Semijoin_mat_optimize Struct Reference

Semijoin_mat_optimize collects data used when calculating the cost of executing a semijoin operation using a materialization strategy. More...

#include <nested_join.h>

Public Attributes
POSITION *	positions {nullptr}
	Optimal join order calculated for inner tables of this semijoin op. More...
bool	lookup_allowed {false}
	True if data types allow the MaterializeLookup semijoin strategy. More...
bool	scan_allowed {false}
	True if data types allow the MaterializeScan semijoin strategy. More...
double	expected_rowcount {0.0}
	Expected number of rows in the materialized table. More...
Cost_estimate	materialization_cost
	Materialization cost - execute sub-join and write rows to temp.table. More...
Cost_estimate	lookup_cost
	Cost to make one lookup in the temptable. More...
Cost_estimate	scan_cost
	Cost of scanning the materialized table. More...
Item_field **	mat_fields {nullptr}
	Array of pointers to fields in the materialized table. More...

Detailed Description

Semijoin_mat_optimize collects data used when calculating the cost of executing a semijoin operation using a materialization strategy.

It is used during optimization phase only.

Member Data Documentation

expected_rowcount

double Semijoin_mat_optimize::expected_rowcount {0.0}

Expected number of rows in the materialized table.

lookup_allowed

bool Semijoin_mat_optimize::lookup_allowed {false}

True if data types allow the MaterializeLookup semijoin strategy.

lookup_cost

Cost_estimate Semijoin_mat_optimize::lookup_cost

Cost to make one lookup in the temptable.

mat_fields

Item_field** Semijoin_mat_optimize::mat_fields {nullptr}

Array of pointers to fields in the materialized table.

materialization_cost

Cost_estimate Semijoin_mat_optimize::materialization_cost

Materialization cost - execute sub-join and write rows to temp.table.

positions

POSITION* Semijoin_mat_optimize::positions {nullptr}

Optimal join order calculated for inner tables of this semijoin op.

scan_allowed

bool Semijoin_mat_optimize::scan_allowed {false}

True if data types allow the MaterializeScan semijoin strategy.

scan_cost

Cost_estimate Semijoin_mat_optimize::scan_cost

Cost of scanning the materialized table.

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The documentation for this struct was generated from the following file:

• sql/nested_join.h