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Code Activity

Split cost calculations into fetch and total

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This patch causes no changes in costs or result files.

Changes:
- Store row compare cost separately in Cost_estimate::comp_cost
- Store cost of fetching rows separately in OPT_RANGE
- Use range->fetch_cost instead of adjust_quick_cost(total_cost)

This was done to simplify cost calculation in sql_select.cc:
- We can use range->fetch_cost directly without having to call
  adjust_quick_cost(). adjust_quick_cost() is now removed.

Other things:
- Removed some not used functions in Cost_estimate
This commit is contained in:
Monty
2021-10-21 19:40:58 +03:00
committed by Sergei Petrunia
parent 766bae2b31
commit e6205c966d
5 changed files with 42 additions and 42 deletions
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36
sql/handler.h
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@@ -2780,6 +2780,7 @@ public:
double cpu_cost; /* total cost of operations in CPU */
double idx_cpu_cost; /* cost of operations in CPU for index */
double import_cost; /* cost of remote operations */
double comp_cost; /* Cost of comparing found rows with WHERE clause */
double mem_cost; /* cost of used memory */
static constexpr double IO_COEFF= 1;
@@ -2793,6 +2794,15 @@ public:
}
double total_cost() const
{
return IO_COEFF*io_count*avg_io_cost +
IO_COEFF*idx_io_count*idx_avg_io_cost +
CPU_COEFF*(cpu_cost + idx_cpu_cost + comp_cost) +
MEM_COEFF*mem_cost + IMPORT_COEFF*import_cost;
}
/* Cost of fetching a row */
double fetch_cost() const
{
return IO_COEFF*io_count*avg_io_cost +
IO_COEFF*idx_io_count*idx_avg_io_cost +
@@ -2800,6 +2810,16 @@ public:
MEM_COEFF*mem_cost + IMPORT_COEFF*import_cost;
}
/*
Cost of comparing the row with the WHERE clause
Note that fetch_cost() + compare_cost() == total_cost()
*/
double compare_cost() const
{
return CPU_COEFF*comp_cost;
}
double index_only_cost()
{
return IO_COEFF*idx_io_count*idx_avg_io_cost +
@@ -2814,14 +2834,15 @@ public:
bool is_zero() const
{
return io_count == 0.0 && idx_io_count == 0.0 && cpu_cost == 0.0 &&
import_cost == 0.0 && mem_cost == 0.0;
import_cost == 0.0 && mem_cost == 0.0 && comp_cost == 0.0;
}
void reset()
{
avg_io_cost= 1.0;
idx_avg_io_cost= 1.0;
io_count= idx_io_count= cpu_cost= idx_cpu_cost= mem_cost= import_cost= 0.0;
io_count= idx_io_count= cpu_cost= idx_cpu_cost= mem_cost= import_cost=
comp_cost= 0.0;
}
void multiply(double m)
@@ -2831,6 +2852,7 @@ public:
idx_io_count *= m;
idx_cpu_cost *= m;
import_cost *= m;
comp_cost *= m;
/* Don't multiply mem_cost */
}
@@ -2855,6 +2877,7 @@ public:
cpu_cost += cost->cpu_cost;
idx_cpu_cost += cost->idx_cpu_cost;
import_cost += cost->import_cost;
comp_cost+= cost->comp_cost;
}
void add_io(double add_io_cnt, double add_avg_cost)
@@ -2869,15 +2892,6 @@ public:
}
}
/// Add to CPU cost
void add_cpu(double add_cpu_cost) { cpu_cost+= add_cpu_cost; }
/// Add to import cost
void add_import(double add_import_cost) { import_cost+= add_import_cost; }
/// Add to memory cost
void add_mem(double add_mem_cost) { mem_cost+= add_mem_cost; }
/*
To be used when we go from old single value-based cost calculations to
the new Cost_estimate-based.