tidb optimize 源码
tidb optimize 代码
文件路径：/planner/optimize.go
// Copyright 2018 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,
// 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 planner
import (
"context"
"fmt"
"math"
"math/rand"
"strings"
"sync"
"time"
"github.com/pingcap/errors"
"github.com/pingcap/failpoint"
"github.com/pingcap/tidb/bindinfo"
"github.com/pingcap/tidb/domain"
"github.com/pingcap/tidb/infoschema"
"github.com/pingcap/tidb/kv"
"github.com/pingcap/tidb/metrics"
"github.com/pingcap/tidb/parser"
"github.com/pingcap/tidb/parser/ast"
"github.com/pingcap/tidb/planner/cascades"
"github.com/pingcap/tidb/planner/core"
"github.com/pingcap/tidb/privilege"
"github.com/pingcap/tidb/sessionctx"
"github.com/pingcap/tidb/sessionctx/stmtctx"
"github.com/pingcap/tidb/sessionctx/variable"
"github.com/pingcap/tidb/sessiontxn"
"github.com/pingcap/tidb/types"
"github.com/pingcap/tidb/util/hint"
"github.com/pingcap/tidb/util/logutil"
utilparser "github.com/pingcap/tidb/util/parser"
"github.com/pingcap/tidb/util/topsql"
"go.uber.org/zap"
)
// IsReadOnly check whether the ast.Node is a read only statement.
func IsReadOnly(node ast.Node, vars *variable.SessionVars) bool {
if execStmt, isExecStmt := node.(*ast.ExecuteStmt); isExecStmt {
prepareStmt, err := core.GetPreparedStmt(execStmt, vars)
if err != nil {
logutil.BgLogger().Warn("GetPreparedStmt failed", zap.Error(err))
return false
}
return ast.IsReadOnly(prepareStmt.PreparedAst.Stmt)
}
return ast.IsReadOnly(node)
}
func matchSQLBinding(sctx sessionctx.Context, stmtNode ast.StmtNode) (bindRecord *bindinfo.BindRecord, scope string, matched bool) {
useBinding := sctx.GetSessionVars().UsePlanBaselines
if !useBinding || stmtNode == nil {
return nil, "", false
}
var err error
bindRecord, scope, err = getBindRecord(sctx, stmtNode)
if err != nil || bindRecord == nil || len(bindRecord.Bindings) == 0 {
return nil, "", false
}
return bindRecord, scope, true
}
// getPlanFromGeneralPlanCache tries to get an available cached plan from the General Plan Cache for this stmt.
func getPlanFromGeneralPlanCache(ctx context.Context, sctx sessionctx.Context, stmt ast.StmtNode, is infoschema.InfoSchema) (core.Plan, types.NameSlice, bool, error) {
if sctx.GetSessionVars().StmtCtx.InPreparedPlanBuilding || // already in cached plan rebuilding phase
!core.GeneralPlanCacheableWithCtx(sctx, stmt, is) {
return nil, nil, false, nil
}
paramSQL, params, err := core.ParameterizeAST(sctx, stmt)
if err != nil {
return nil, nil, false, err
}
val := sctx.GetSessionVars().GetGeneralPlanCacheStmt(paramSQL)
if val == nil {
cachedStmt, _, _, err := core.GeneratePlanCacheStmtWithAST(ctx, sctx, stmt)
if err != nil {
return nil, nil, false, err
}
sctx.GetSessionVars().AddGeneralPlanCacheStmt(paramSQL, cachedStmt)
val = cachedStmt
}
cachedStmt := val.(*core.PlanCacheStmt)
paramExprs := core.Params2Expressions(params)
cachedPlan, names, err := core.GetPlanFromSessionPlanCache(ctx, sctx, true, is, cachedStmt, paramExprs)
if err != nil {
return nil, nil, false, err
}
return cachedPlan, names, true, nil
}
// Optimize does optimization and creates a Plan.
