k := range row.RowKeys {
err = k.Tbl.LockRow(e.ctx, k.Handle, true)
if err != nil {
return nil, errors.Trace(err)
}
}
}
return row, nil
}
// Close implements Executor Close interface.
func (e *SelectLockExec) Close() error {
return e.Src.Close()
}
// LimitExec represents limit executor
type LimitExec struct {
Src Executor
Offset uint64
Count uint64
Idx uint64
}
// Fields implements Executor Fields interface.
func (e *LimitExec) Fields() []*ast.ResultField {
return e.Src.Fields()
}
// Next implements Executor Next interface.
func (e *LimitExec) Next() (*Row, error) {
for e.Idx < e.Offset {
srcRow, err := e.Src.Next()
if err != nil {
return nil, errors.Trace(err)
}
if srcRow == nil {
return nil, nil
}
e.Idx++
}
// Negative Limit means no limit.
if e.Count >= 0 && e.Idx >= e.Offset+e.Count {
return nil, nil
}
srcRow, err := e.Src.Next()
if err != nil {
return nil, errors.Trace(err)
}
if srcRow == nil {
return nil, nil
}
e.Idx++
return srcRow, nil
}
// Close implements Executor Close interface.
func (e *LimitExec) Close() error {
return e.Src.Close()
}
// orderByRow binds a row to its order values, so it can be sorted.
type orderByRow struct {
key []interface{}
row *Row
}
// SortExec represents sorting executor.
type SortExec struct {
Src Executor
ByItems []*ast.ByItem
Rows []*orderByRow
ctx context.Context
Idx int
fetched bool
err error
}
// Fields implements Executor Fields interface.
func (e *SortExec) Fields() []*ast.ResultField {
return e.Src.Fields()
}
// Len returns the number of rows.
func (e *SortExec) Len() int {
return len(e.Rows)
}
// Swap implements sort.Interface Swap interface.
func (e *SortExec) Swap(i, j int) {
e.Rows[i], e.Rows[j] = e.Rows[j], e.Rows[i]
}
// Less implements sort.Interface Less interface.
func (e *SortExec) Less(i, j int) bool {
for index, by := range e.ByItems {
v1 := e.Rows[i].key[index]
v2 := e.Rows[j].key[index]
ret, err := types.Compare(v1, v2)
if err != nil {
e.err = err
return true
}
if by.Desc {
ret = -ret
}
if ret < 0 {
return true
} else if ret > 0 {
return false
}
}
return false
}
// Next implements Executor Next interface.
func (e *SortExec) Next() (*Row, error) {
if !e.fetched {
for {
srcRow, err := e.Src.Next()
if err != nil {
return nil, errors.Trace(err)
}
if srcRow == nil {
break
}
orderRow := &orderByRow{
row: srcRow,
key: make([]interface{}, len(e.ByItems)),
}
for i, byItem := range e.ByItems {
orderRow.key[i], err = evaluator.Eval(e.ctx, byItem.Expr)
if err != nil {
return nil, errors.Trace(err)
}
}
e.Rows = append(e.Rows, orderRow)
}
sort.Sort(e)
e.fetched = true
}
if e.err != nil {
return nil, errors.Trace(e.err)
}
if e.Idx >= len(e.Rows) {
return nil, nil
}
row := e.Rows[e.Idx].row
e.Idx++
return row, nil
}
// Close implements Executor Close interface.
func (e *SortExec) Close() error {
return e.Src.Close()
}
// For select stmt with aggregate function but without groupby clasue,
// We consider there is a single group with key singleGroup.
const singleGroup = "SingleGroup"
// AggregateExec deals with all the aggregate functions.
// It is built from Aggregate Plan. When Next() is called, it reads all the data from Src and updates all the items in AggFuncs.
// TODO: Support having.
type AggregateExec struct {
Src Executor
ResultFields []*ast.ResultField
executed bool
ctx context.Context
finish bool
AggFuncs []*ast.AggregateFuncExpr
groupMap map[string]bool
groups []string
currentGroupIndex int
GroupByItems []*ast.ByItem
}
// Fields implements Executor Fields interface.
func (e *AggregateExec) Fields() []*ast.ResultField {
return e.ResultFields
}
// Next implements Executor Next interface.
func (e *AggregateExec) Next() (*Row, error) {
// In this stage we consider all data from src as a single group.
if !e.executed {
e.groupMap = make(map[string]bool)
e.groups = []string{}
for {
hasMore, err := e.innerNext()
if err != nil {
return nil, errors.Trace(err)
}
if !hasMore {
break
}
}
e.executed = true
if (len(e.groups) == 0) && (len(e.GroupByItems) == 0) {
// If no groupby and no data, we should add an empty group.
