bindinfo

type Binding struct {
	OriginalSQL string
	Db          string
	BindSQL     string
	// Status represents the status of the binding. It can only be one of the following values:
	// 1. deleted: Bindings is deleted, can not be used anymore.
	// 2. enabled, using: Binding is in the normal active mode.
	Status     string
	CreateTime types.Time
	UpdateTime types.Time
	Source     string
	Charset    string
	Collation  string
	// Hint is the parsed hints, it is used to bind hints to stmt node.
	Hint *hint.HintsSet `json:"-"`
	// ID is the string form of Hint. It would be non-empty only when the status is `Using` or `PendingVerify`.
	ID         string `json:"-"`
	SQLDigest  string
	PlanDigest string

	// TableNames records all schema and table names in this binding statement, which are used for cross-db matching.
	TableNames []*ast.TableName `json:"-"`

	// UsageInfo is to track the usage information `last_used_time` of this binding
	// and it will be updated when this binding is used.
	UsageInfo bindingInfoUsageInfo
}

type BindingCache interface {
	// MatchingBinding supports cross-db matching on bindings.
	MatchingBinding(sctx sessionctx.Context, noDBDigest string, tableNames []*ast.TableName) (binding *Binding, isMatched bool)
	// GetBinding gets the binding for the specified sqlDigest.
	GetBinding(sqlDigest string) *Binding
	// GetAllBindings gets all the bindings in the cache.
	GetAllBindings() []*Binding
	// SetBinding sets the binding for the specified sqlDigest.
	SetBinding(sqlDigest string, binding *Binding) (err error)
	// RemoveBinding removes the binding for the specified sqlDigest.
	RemoveBinding(sqlDigest string)
	// SetMemCapacity sets the memory capacity for the cache.
	SetMemCapacity(capacity int64)
	// GetMemUsage gets the memory usage of the cache.
	GetMemUsage() int64
	// GetMemCapacity gets the memory capacity of the cache.
	GetMemCapacity() int64
	// Size returns the number of items in the cache.
	Size() int
	// Close closes the cache.
	Close()
}

type BindingCacheUpdater interface {
	BindingCache

	// LoadFromStorageToCache loads global bindings from storage to the memory cache.
	LoadFromStorageToCache(fullLoad bool) (err error)

	// UpdateBindingUsageInfoToStorage is to update the binding usage info into storage
	UpdateBindingUsageInfoToStorage() error

	// LastUpdateTime returns the last update time.
	LastUpdateTime() types.Time
}

type BindingHandle interface {
	BindingCacheUpdater

	BindingOperator

	BindingPlanEvolution

	variable.Statistics
}

type BindingMatchInfo struct {
	NoDBDigest string
	TableNames []*ast.TableName
}

type BindingOperator interface {
	// CreateBinding creates a Bindings to the storage and the cache.
	// It replaces all the exists bindings for the same normalized SQL.
	CreateBinding(sctx sessionctx.Context, bindings []*Binding) (err error)

	// DropBinding drop Bindings to the storage and Bindings int the cache.
	DropBinding(sqlDigests []string) (deletedRows uint64, err error)

	// SetBindingStatus set a Bindings's status to the storage and bind cache.
	SetBindingStatus(newStatus, sqlDigest string) (ok bool, err error)

	// GCBinding physically removes the deleted bind records in mysql.bind_info.
	GCBinding() (err error)
}

type BindingPlanEvolution interface {

	// ExplorePlansForSQL explores plans for this SQL.
	ExplorePlansForSQL(stmtSCtx base.PlanContext, sqlOrDigest string, analyze bool) ([]*BindingPlanInfo, error)
}

type BindingPlanInfo struct {
	*Binding

	// Info from StmtStats
	Plan                 string
	AvgLatency           float64
	ExecTimes            int64
	AvgScanRows          float64
	AvgReturnedRows      float64
	LatencyPerReturnRow  float64
	ScanRowsPerReturnRow float64

	// Recommendation
	Recommend string
	Reason    string
}

type PlanGenerator interface {
	Generate(defaultSchema, sql, charset, collation string) (plans []*BindingPlanInfo, err error)
}

type PlanPerfPredictor interface {
	PerfPredicate(plans []*BindingPlanInfo) (scores []float64, explanations []string, err error)
}

type SessionBindingHandle interface {
	// CreateSessionBinding creates a binding to the cache.
	CreateSessionBinding(sctx sessionctx.Context, bindings []*Binding) (err error)

	// DropSessionBinding drops a binding by the sql digest.
	DropSessionBinding(sqlDigests []string) error

	// MatchSessionBinding returns the matched binding for this statement.
	MatchSessionBinding(sctx sessionctx.Context, noDBDigest string, tableNames []*ast.TableName) (matchedBinding *Binding, isMatched bool)

	// GetAllSessionBindings return all bindings.
	GetAllSessionBindings() (bindings []*Binding)

	// Close closes the SessionBindingHandle.
	Close()

	sessionctx.SessionStatesHandler
}