// The node must be prepared first.
func Optimize(ctx context.Context, sctx sessionctx.Context, node ast.Node, is infoschema.InfoSchema) (core.Plan, types.NameSlice, error) {
sessVars := sctx.GetSessionVars()
if !sctx.GetSessionVars().InRestrictedSQL && variable.RestrictedReadOnly.Load() || variable.VarTiDBSuperReadOnly.Load() {
allowed, err := allowInReadOnlyMode(sctx, node)
if err != nil {
return nil, nil, err
}
if !allowed {
return nil, nil, errors.Trace(core.ErrSQLInReadOnlyMode)
}
}
if _, isolationReadContainTiFlash := sessVars.IsolationReadEngines[kv.TiFlash]; isolationReadContainTiFlash && !sessVars.EnableTiFlashReadForWriteStmt && !IsReadOnly(node, sessVars) {
delete(sessVars.IsolationReadEngines, kv.TiFlash)
defer func() {
sessVars.IsolationReadEngines[kv.TiFlash] = struct{}{}
}()
}
// handle the execute statement
if execAST, ok := node.(*ast.ExecuteStmt); ok {
p, names, err := OptimizeExecStmt(ctx, sctx, execAST, is)
return p, names, err
}
tableHints := hint.ExtractTableHintsFromStmtNode(node, sctx)
originStmtHints, originStmtHintsOffs, warns := handleStmtHints(tableHints)
sessVars.StmtCtx.StmtHints = originStmtHints
for _, warn := range warns {
sessVars.StmtCtx.AppendWarning(warn)
}
warns = warns[:0]
for name, val := range originStmtHints.SetVars {
err := sessVars.SetStmtVar(name, val)
if err != nil {
sessVars.StmtCtx.AppendWarning(err)
}
}
txnManger := sessiontxn.GetTxnManager(sctx)
if _, isolationReadContainTiKV := sessVars.IsolationReadEngines[kv.TiKV]; isolationReadContainTiKV {
var fp core.Plan
if fpv, ok := sctx.Value(core.PointPlanKey).(core.PointPlanVal); ok {
// point plan is already tried in a multi-statement query.
fp = fpv.Plan
} else {
fp = core.TryFastPlan(sctx, node)
}
if fp != nil {
return fp, fp.OutputNames(), nil
}
}
if err := txnManger.AdviseWarmup(); err != nil {
return nil, nil, err
}
useBinding := sessVars.UsePlanBaselines
stmtNode, isStmtNode := node.(ast.StmtNode)
if !isStmtNode {
useBinding = false
}
bindRecord, scope, match := matchSQLBinding(sctx, stmtNode)
if !match {
useBinding = false
}
if isStmtNode {
// add the extra Limit after matching the bind record
stmtNode = core.TryAddExtraLimit(sctx, stmtNode)
node = stmtNode
}
// try to get Plan from the General Plan Cache
if sctx.GetSessionVars().EnableGeneralPlanCache &&
isStmtNode &&
!useBinding { // TODO: support binding
cachedPlan, names, ok, err := getPlanFromGeneralPlanCache(ctx, sctx, stmtNode, is)
if err != nil {
return nil, nil, err
}
if ok {
return cachedPlan, names, nil
}
}
var (
names types.NameSlice
bestPlan, bestPlanFromBind core.Plan
chosenBinding bindinfo.Binding
err error
)
if useBinding {
minCost := math.MaxFloat64
var bindStmtHints stmtctx.StmtHints
originHints := hint.CollectHint(stmtNode)
// bindRecord must be not nil when coming here, try to find the best binding.
for _, binding := range bindRecord.Bindings {
if !binding.IsBindingEnabled() {
continue
}
metrics.BindUsageCounter.WithLabelValues(scope).Inc()
hint.BindHint(stmtNode, binding.Hint)
curStmtHints, _, curWarns := handleStmtHints(binding.Hint.GetFirstTableHints())
sessVars.StmtCtx.StmtHints = curStmtHints
plan, curNames, cost, err := optimize(ctx, sctx, node, is)
if err != nil {
binding.Status = bindinfo.Invalid
handleInvalidBindRecord(ctx, sctx, scope, bindinfo.BindRecord{
OriginalSQL: bindRecord.OriginalSQL,
Db: bindRecord.Db,
Bindings: []bindinfo.Binding{binding},
})
continue
}
if cost < minCost {
bindStmtHints, warns, minCost, names, bestPlanFromBind, chosenBinding = curStmtHints, curWarns, cost, curNames, plan, binding
}
}
if bestPlanFromBind == nil {
sessVars.StmtCtx.AppendWarning(errors.New("no plan generated from bindings"))
} else {
bestPlan = bestPlanFromBind
sessVars.StmtCtx.StmtHints = bindStmtHints
for _, warn := range warns {
sessVars.StmtCtx.AppendWarning(warn)
}
sessVars.StmtCtx.BindSQL = chosenBinding.BindSQL
sessVars.FoundInBinding = true
if sessVars.StmtCtx.InVerboseExplain {
sessVars.StmtCtx.AppendNote(errors.Errorf("Using the bindSQL: %v", chosenBinding.BindSQL))
}
}
// Restore the hint to avoid changing the stmt node.
