Documentation
¶
Index ¶
- Constants
- type Concurrency
- type PreparedParams
- type SessionVars
- func (s *SessionVars) AllocPlanColumnID() int64
- func (s *SessionVars) GetCharsetInfo() (charset, collation string)
- func (s *SessionVars) GetDescScanFactor(tbl *model.TableInfo) float64
- func (s *SessionVars) GetNetworkFactor(tbl *model.TableInfo) float64
- func (s *SessionVars) GetScanFactor(tbl *model.TableInfo) float64
- func (s *SessionVars) GetSeekFactor(tbl *model.TableInfo) float64
- func (s *SessionVars) Location() *time.Location
Constants ¶
const ( DefOptCPUFactor = 3.0 DefOptNetworkFactor = 1.0 DefOptScanFactor = 1.5 DefOptDescScanFactor = 3.0 DefOptSeekFactor = 20.0 DefOptMemoryFactor = 0.001 DefOptDiskFactor = 1.5 DefOptConcurrencyFactor = 3.0 DefTiDBProjectionConcurrency = ConcurrencyUnset DefTiDBHashAggPartialConcurrency = ConcurrencyUnset DefTiDBHashAggFinalConcurrency = ConcurrencyUnset DefEnableVectorizedExpression = true DefExecutorConcurrency = 5 )
const ConcurrencyUnset = -1
ConcurrencyUnset means the value the of the concurrency related variable is unset.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Concurrency ¶
type Concurrency struct {
// ExecutorConcurrency is the number of concurrent worker for all executors.
ExecutorConcurrency int
// contains filtered or unexported fields
}
Concurrency defines concurrency values.
func (*Concurrency) HashAggFinalConcurrency ¶
func (c *Concurrency) HashAggFinalConcurrency() int
HashAggFinalConcurrency return the number of concurrent hash aggregation final worker.
func (*Concurrency) HashAggPartialConcurrency ¶
func (c *Concurrency) HashAggPartialConcurrency() int
HashAggPartialConcurrency return the number of concurrent hash aggregation partial worker.
func (*Concurrency) ProjectionConcurrency ¶
func (c *Concurrency) ProjectionConcurrency() int
ProjectionConcurrency return the number of concurrent projection worker.
type PreparedParams ¶
PreparedParams contains the parameters of the current prepared statement when executing it.
func (PreparedParams) String ¶
func (pps PreparedParams) String() string
type SessionVars ¶
type SessionVars struct {
Concurrency
// PreparedParams params for prepared statements
PreparedParams PreparedParams
// Status stands for the session status. e.g. in transaction or not, auto commit is on or off, and so on.
Status uint16
// PlanID is the unique id of logical and physical plan.
PlanID int
// PlanColumnID is the unique id for column when building plan.
PlanColumnID int64
// CurrentDB is the default database of this session.
CurrentDB string
// StmtCtx holds variables for current executing statement.
StmtCtx *stmtctx.StatementContext
// CPUFactor is the CPU cost of processing one expression for one row.
CPUFactor float64
// MemoryFactor is the memory cost of storing one tuple.
MemoryFactor float64
// DiskFactor is the IO cost of reading/writing one byte to temporary disk.
DiskFactor float64
// ConcurrencyFactor is the CPU cost of additional one goroutine.
ConcurrencyFactor float64
// Per-connection time zones. Each client that connects has its own time zone setting, given by the session time_zone variable.
// See https://dev.mysql.com/doc/refman/5.7/en/time-zone-support.html
TimeZone *time.Location
SQLMode mysql.SQLMode
// EnableVectorizedExpression enables the vectorized expression evaluation.
EnableVectorizedExpression bool
MaxAllowedPacket uint64
DefaultWeekFormat string
// contains filtered or unexported fields
}
SessionVars is to handle user-defined or global variables in the current session.
func NewSessionVars ¶
func NewSessionVars() *SessionVars
NewSessionVars creates a session vars object.
func (*SessionVars) AllocPlanColumnID ¶
func (s *SessionVars) AllocPlanColumnID() int64
AllocPlanColumnID allocates column id for plan.
func (*SessionVars) GetCharsetInfo ¶
func (s *SessionVars) GetCharsetInfo() (charset, collation string)
GetCharsetInfo gets charset and collation for current context. What character set should the server translate a statement to after receiving it? For this, the server uses the character_set_connection and collation_connection system variables. It converts statements sent by the client from character_set_client to character_set_connection (except for string literals that have an introducer such as _latin1 or _utf8). collation_connection is important for comparisons of literal strings. For comparisons of strings with column values, collation_connection does not matter because columns have their own collation, which has a higher collation precedence. See https://dev.mysql.com/doc/refman/5.7/en/charset-connection.html
func (*SessionVars) GetDescScanFactor ¶
func (s *SessionVars) GetDescScanFactor(tbl *model.TableInfo) float64
GetDescScanFactor returns the session variable descScanFactor returns 0 when tbl is a temporary table.
func (*SessionVars) GetNetworkFactor ¶
func (s *SessionVars) GetNetworkFactor(tbl *model.TableInfo) float64
GetNetworkFactor returns the session variable networkFactor returns 0 when tbl is a temporary table.
func (*SessionVars) GetScanFactor ¶
func (s *SessionVars) GetScanFactor(tbl *model.TableInfo) float64
GetScanFactor returns the session variable scanFactor returns 0 when tbl is a temporary table.
func (*SessionVars) GetSeekFactor ¶
func (s *SessionVars) GetSeekFactor(tbl *model.TableInfo) float64
GetSeekFactor returns the session variable seekFactor returns 0 when tbl is a temporary table.
func (*SessionVars) Location ¶
func (s *SessionVars) Location() *time.Location
Location returns the value of time_zone session variable. If it is nil, then return time.Local.
Source Files