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Use generic Histogram_base class for Histogram_builders

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This fixes the wrong calculation for avg_frequency in json histograms
by replacing the specific histogram objects with the generic Histogram_base class.

It also restores get/set size functions as they were useful in calculating fields
for binary histogram.

Signed-off-by: Michael Okoko <okokomichaels@outlook.com>
This commit is contained in:
Michael Okoko 2021-08-11 06:58:18 +01:00 committed by Sergei Petrunia
parent 21e0f5487f
commit 69f24c238e
3 changed files with 32 additions and 44 deletions
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10
mysql-test/main/statistics_json.result
View file

@ -19,7 +19,7 @@ test.t1 analyze status Engine-independent statistics collected
test.t1 analyze status OK
SELECT * FROM mysql.column_stats WHERE table_name='t1';
db_name table_name column_name min_value max_value nulls_ratio avg_length avg_frequency hist_size hist_type histogram
test t1 a 1 25 0.0000 4.0000 0.0000 10 JSON [
test t1 a 1 25 0.0000 4.0000 1.0000 10 JSON [
"3",
"5",
"7",
@ -31,7 +31,7 @@ test t1 a 1 25 0.0000 4.0000 0.0000 10 JSON [
"21",
"23"
]
test t1 b 1 9 0.0000 1.6400 0.0000 10 JSON [
test t1 b 1 9 0.0000 1.6400 1.0000 10 JSON [
"11",
"13",
"15",
@ -43,7 +43,7 @@ test t1 b 1 9 0.0000 1.6400 0.0000 10 JSON [
"5",
"7"
]
test t1 c 1 9 0.0000 2.0000 0.0000 10 JSON [
test t1 c 1 9 0.0000 2.0000 1.0000 10 JSON [
"11",
"13",
"15",
@ -55,7 +55,7 @@ test t1 c 1 9 0.0000 2.0000 0.0000 10 JSON [
"5",
"7"
]
test t1 d 1 25 0.0000 8.0000 0.0000 10 JSON [
test t1 d 1 25 0.0000 8.0000 1.0000 10 JSON [
"3",
"5",
"7",
@ -101,7 +101,7 @@ ERROR HY000: Failed to parse histogram, encountered JSON_TYPE '1'.
UPDATE mysql.column_stats SET histogram='{}' WHERE table_name='t1';
FLUSH TABLES;
SELECT * FROM t1;
ERROR HY000: Failed to parse histogram, encountered JSON_TYPE '32608'.
ERROR HY000: Failed to parse histogram, encountered JSON_TYPE '32641'.
DELETE FROM mysql.column_stats;
DROP TABLE t1;
create schema world;