// For example:
// "select count(c) from t;" should return one row [0]
// "select count(c) from t group by c1;" should return empty result set.
e.groups = append(e.groups, singleGroup)
}
}
if e.currentGroupIndex >= len(e.groups) {
return nil, nil
}
groupKey := e.groups[e.currentGroupIndex]
for _, af := range e.AggFuncs {
af.CurrentGroup = groupKey
}
e.currentGroupIndex++
return &Row{}, nil
}
func (e *AggregateExec) getGroupKey() (string, error) {
if len(e.GroupByItems) == 0 {
return singleGroup, nil
}
vals := make([]types.Datum, 0, len(e.GroupByItems))
for _, item := range e.GroupByItems {
v, err := evaluator.Eval(e.ctx, item.Expr)
if err != nil {
return "", errors.Trace(err)
}
vals = append(vals, types.NewDatum(v))
}
bs, err := codec.EncodeValue([]byte{}, vals...)
if err != nil {
return "", errors.Trace(err)
}
return string(bs), nil
}
// Fetch a single row from src and update each aggregate function.
// If the first return value is false, it means there is no more data from src.
func (e *AggregateExec) innerNext() (bool, error) {
if e.Src != nil {
srcRow, err := e.Src.Next()
if err != nil {
return false, errors.Trace(err)
}
if srcRow == nil {
return false, nil
}
} else {
// If Src is nil, only one row should be returned.
if e.executed {
return false, nil
}
}
e.executed = true
groupKey, err := e.getGroupKey()
if err != nil {
return false, errors.Trace(err)
}
if _, ok := e.groupMap[groupKey]; !ok {
e.groupMap[groupKey] = true
e.groups = append(e.groups, groupKey)
}
for _, af := range e.AggFuncs {
for _, arg := range af.Args {
_, err := evaluator.Eval(e.ctx, arg)
if err != nil {
return false, errors.Trace(err)
}
}
af.CurrentGroup = groupKey
af.Update()
}
return true, nil
}
// Close implements Executor Close interface.
func (e *AggregateExec) Close() error {
for _, af := range e.AggFuncs {
af.Clear()
}
if e.Src != nil {
return e.Src.Close()
}
return nil
}
// UnionExec represents union executor.
type UnionExec struct {
fields []*ast.ResultField
Sels []Executor
cursor int
}
// Fields implements Executor Fields interface.
func (e *UnionExec) Fields() []*ast.ResultField {
return e.fields
}
// Next implements Executor Next interface.
func (e *UnionExec) Next() (*Row, error) {
for {
if e.cursor >= len(e.Sels) {
return nil, nil
}
sel := e.Sels[e.cursor]
row, err := sel.Next()
if err != nil {
return nil, errors.Trace(err)
}
if row == nil {
e.cursor++
continue
}
if e.cursor != 0 {
for i := range row.Data {
// The column value should be casted as the same type of the first select statement in corresponding position
rf := e.fields[i]
var val types.Datum
val, err = row.Data[i].ConvertTo(&rf.Column.FieldType)
if err != nil {
return nil, errors.Trace(err)
}
row.Data[i] = val
}
}
for i, v := range row.Data {
e.fields[i].Expr.SetValue(v.GetValue())
}
return row, nil
}
}
// Close implements Executor Close interface.
func (e *UnionExec) Close() error {
var err error
for _, sel := range e.Sels {
er := sel.Close()
if er != nil {
err = errors.Trace(er)
}
}
return err
}
// DistinctExec represents Distinct executor.
type DistinctExec struct {
Src Executor
checker *distinct.Checker
}
// Fields implements Executor Fields interface.
func (e *DistinctExec) Fields() []*ast.ResultField {
return e.Src.Fields()
}
// Next implements Executor Next interface.
func (e *DistinctExec) Next() (*Row, error) {
if e.checker == nil {
e.checker = distinct.CreateDistinctChecker()
}
for {
row, err := e.Src.Next()
if err != nil {
return nil, errors.Trace(err)
}
if row == nil {
return nil, nil
}
ok, err := e.checker.Check(types.DatumsToInterfaces(row.Data))
if err != nil {
return nil, errors.Trace(err)
}
if !ok {
continue
}
return row, nil
}
}
// Close implements Executor Close interface.
func (e *DistinctExec) Close() error {
return e.Src.Close()
}