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Split histogram classes and into JSON and binary classes

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Signed-off-by: Michael Okoko <okokomichaels@outlook.com>
This commit is contained in:
Michael Okoko
2021-07-28 05:19:06 +01:00
committed by Sergei Petrunia
parent 1998b787ac
commit 1fa7af749e
2 changed files with 132 additions and 39 deletions
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92
sql/sql_statistics.h
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@ -153,6 +153,24 @@ public:
virtual void serialize(Field *to_field)= 0;
virtual Histogram_type get_type()=0;
virtual uint get_width()=0;
virtual void init_for_collection(MEM_ROOT *mem_root, Histogram_type htype_arg, ulonglong size)=0;
virtual bool is_available()=0;
virtual bool is_usable(THD *thd)=0;
virtual void set_values(uchar * values)=0;
virtual uchar *get_values()=0;
virtual void set_size(ulonglong sz)=0;
virtual double range_selectivity(double min_pos, double max_pos)=0;
virtual double point_selectivity(double pos, double avg_selection)=0;
// Legacy: return the size of the histogram on disk.
// This will be stored in mysql.column_stats.hist_size column.
@ -162,22 +180,21 @@ public:
virtual ~Histogram_base(){}
};
class Histogram : public Histogram_base
class Histogram_binary : public Histogram_base
{
public:
bool parse(MEM_ROOT *mem_root, Histogram_type type_arg,
const uchar *ptr_arg, uint size_arg) override;
void serialize(Field *to_field) override;
Histogram_type get_type() override { return type; }
uint get_size() override { return (uint) size; }
// returns number of buckets in the histogram
uint get_width()
uint get_width() override
{
switch (type) {
case SINGLE_PREC_HB:
case JSON:
return size;
case DOUBLE_PREC_HB:
return size / 2;
@ -196,7 +213,6 @@ private:
{
switch (type) {
case SINGLE_PREC_HB:
case JSON:
return ((uint) (1 << 8) - 1);
case DOUBLE_PREC_HB:
return ((uint) (1 << 16) - 1);
@ -211,7 +227,6 @@ private:
DBUG_ASSERT(i < get_width());
switch (type) {
case SINGLE_PREC_HB:
case JSON:
return (uint) (((uint8 *) values)[i]);
case DOUBLE_PREC_HB:
return (uint) uint2korr(values + i * 2);
@ -260,22 +275,22 @@ private:
return i;
}
uchar *get_values() { return (uchar *) values; }
uchar *get_values() override { return (uchar *) values; }
public:
void init_for_collection(MEM_ROOT *mem_root, Histogram_type htype_arg, ulonglong size);
void init_for_collection(MEM_ROOT *mem_root, Histogram_type htype_arg, ulonglong size) override;
// Note: these two are used only for saving the JSON text:
void set_values (uchar *vals) { values= (uchar *) vals; }
void set_size (ulonglong sz) { size= (uint8) sz; }
void set_values (uchar *vals) override { values= (uchar *) vals; }
void set_size (ulonglong sz) override { size= (uint8) sz; }
bool is_available() { return get_size() > 0 && get_values(); }
bool is_available() override { return get_size() > 0 && get_values(); }
/*
This function checks that histograms should be usable only when
1) the level of optimizer_use_condition_selectivity > 3
2) histograms have been collected
*/
bool is_usable(THD *thd)
bool is_usable(THD *thd) override
{
return thd->variables.optimizer_use_condition_selectivity > 3 &&
is_available();
@ -285,7 +300,6 @@ public:
{
switch (type) {
case SINGLE_PREC_HB:
case JSON:
((uint8 *) values)[i]= (uint8) (val * prec_factor());
return;
case DOUBLE_PREC_HB:
@ -301,7 +315,6 @@ public:
{
switch (type) {
case SINGLE_PREC_HB:
case JSON:
((uint8 *) values)[i]= ((uint8 *) values)[i-1];
return;
case DOUBLE_PREC_HB:
@ -313,7 +326,7 @@ public:
}
}
double range_selectivity(double min_pos, double max_pos)
double range_selectivity(double min_pos, double max_pos) override
{
double sel;
double bucket_sel= 1.0/(get_width() + 1);
@ -326,9 +339,54 @@ public:
/*
Estimate selectivity of "col=const" using a histogram
*/
double point_selectivity(double pos, double avg_sel);
double point_selectivity(double pos, double avg_sel) override;
};
class Histogram_json : public Histogram_base
{
private:
Histogram_type type;
uint8 size; /* Number of elements in the histogram*/
uchar *values;
public:
bool parse(MEM_ROOT *mem_root, Histogram_type type_arg, const uchar *ptr, uint size) override {return false;}
void serialize(Field *to_field) override{}
uint get_size() override {return (uint) size;}
// returns number of buckets in the histogram
uint get_width() override
{
return size;
};
Histogram_type get_type() override
{
return JSON;
}
void set_size (ulonglong sz) override {size = (uint8) sz; }
void init_for_collection(MEM_ROOT *mem_root, Histogram_type htype_arg, ulonglong size) override;
bool is_available() override {return get_size() > 0 && get_values(); }
bool is_usable(THD *thd) override
{
return thd->variables.optimizer_use_condition_selectivity > 3 &&
is_available();
}
void set_values (uchar *vals) override { values= (uchar *) vals; }
uchar *get_values() override { return (uchar *) values; }
double range_selectivity(double min_pos, double max_pos) override {return 0.1;}
double point_selectivity(double pos, double avg_selection) override {return 0.5;}
};
class Columns_statistics;
class Index_statistics;
@ -411,7 +469,7 @@ private:
public:
Histogram_type histogram_type_on_disk;
Histogram *histogram_;
Histogram_base *histogram_;
uint32 no_values_provided_bitmap()
{