48
sql/sql_statistics.cc
View file

@ -1082,7 +1082,7 @@ public:
// Note: this is dumb. the histogram size is stored with the
// histogram!
stat_field->store(stats->histogram_?
stats->histogram_->get_width() : 0);
stats->histogram_->get_size() : 0);
break;
case COLUMN_STAT_HIST_TYPE:
if (stats->histogram_)
@ -1269,7 +1269,7 @@ bool Histogram_binary::parse(MEM_ROOT *mem_root, Field *, Histogram_type type_ar
*/
void Histogram_binary::serialize(Field *field)
{
field->store((char*)get_values(), get_width(), &my_charset_bin);
field->store((char*)get_values(), get_size(), &my_charset_bin);
}
void Histogram_binary::init_for_collection(MEM_ROOT *mem_root,
@ -1292,6 +1292,7 @@ void Histogram_json::init_for_collection(MEM_ROOT *mem_root, Histogram_type htyp
bool Histogram_json::parse(MEM_ROOT *mem_root, Field *field, Histogram_type type_arg, const uchar *ptr, uint size_arg)
{
DBUG_ENTER("Histogram_json::parse");
size = (uint8) size_arg;
type = type_arg;
const char *json = (char *)ptr;
int vt;
@ -1545,7 +1546,7 @@ double Histogram_json::range_selectivity_new(Field *field, key_range *min_endp,
void Histogram_json::serialize(Field *field)
{
field->store((char*)values, strlen((char*)values),
field->store((char*)get_values(), strlen((char*)get_values()),
&my_charset_bin);
}
@ -1866,13 +1867,13 @@ public:
class Histogram_builder
{
private:
public:
Field *column; /* table field for which the histogram is built */
uint col_length; /* size of this field */
ha_rows records; /* number of records the histogram is built for */
Field *min_value; /* pointer to the minimal value for the field */
Field *max_value; /* pointer to the maximal value for the field */
Histogram_binary *histogram; /* the histogram location */
Histogram_base *histogram; /* the histogram location */
uint hist_width; /* the number of points in the histogram */
double bucket_capacity; /* number of rows in a bucket of the histogram */
uint curr_bucket; /* number of the current bucket to be built */
@ -1881,14 +1882,13 @@ private:
/* number of distinct values that occured only once */
ulonglong count_distinct_single_occurence;
public:
Histogram_builder(Field *col, uint col_len, ha_rows rows)
: column(col), col_length(col_len), records(rows)
{
Column_statistics *col_stats= col->collected_stats;
min_value= col_stats->min_value;
max_value= col_stats->max_value;
histogram= dynamic_cast<Histogram_binary *>(col_stats->histogram_);
histogram= col_stats->histogram_;
hist_width= histogram->get_width();
bucket_capacity= (double) records / (hist_width + 1);
curr_bucket= 0;
@ -1918,13 +1918,13 @@ public:
if (count > bucket_capacity * (curr_bucket + 1))
{
column->store_field_value((uchar *) elem, col_length);
histogram->set_value(curr_bucket,
((Histogram_binary *)histogram)->set_value(curr_bucket,
column->pos_in_interval(min_value, max_value));
curr_bucket++;
while (curr_bucket != hist_width &&
count > bucket_capacity * (curr_bucket + 1))
{
histogram->set_prev_value(curr_bucket);
((Histogram_binary *)histogram)->set_prev_value(curr_bucket);
curr_bucket++;
}
}
@ -1934,35 +1934,13 @@ public:
class Histogram_builder_json : public Histogram_builder
{
Field *column; /* table field for which the histogram is built */
uint col_length; /* size of this field */
ha_rows records; /* number of records the histogram is built for */
Field *min_value; /* pointer to the minimal value for the field */
Field *max_value; /* pointer to the maximal value for the field */
Histogram_json *histogram; /* the histogram location */
uint hist_width; /* the number of points in the histogram */
double bucket_capacity; /* number of rows in a bucket of the histogram */
uint curr_bucket; /* number of the current bucket to be built */
ulonglong count; /* number of values retrieved */
ulonglong count_distinct; /* number of distinct values retrieved */
/* number of distinct values that occured only once */
ulonglong count_distinct_single_occurence;
std::vector<std::string> bucket_bounds = {};
std::vector<std::string> bucket_bounds;
public:
Histogram_builder_json(Field *col, uint col_len, ha_rows rows)
: column(col), col_length(col_len), records(rows)
: Histogram_builder(col, col_len, rows)
{
Column_statistics *col_stats= col->collected_stats;
min_value= col_stats->min_value;
max_value= col_stats->max_value;
histogram= dynamic_cast<Histogram_json *>(col_stats->histogram_);
hist_width= histogram->get_width();
bucket_capacity= (double) records / (hist_width + 1);
curr_bucket= 0;
count= 0;
count_distinct= 0;
count_distinct_single_occurence= 0;
bucket_bounds = {};
}
~Histogram_builder_json() override = default;
@ -1995,7 +1973,7 @@ public:
writer->end_array();
histogram->set_size(bucket_bounds.size());
Binary_string *json_string = (Binary_string *) writer->output.get_string();
histogram->set_values((uchar *) json_string->c_ptr());
((Histogram_json *)histogram)->set_values((uchar *) json_string->c_ptr());
}
};

18
sql/sql_statistics.h
View file

@ -179,7 +179,11 @@ public:
return 1.0;
};
virtual ~Histogram_base(){}
// Legacy: return the size of the histogram on disk.
// This will be stored in mysql.column_stats.hist_size column.
// Newer, JSON-based histograms may return 0.
virtual uint get_size()=0;
virtual ~Histogram_base()= default;
};
class Histogram_binary : public Histogram_base
@ -283,7 +287,9 @@ public:
void set_values (uchar *vals) override { values= (uchar *) vals; }
void set_size (ulonglong sz) override { size= (uint8) sz; }
bool is_available() override { return get_width() > 0 && get_values(); }
uint get_size() override {return (uint)size;}
bool is_available() override { return get_size() > 0 && get_values(); }
/*
This function checks that histograms should be usable only when
@ -385,6 +391,10 @@ public:
void set_size (ulonglong sz) override {size = (uint8) sz; }
uint get_size() override {
return size;
}
void init_for_collection(MEM_ROOT *mem_root, Histogram_type htype_arg, ulonglong size) override;
bool is_available() override {return get_width() > 0 /*&& get_values()*/; }
@ -395,9 +405,9 @@ public:
is_available();
}
void set_values (uchar *vals) override { values= vals; }
void set_values (uchar *vals) override { values= (uchar *) vals; }
uchar *get_values() override { return values; }
uchar *get_values() override { return (uchar *) values; }
double range_selectivity(double min_pos, double max_pos) override {return 0.1;}