IndexSkipScanCost Class Reference

Manage cost-related info and cost calculation functions for index skip scans. More...

#include <index_skip_scan_plan.h>

Classes
struct	IndexSkipScanCardinality

Public Member Functions
	IndexSkipScanCost (TABLE *tab, uint cur_key, uint keyparts, ha_rows prefix_records, Item *where, Opt_trace_object *trace_idx)
Cost_estimate	GetCost () const
	DESCRIPTION This method computes the access cost of an INDEX_SKIP_SCAN access path and the number of rows returned for the old optimizer. More...
double	GetCostForHypergraph () const
	DESCRIPTION This method computes the access cost of an INDEX_SKIP_SCAN access path and the number of rows returned in hypergraph. More...
ha_rows	GetNumRecords () const

Private Member Functions
void	CalcCardinality ()
	DESCRIPTION This method computes the parameters used to calculate the access cost of an INDEX_SKIP_SCAN access path and the number of rows returned. More...

Private Attributes
TABLE *	m_table
uint	m_key
uint	m_distinct_key_parts
ha_rows	m_quick_prefix_records
Item *	m_where_cond
Opt_trace_object *	m_trace
struct IndexSkipScanCost::IndexSkipScanCardinality	m_cardinality

Detailed Description

Manage cost-related info and cost calculation functions for index skip scans.

Constructor & Destructor Documentation

IndexSkipScanCost()

IndexSkipScanCost::IndexSkipScanCost ( TABLE *  tab, uint  cur_key, uint  keyparts, ha_rows  prefix_records, Item *  where, Opt_trace_object *  trace_idx  )

inline

Member Function Documentation

CalcCardinality()

void IndexSkipScanCost::CalcCardinality ( )

private

DESCRIPTION This method computes the parameters used to calculate the access cost of an INDEX_SKIP_SCAN access path and the number of rows returned.

NOTES To estimate the size of the groups to read, index statistics from rec_per_key is used. Each equality range decreases number of the groups to read. The total number of processed records from all the groups will be quick_prefix_records if there are equality ranges else it will be the entire table. Number of distinct group is calculated by dividing the number of processed record by the number keys in a group.

Number of processed records is calculated using following formula:

records = number_of_distinct_groups * records_per_group * filtering_effect

where filtering_effect is filtering effect of the range condition.

GetCost()

Cost_estimate IndexSkipScanCost::GetCost

(

)

const

DESCRIPTION This method computes the access cost of an INDEX_SKIP_SCAN access path and the number of rows returned for the old optimizer.

RETURN Cost estimate

GetCostForHypergraph()

double IndexSkipScanCost::GetCostForHypergraph

(

)

const

DESCRIPTION This method computes the access cost of an INDEX_SKIP_SCAN access path and the number of rows returned in hypergraph.

RETURN Hypergraph cost value.

GetNumRecords()

ha_rows IndexSkipScanCost::GetNumRecords ( ) const

inline

Member Data Documentation

m_cardinality

struct IndexSkipScanCost::IndexSkipScanCardinality IndexSkipScanCost::m_cardinality

private

m_distinct_key_parts

uint IndexSkipScanCost::m_distinct_key_parts

private

m_key

uint IndexSkipScanCost::m_key

private

m_quick_prefix_records

ha_rows IndexSkipScanCost::m_quick_prefix_records

private

m_table

TABLE* IndexSkipScanCost::m_table

private

m_trace

Opt_trace_object* IndexSkipScanCost::m_trace

private

m_where_cond

Item* IndexSkipScanCost::m_where_cond

private

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The documentation for this class was generated from the following files:

• sql/range_optimizer/index_skip_scan_plan.h
• sql/range_optimizer/index_skip_scan_plan.cc