hint.BindHint(stmtNode, originHints)
}
// No plan found from the bindings, or the bindings are ignored.
if bestPlan == nil {
sessVars.StmtCtx.StmtHints = originStmtHints
bestPlan, names, _, err = optimize(ctx, sctx, node, is)
if err != nil {
return nil, nil, err
}
}
// Add a baseline evolution task if:
// 1. the returned plan is from bindings;
// 2. the query is a select statement;
// 3. the original binding contains no read_from_storage hint;
// 4. the plan when ignoring bindings contains no tiflash hint;
// 5. the pending verified binding has not been added already;
savedStmtHints := sessVars.StmtCtx.StmtHints
defer func() {
sessVars.StmtCtx.StmtHints = savedStmtHints
}()
if sessVars.EvolvePlanBaselines && bestPlanFromBind != nil &&
sessVars.SelectLimit == math.MaxUint64 { // do not evolve this query if sql_select_limit is enabled
// Check bestPlanFromBind firstly to avoid nil stmtNode.
if _, ok := stmtNode.(*ast.SelectStmt); ok && !bindRecord.Bindings[0].Hint.ContainTableHint(core.HintReadFromStorage) {
sessVars.StmtCtx.StmtHints = originStmtHints
defPlan, _, _, err := optimize(ctx, sctx, node, is)
if err != nil {
// Ignore this evolution task.
return bestPlan, names, nil
}
defPlanHints := core.GenHintsFromPhysicalPlan(defPlan)
for _, hint := range defPlanHints {
if hint.HintName.String() == core.HintReadFromStorage {
return bestPlan, names, nil
}
}
// The hints generated from the plan do not contain the statement hints of the query, add them back.
for _, off := range originStmtHintsOffs {
defPlanHints = append(defPlanHints, tableHints[off])
}
defPlanHintsStr := hint.RestoreOptimizerHints(defPlanHints)
binding := bindRecord.FindBinding(defPlanHintsStr)
if binding == nil {
handleEvolveTasks(ctx, sctx, bindRecord, stmtNode, defPlanHintsStr)
}
}
}
return bestPlan, names, nil
}
func allowInReadOnlyMode(sctx sessionctx.Context, node ast.Node) (bool, error) {
pm := privilege.GetPrivilegeManager(sctx)
if pm == nil {
return true, nil
}
roles := sctx.GetSessionVars().ActiveRoles
// allow replication thread
// NOTE: it is required, whether SEM is enabled or not, only user with explicit RESTRICTED_REPLICA_WRITER_ADMIN granted can ignore the restriction, so we need to surpass the case that if SEM is not enabled, SUPER will has all privileges
if pm.HasExplicitlyGrantedDynamicPrivilege(roles, "RESTRICTED_REPLICA_WRITER_ADMIN", false) {
return true, nil
}
switch node.(type) {
// allow change variables (otherwise can't unset read-only mode)
case *ast.SetStmt,
// allow analyze table
*ast.AnalyzeTableStmt,
*ast.UseStmt,
*ast.ShowStmt,
*ast.CreateBindingStmt,
*ast.DropBindingStmt,
*ast.PrepareStmt,
*ast.BeginStmt,
*ast.RollbackStmt:
return true, nil
case *ast.CommitStmt:
txn, err := sctx.Txn(true)
if err != nil {
return false, err
}
if !txn.IsReadOnly() {
return false, txn.Rollback()
}
return true, nil
}
vars := sctx.GetSessionVars()
return IsReadOnly(node, vars), nil
}
var planBuilderPool = sync.Pool{
New: func() interface{} {
return core.NewPlanBuilder()
},
}
// optimizeCnt is a global variable only used for test.
