schemas

type Allocator interface {
	// Alloc allocs the next autoID for table with tableID.
	// It gets a batch of autoIDs at a time. So it does not need to access storage for each call.
	Alloc(tableID int64) (int64, error)
	// Rebase rebases the autoID base for table with tableID and the new base value.
	// If allocIDs is true, it will allocate some IDs and save to the cache.
	// If allocIDs is false, it will not allocate IDs.
	Rebase(tableID, newBase int64, allocIDs bool) error
	// NextGlobalAutoID returns the next global autoID.
	NextGlobalAutoID(tableID int64) (int64, error)
}

type ColDesc struct {
	Field        string
	Type         string
	Collation    string
	Null         string
	Key          string
	DefaultValue interface{}
	Extra        string
	Privileges   string
	Comment      string
}

type Column struct {
	*model.ColumnInfo
	// If this column is a generated column, the expression will be stored here.
	GeneratedExpr ast.ExprNode
}

type Database interface {
	Name() string

	GetTable(name string) (Table, error)

	ListTables() []Table

	DropTable(name string) error

	ListTableName() []string
}

type Index interface {
	// Meta returns IndexInfo.
	Meta() *model.IndexInfo
	// Create supports insert into statement.
	//Create(ctx context.Context, rm kv.RetrieverMutator,
	//	indexedValues []types.Datum, h int64) (int64, error)
	//// Delete supports delete from statement.
	//Delete(m kv.Mutator, indexedValues []types.Datum, h int64) error
	//// Drop supports drop table, drop index statements.
	//Drop(rm kv.RetrieverMutator) error
	//// Exist supports check index exists or not.
	//Exist(rm kv.RetrieverMutator, indexedValues []types.Datum, h int64) (bool, int64, error)
	//// GenIndexKey generates an index key.
	//GenIndexKey(indexedValues []types.Datum, h int64) (key []byte, distinct bool, err error)
	//// Seek supports where clause.
	//Seek(r kv.Retriever, indexedValues []types.Datum) (iter IndexIterator, hit bool, err error)
	//// SeekFirst supports aggregate min and ascend order by.
	//SeekFirst(r kv.Retriever) (iter IndexIterator, err error)
	// FetchValues fetched index column values in a row.
	FetchValues(row []types.Datum) (columns []types.Datum, err error)
}

type IndexIterator interface {
	Next() (k []types.Datum, h int64, err error)
	Close()
}

type InfoSchema interface {
	SchemaByName(schema model.CIStr) (*model.DBInfo, bool)

	SchemaExists(schema model.CIStr) bool

	TableByName(schema, table model.CIStr) (Table, error)

	TableExists(schema, table model.CIStr) bool

	AllSchemaNames() []string

	AllSchemas() []*model.DBInfo

	Clone() (result []*model.DBInfo)

	SchemaTables(schema model.CIStr) []Table

	//获取数据库对象
	GetSchemaByName(schemaName string) (Database, error)

	//判断数据库是否存在
	GetSchemaExist(schemaName string) bool

	GetTableByName(schema string, tableName string) (Table, error)

	GetTableExist(schemaName string, tableName string) bool

	SchemaByID(id int64) (*model.DBInfo, bool)

	TableByID(id int64) (Table, bool)

	AllocByID(id int64) (Allocator, bool)

	SchemaMetaVersion() int64
}

type PerformanceSchemas interface {
}

type Table interface {

	// Meta returns TableInfo.
	Meta() *model.TableInfo

	TableName() string

	TableId() uint64

	SpaceId() uint32

	ColNums() int

	RowIter() (basic.RowIterator, error)

	GetBtree(indexName string) basic.Tree

	CheckFieldName(fieldName string) bool

	GetAllColumns() []*tuple.FormColumnsWrapper

	GetTableTupleMeta() tuple.TableTuple

	//获取索引
	GetIndex(indexName string) basic.Index

	// Cols returns the columns of the table which is used in select.
	Cols() []*Column

	// WritableCols returns columns of the table in writable states.
	// Writable states includes Public, WriteOnly, WriteOnlyReorganization.
	WritableCols() []*Column
}

type TupleLRUCache interface {

	//lru 中设置spaceId,pageNo
	Set(databaseName string, tableName string, table Table) error

	Get(databaseName string, tableName string) (Table, error)

	Remove(databaseName string, tableName string) bool

	// Has returns true if the key exists in the cache.
	Has(databaseName string, tableName string) bool

	Len() uint32
}