mirror of
https://github.com/MariaDB/server.git
synced 2025-01-29 02:05:57 +01:00
85 lines
2.5 KiB
C++
85 lines
2.5 KiB
C++
/*
|
|
Copyright (c) 2021, MariaDB Corporation.
|
|
|
|
This program is free software; you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License as published by
|
|
the Free Software Foundation; version 2 of the License.
|
|
|
|
This program is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
GNU General Public License for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with this program; if not, write to the Free Software
|
|
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1335 USA */
|
|
|
|
#include "sql_statistics.h"
|
|
|
|
/*
|
|
An equi-height histogram which stores real values for bucket bounds.
|
|
|
|
Handles @@histogram_type=JSON_HB
|
|
*/
|
|
|
|
class Histogram_json_hb : public Histogram_base
|
|
{
|
|
size_t size; /* Number of elements in the histogram */
|
|
|
|
/* Collection-time only: collected histogram in the JSON form. */
|
|
std::string json_text;
|
|
|
|
// Array of histogram bucket endpoints in KeyTupleFormat.
|
|
std::vector<std::string> histogram_bounds;
|
|
|
|
public:
|
|
static constexpr const char* JSON_NAME="histogram_hb_v1";
|
|
|
|
bool parse(MEM_ROOT *mem_root, Field *field, Histogram_type type_arg,
|
|
const char *hist_data, size_t hist_data_len) override;
|
|
|
|
void serialize(Field *field) override;
|
|
|
|
Histogram_builder *create_builder(Field *col, uint col_len,
|
|
ha_rows rows) override;
|
|
|
|
// returns number of buckets in the histogram
|
|
uint get_width() override
|
|
{
|
|
return (uint)size;
|
|
}
|
|
|
|
Histogram_type get_type() override
|
|
{
|
|
return JSON_HB;
|
|
}
|
|
|
|
/*
|
|
@brief
|
|
This used to be the size of the histogram on disk, which was redundant
|
|
(one can check the size directly). Return the number of buckets instead.
|
|
*/
|
|
uint get_size() override
|
|
{
|
|
return size;
|
|
}
|
|
|
|
void init_for_collection(MEM_ROOT *mem_root, Histogram_type htype_arg,
|
|
ulonglong size) override;
|
|
|
|
double point_selectivity(Field *field, key_range *endpoint,
|
|
double avg_selection) override;
|
|
double range_selectivity(Field *field, key_range *min_endp,
|
|
key_range *max_endp) override;
|
|
|
|
void set_json_text(ulonglong sz, uchar *json_text_arg)
|
|
{
|
|
size= (size_t) sz;
|
|
json_text.assign((const char*)json_text_arg,
|
|
strlen((const char*)json_text_arg));
|
|
}
|
|
|
|
private:
|
|
int find_bucket(Field *field, const uchar *lookup_val, bool equal_is_less);
|
|
};
|
|
|