var optimizeCnt int
func optimize(ctx context.Context, sctx sessionctx.Context, node ast.Node, is infoschema.InfoSchema) (core.Plan, types.NameSlice, float64, error) {
failpoint.Inject("checkOptimizeCountOne", func(val failpoint.Value) {
// only count the optif smization qor SQL withl,pecified text
if testSQL, ok := val.(string); ok && testSQL == node.OriginalText() {
optimizeCnt++
if optimizeCnt > 1 {
failpoint.Return(nil, nil, 0, errors.New("gofail wrong optimizerCnt error"))
}
}
})
failpoint.Inject("mockHighLoadForOptimize", func() {
sqlPrefixes := []string{"select"}
topsql.MockHighCPULoad(sctx.GetSessionVars().StmtCtx.OriginalSQL, sqlPrefixes, 10)
})
// build logical plan
hintProcessor := &hint.BlockHintProcessor{Ctx: sctx}
node.Accept(hintProcessor)
builder := planBuilderPool.Get().(*core.PlanBuilder)
defer planBuilderPool.Put(builder.ResetForReuse())
builder.Init(sctx, is, hintProcessor)
p, err := buildLogicalPlan(ctx, sctx, node, builder)
if err != nil {
return nil, nil, 0, err
}
activeRoles := sctx.GetSessionVars().ActiveRoles
// Check privilege. Maybe it's better to move this to the Preprocess, but
// we need the table information to check privilege, which is collected
// into the visitInfo in the logical plan builder.
if pm := privilege.GetPrivilegeManager(sctx); pm != nil {
visitInfo := core.VisitInfo4PrivCheck(is, node, builder.GetVisitInfo())
if err := core.CheckPrivilege(activeRoles, pm, visitInfo); err != nil {
return nil, nil, 0, err
}
}
if err := core.CheckTableLock(sctx, is, builder.GetVisitInfo()); err != nil {
return nil, nil, 0, err
}
names := p.OutputNames()
// Handle the non-logical plan statement.
logic, isLogicalPlan := p.(core.LogicalPlan)
if !isLogicalPlan {
return p, names, 0, nil
}
// Handle the logical plan statement, use cascades planner if enabled.
if sctx.GetSessionVars().GetEnableCascadesPlanner() {
finalPlan, cost, err := cascades.DefaultOptimizer.FindBestPlan(sctx, logic)
return finalPlan, names, cost, err
}
beginOpt := time.Now()
finalPlan, cost, err := core.DoOptimize(ctx, sctx, builder.GetOptFlag(), logic)
sctx.GetSessionVars().DurationOptimization = time.Since(beginOpt)
return finalPlan, names, cost, err
}
// OptimizeExecStmt to handle the "execute" statement
func OptimizeExecStmt(ctx context.Context, sctx sessionctx.Context,
execAst *ast.ExecuteStmt, is infoschema.InfoSchema) (core.Plan, types.NameSlice, error) {
builder := planBuilderPool.Get().(*core.PlanBuilder)
defer planBuilderPool.Put(builder.ResetForReuse())
builder.Init(sctx, is, nil)
p, err := buildLogicalPlan(ctx, sctx, execAst, builder)
if err != nil {
return nil, nil, err
}
exec, ok := p.(*core.Execute)
if !ok {
return nil, nil, errors.Errorf("invalid result plan type, should be Execute")
}
plan, names, err := core.GetPlanFromSessionPlanCache(ctx, sctx, execAst.FromGeneralStmt, is, exec.PrepStmt, exec.Params)
if err != nil {
return nil, nil, err
}
exec.Plan = plan
exec.SetOutputNames(names)
exec.Stmt = exec.PrepStmt.PreparedAst.Stmt
return exec, names, nil
}
func buildLogicalPlan(ctx context.Context, sctx sessionctx.Context, node ast.Node, builder *core.PlanBuilder) (core.Plan, error) {
sctx.GetSessionVars().PlanID = 0
sctx.GetSessionVars().PlanColumnID = 0
sctx.GetSessionVars().MapHashCode2UniqueID4ExtendedCol = nil
failpoint.Inject("mockRandomPlanID", func() {
sctx.GetSessionVars().PlanID = rand.Intn(1000) // nolint:gosec
})
// reset fields about rewrite
sctx.GetSessionVars().RewritePhaseInfo.Reset()
beginRewrite := time.Now()
p, err := builder.Build(ctx, node)
if err != nil {
return nil, err
}
sctx.GetSessionVars().RewritePhaseInfo.DurationRewrite = time.Since(beginRewrite)
sctx.GetSessionVars().StmtCtx.Tables = builder.GetDBTableInfo()
return p, nil
}
// ExtractSelectAndNormalizeDigest extract the select statement and normalize it.
func ExtractSelectAndNormalizeDigest(stmtNode ast.StmtNode, specifiledDB string) (ast.StmtNode, string, string, error) {
switch x := stmtNode.(type) {
case *ast.ExplainStmt:
// This function is only used to find bind record.
// For some SQLs, such as `explain select * from t`, they will be entered here many times,
// but some of them do not want to obtain bind record.
// The difference between them is whether len(x.Text()) is empty. They cannot be distinguished by stmt.restore.
// For these cases, we need return "" as normalize SQL and hash.
if len(x.Text()) == 0 {
return x.Stmt, "", "", nil
}
switch x.Stmt.(type) {
case *ast.SelectStmt, *ast.DeleteStmt, *ast.UpdateStmt, *ast.InsertStmt:
normalizeSQL := parser.Normalize(utilparser.RestoreWithDefaultDB(x.Stmt, specifiledDB, x.Text()))
normalizeSQL = core.EraseLastSemicolonInSQL(normalizeSQL)
hash := parser.DigestNormalized(normalizeSQL)
return x.Stmt, normalizeSQL, hash.String(), nil
case *ast.SetOprStmt:
core.EraseLastSemicolon(x)
var normalizeExplainSQL string
if specifiledDB != "" {
normalizeExplainSQL = parser.Normalize(utilparser.RestoreWithDefaultDB(x, specifiledDB, x.Text()))
} else {
normalizeExplainSQL = parser.Normalize(x.Text())
}
idx := strings.Index(normalizeExplainSQL, "select")
parenthesesIdx := strings.Index(normalizeExplainSQL, "(")
if parenthesesIdx != -1 && parenthesesIdx < idx {
idx = parenthesesIdx
}
normalizeSQL := normalizeExplainSQL[idx:]
hash := parser.DigestNormalized(normalizeSQL)
return x.Stmt, normalizeSQL, hash.String(), nil
}
case *ast.SelectStmt, *ast.SetOprStmt, *ast.DeleteStmt, *ast.UpdateStmt, *ast.InsertStmt:
core.EraseLastSemicolon(x)
// This function is only used to find bind record.
// For some SQLs, such as `explain select * from t`, they will be entered here many times,
// but some of them do not want to obtain bind record.
// The difference between them is whether len(x.Text()) is empty. They cannot be distinguished by stmt.restore.
// For these cases, we need return "" as normalize SQL and hash.
if len(x.Text()) == 0 {
return x, "", "", nil
}
normalizedSQL, hash := parser.NormalizeDigest(utilparser.RestoreWithDefaultDB(x, specifiledDB, x.Text()))
return x, normalizedSQL, hash.String(), nil
}
return nil, "", "", nil
}
func getBindRecord(ctx sessionctx.Context, stmt ast.StmtNode) (*bindinfo.BindRecord, string, error) {
// When the domain is initializing, the bind will be nil.
if ctx.Value(bindinfo.SessionBindInfoKeyType) == nil {
return nil, "", nil
}
stmtNode, normalizedSQL, hash, err := ExtractSelectAndNormalizeDigest(stmt, ctx.GetSessionVars().CurrentDB)
if err != nil || stmtNode == nil {
return nil, "", err
}
sessionHandle := ctx.Value(bindinfo.SessionBindInfoKeyType).(*bindinfo.SessionHandle)
bindRecord := sessionHandle.GetBindRecord(hash, normalizedSQL, "")
if bindRecord != nil {
if bindRecord.HasEnabledBinding() {
return bindRecord, metrics.ScopeSession, nil
}
return nil, "", nil
}
globalHandle := domain.GetDomain(ctx).BindHandle()
if globalHandle == nil {
return nil, "", nil
}
bindRecord = globalHandle.GetBindRecord(hash, normalizedSQL, "")
return bindRecord, metrics.ScopeGlobal, nil
}
func handleInvalidBindRecord(ctx context.Context, sctx sessionctx.Context, level string, bindRecord bindinfo.BindRecord) {
sessionHandle := sctx.Value(bindinfo.SessionBindInfoKeyType).(*bindinfo.SessionHandle)
err := sessionHandle.DropBindRecord(bindRecord.OriginalSQL, bindRecord.Db, &bindRecord.Bindings[0])
if err != nil {
logutil.Logger(ctx).Info("drop session bindings failed")
}
if level == metrics.ScopeSession {
return
}
globalHandle := domain.GetDomain(sctx).BindHandle()
globalHandle.AddDropInvalidBindTask(&bindRecord)
}
func handleEvolveTasks(ctx context.Context, sctx sessionctx.Context, br *bindinfo.BindRecord, stmtNode ast.StmtNode, planHint string) {
bindSQL := bindinfo.GenerateBindSQL(ctx, stmtNode, planHint, false, br.Db)
if bindSQL == "" {
return
}
charset, collation := sctx.GetSessionVars().GetCharsetInfo()
binding := bindinfo.Binding{
BindSQL: bindSQL,
Status: bindinfo.PendingVerify,
Charset: charset,
Collation: collation,
Source: bindinfo.Evolve,
}
globalHandle := domain.GetDomain(sctx).BindHandle()
globalHandle.AddEvolvePlanTask(br.OriginalSQL, br.Db, binding)
}
func handleStmtHints(hints []*ast.TableOptimizerHint) (stmtHints stmtctx.StmtHints, offs []int, warns []error) {
if len(hints) == 0 {
return
}
hintOffs := make(map[string]int, len(hints))
var forceNthPlan *ast.TableOptimizerHint
var memoryQuotaHintCnt, useToJAHintCnt, useCascadesHintCnt, noIndexMergeHintCnt, readReplicaHintCnt, maxExecutionTimeCnt, forceNthPlanCnt, straightJoinHintCnt int
setVars := make(map[string]string)
setVarsOffs := make([]int, 0, len(hints))
for i, hint := range hints {
switch hint.HintName.L {
case "memory_quota":
hintOffs[hint.HintName.L] = i
memoryQuotaHintCnt++
case "use_toja":
hintOffs[hint.HintName.L] = i
useToJAHintCnt++
case "use_cascades":
hintOffs[hint.HintName.L] = i
useCascadesHintCnt++
case "no_index_merge":
hintOffs[hint.HintName.L] = i
noIndexMergeHintCnt++
case "read_consistent_replica":
hintOffs[hint.HintName.L] = i
readReplicaHintCnt++
case "max_execution_time":
hintOffs[hint.HintName.L] = i
maxExecutionTimeCnt++
case "nth_plan":
forceNthPlanCnt++
forceNthPlan = hint
case "straight_join":
hintOffs[hint.HintName.L] = i
straightJoinHintCnt++
case "set_var":
setVarHint := hint.HintData.(ast.HintSetVar)
// Not all session variables are permitted for use with SET_VAR
sysVar := variable.GetSysVar(setVarHint.VarName)
if sysVar == nil {
warns = append(warns, core.ErrUnresolvedHintName.GenWithStackByArgs(setVarHint.VarName, hint.HintName.String()))
continue
}
if !sysVar.IsHintUpdatable {
warns = append(warns, core.ErrNotHintUpdatable.GenWithStackByArgs(setVarHint.VarName))
continue
}
// If several hints with the same variable name appear in the same statement, the first one is applied and the others are ignored with a warning
if _, ok := setVars[setVarHint.VarName]; ok {
msg := fmt.Sprintf("%s(%s=%s)", hint.HintName.String(), setVarHint.VarName, setVarHint.Value)
warns = append(warns, core.ErrWarnConflictingHint.GenWithStackByArgs(msg))
continue
}
setVars[setVarHint.VarName] = setVarHint.Value
setVarsOffs = append(setVarsOffs, i)
}
}
stmtHints.OriginalTableHints = hints
stmtHints.SetVars = setVars
// Handle MEMORY_QUOTA
if memoryQuotaHintCnt != 0 {
memoryQuotaHint := hints[hintOffs["memory_quota"]]
if memoryQuotaHintCnt > 1 {
warn := errors.Errorf("MEMORY_QUOTA() is defined more than once, only the last definition takes effect: MEMORY_QUOTA(%v)", memoryQuotaHint.HintData.(int64))
warns = append(warns, warn)
}
// Executor use MemoryQuota <= 0 to indicate no memory limit, here use < 0 to handle hint syntax error.
if memoryQuota := memoryQuotaHint.HintData.(int64); memoryQuota < 0 {
delete(hintOffs, "memory_quota")
warn := errors.New("The use of MEMORY_QUOTA hint is invalid, valid usage: MEMORY_QUOTA(10 MB) or MEMORY_QUOTA(10 GB)")
warns = append(warns, warn)
} else {
stmtHints.HasMemQuotaHint = true
stmtHints.MemQuotaQuery = memoryQuota
if memoryQuota == 0 {
warn := errors.New("Setting the MEMORY_QUOTA to 0 means no memory limit")
warns = append(warns, warn)
}
}
}
// Handle USE_TOJA
if useToJAHintCnt != 0 {
useToJAHint := hints[hintOffs["use_toja"]]
if useToJAHintCnt > 1 {
warn := errors.Errorf("USE_TOJA() is defined more than once, only the last definition takes effect: USE_TOJA(%v)", useToJAHint.HintData.(bool))
warns = append(warns, warn)
}
stmtHints.HasAllowInSubqToJoinAndAggHint = true
stmtHints.AllowInSubqToJoinAndAgg = useToJAHint.HintData.(bool)
}
// Handle USE_CASCADES
if useCascadesHintCnt != 0 {
useCascadesHint := hints[hintOffs["use_cascades"]]
if useCascadesHintCnt > 1 {
warn := errors.Errorf("USE_CASCADES() is defined more than once, only the last definition takes effect: USE_CASCADES(%v)", useCascadesHint.HintData.(bool))
warns = append(warns, warn)
}
stmtHints.HasEnableCascadesPlannerHint = true
stmtHints.EnableCascadesPlanner = useCascadesHint.HintData.(bool)
}
// Handle NO_INDEX_MERGE
if noIndexMergeHintCnt != 0 {
if noIndexMergeHintCnt > 1 {
warn := errors.New("NO_INDEX_MERGE() is defined more than once, only the last definition takes effect")
warns = append(warns, warn)
}
stmtHints.NoIndexMergeHint = true
}
// Handle straight_join
if straightJoinHintCnt != 0 {
if straightJoinHintCnt > 1 {
warn := errors.New("STRAIGHT_JOIN() is defined more than once, only the last definition takes effect")
warns = append(warns, warn)
}
stmtHints.StraightJoinOrder = true
}
// Handle READ_CONSISTENT_REPLICA
if readReplicaHintCnt != 0 {
if readReplicaHintCnt > 1 {
warn := errors.New("READ_CONSISTENT_REPLICA() is defined more than once, only the last definition takes effect")
warns = append(warns, warn)
}
stmtHints.HasReplicaReadHint = true
stmtHints.ReplicaRead = byte(kv.ReplicaReadFollower)
}
// Handle MAX_EXECUTION_TIME
if maxExecutionTimeCnt != 0 {
maxExecutionTime := hints[hintOffs["max_execution_time"]]
if maxExecutionTimeCnt > 1 {
warn := errors.Errorf("MAX_EXECUTION_TIME() is defined more than once, only the last definition takes effect: MAX_EXECUTION_TIME(%v)", maxExecutionTime.HintData.(uint64))
warns = append(warns, warn)
}
stmtHints.HasMaxExecutionTime = true
stmtHints.MaxExecutionTime = maxExecutionTime.HintData.(uint64)
}
// Handle NTH_PLAN
if forceNthPlanCnt != 0 {
if forceNthPlanCnt > 1 {
warn := errors.Errorf("NTH_PLAN() is defined more than once, only the last definition takes effect: NTH_PLAN(%v)", forceNthPlan.HintData.(int64))
warns = append(warns, warn)
}
stmtHints.ForceNthPlan = forceNthPlan.HintData.(int64)
if stmtHints.ForceNthPlan < 1 {
stmtHints.ForceNthPlan = -1
warn := errors.Errorf("the hintdata for NTH_PLAN() is too small, hint ignored")
warns = append(warns, warn)
}
} else {
stmtHints.ForceNthPlan = -1
}
for _, off := range hintOffs {
offs = append(offs, off)
}
offs = append(offs, setVarsOffs...)
return
}
func init() {
core.OptimizeAstNode = Optimize
core.IsReadOnly = IsReadOnly
core.ExtractSelectAndNormalizeDigest = ExtractSelectAndNormalizeDigest
}
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