#include <equi_height.h>

Inheritance diagram for histograms::Equi_height< T >:

Public Member Functions
Histogram *	clone (MEM_ROOT *mem_root) const override
	Make a clone of this histogram on a MEM_ROOT. More...

	Equi_height (const Equi_height< T > &other)=delete

bool	build_histogram (const Value_map< T > &value_map, size_t num_buckets)
	Build the histogram. More...

double	get_equal_to_selectivity (const T &value) const
	Find the fraction of values equal to 'value'. More...

double	get_less_than_selectivity (const T &value) const
	Find the fraction of values that is less than 'value'. More...

double	get_greater_than_selectivity (const T &value) const
	Find the fraction of values that is greater than 'value'. More...

size_t	get_num_buckets () const override

size_t	get_num_distinct_values () const override
	Get the estimated number of distinct non-NULL values. More...

bool	histogram_to_json (Json_object *json_object) const override
	Convert this histogram to a JSON object. More...

const Mem_root_array< equi_height::Bucket< T > > &	get_buckets () const
	Get the buckets of the histogram. More...

std::string	histogram_type_to_str () const override
	Returns the histogram type as a readable string. More...

	Equi_height (MEM_ROOT mem_root, const Equi_height< String > &other, bool error)

Public Member Functions inherited from histograms::Histogram
	Histogram ()=delete

	Histogram (const Histogram &other)=delete

virtual	~Histogram ()=default
	Destructor. More...

MEM_ROOT *	get_mem_root () const

const LEX_CSTRING	get_database_name () const

const LEX_CSTRING	get_table_name () const

const LEX_CSTRING	get_column_name () const

enum_histogram_type	get_histogram_type () const

double	get_null_values_fraction () const

const CHARSET_INFO *	get_character_set () const

double	get_sampling_rate () const

Value_map_type	get_data_type () const

size_t	get_num_buckets_specified () const

bool	store_histogram (THD *thd) const
	Store this histogram to persistent storage (data dictionary). More...

bool	get_selectivity (Item *items, size_t item_count, enum_operator op, double selectivity) const
	Get selectivity estimation. More...

double	get_non_null_values_fraction () const

template<>
bool	extract_json_dom_value (const Json_dom json_dom, double out, Error_context *context)

template<>
bool	extract_json_dom_value (const Json_dom json_dom, String out, Error_context *context)

template<>
bool	extract_json_dom_value (const Json_dom json_dom, ulonglong out, Error_context *context)

template<>
bool	extract_json_dom_value (const Json_dom json_dom, longlong out, Error_context *context)

template<>
bool	extract_json_dom_value (const Json_dom json_dom, MYSQL_TIME out, Error_context *context)

template<>
bool	extract_json_dom_value (const Json_dom json_dom, my_decimal out, Error_context *context)

Static Public Member Functions
static Equi_height< T > *	create (MEM_ROOT *mem_root, const std::string &db_name, const std::string &tbl_name, const std::string &col_name, Value_map_type data_type)
	Equi-height histogram factory method. More...

Static Public Member Functions inherited from histograms::Histogram
static constexpr const char *	histogram_type_str ()
	String representation of the JSON field "histogram-type". More...

static constexpr const char *	data_type_str ()
	String representation of the JSON field "data-type". More...

static constexpr const char *	collation_id_str ()
	String representation of the JSON field "collation-id". More...

static constexpr const char *	singleton_str ()
	String representation of the histogram type SINGLETON. More...

static constexpr const char *	equi_height_str ()
	String representation of the histogram type EQUI-HEIGHT. More...

static Histogram *	json_to_histogram (MEM_ROOT mem_root, const std::string &schema_name, const std::string &table_name, const std::string &column_name, const Json_object &json_object, Error_context context)
	Converts JSON object to a histogram. More...

Protected Member Functions
bool	json_to_histogram (const Json_object &json_object, Error_context *context) override
	Populate this histogram with contents from a JSON object. More...

Protected Member Functions inherited from histograms::Histogram
	Histogram (MEM_ROOT mem_root, const std::string &db_name, const std::string &tbl_name, const std::string &col_name, enum_histogram_type type, Value_map_type data_type, bool error)
	Constructor. More...

	Histogram (MEM_ROOT mem_root, const Histogram &other, bool error)
	Copy constructor. More...

bool	histogram_data_type_to_json (Json_object *json_object) const
	Write the data type of this histogram into a JSON object. More...

template<class T >
bool	extract_json_dom_value (const Json_dom json_dom, T out, Error_context *context)
	Return the value that is contained in the JSON DOM object. More...

Private Member Functions
	Equi_height (MEM_ROOT mem_root, const std::string &db_name, const std::string &tbl_name, const std::string &col_name, Value_map_type data_type, bool error)
	Equi-height constructor. More...

	Equi_height (MEM_ROOT mem_root, const Equi_height< T > &other, bool error)
	Equi-height copy-constructor. More...

bool	add_bucket_from_json (const Json_array json_bucket, Error_context context)
	Create Equi-height buckets from a JSON array. More...

Static Private Member Functions
static constexpr const char *	equi_height_str ()
	String representation of the histogram type EQUI-HEIGHT. More...

Private Attributes
Mem_root_array< equi_height::Bucket< T > >	m_buckets
	The buckets for this histogram. More...

Additional Inherited Members
Public Types inherited from histograms::Histogram
enum class	enum_histogram_type { EQUI_HEIGHT , SINGLETON }
	All supported histogram types in MySQL. More...

Static Protected Member Functions inherited from histograms::Histogram
static constexpr const char *	buckets_str ()
	String representation of the JSON field "buckets". More...

static constexpr const char *	last_updated_str ()
	String representation of the JSON field "last-updated". More...

static constexpr const char *	null_values_str ()
	String representation of the JSON field "null-values". More...

static constexpr const char *	sampling_rate_str ()

static constexpr const char *	numer_of_buckets_specified_str ()
	String representation of the JSON field "number-of-buckets-specified". More...

Protected Attributes inherited from histograms::Histogram
double	m_sampling_rate

double	m_null_values_fraction
	The fraction of NULL values in the histogram (between 0.0 and 1.0). More...

const CHARSET_INFO *	m_charset
	The character set for the data stored. More...

size_t	m_num_buckets_specified
	The number of buckets originally specified. More...

Constructor & Destructor Documentation

◆ Equi_height() [1/4]

template<class T >

histograms::Equi_height< T >::Equi_height ( const Equi_height< T > & other )

delete

◆ Equi_height() [2/4]

template<class T >

histograms::Equi_height< T >::Equi_height	(	MEM_ROOT *	mem_root,
		const std::string &	db_name,
		const std::string &	tbl_name,
		const std::string &	col_name,
		Value_map_type	data_type,
		bool *	error
	)

private

Equi-height constructor.

This will not build the histogram, but only set its properties.

Parameters

	mem_root	the mem_root where the histogram contents will be allocated
	db_name	name of the database this histogram represents
	tbl_name	name of the table this histogram represents
	col_name	name of the column this histogram represents
	data_type	the type of data that this histogram contains
[out]	error	is set to true if an error occurs

◆ Equi_height() [3/4]

template<class T >

histograms::Equi_height< T >::Equi_height	(	MEM_ROOT *	mem_root,
		const Equi_height< T > &	other,
		bool *	error
	)

private

Equi-height copy-constructor.

This will take a copy of the histogram and all of its contents on the provided MEM_ROOT.

Parameters

	mem_root	the MEM_ROOT to allocate the new histogram on.
	other	the histogram to take a copy of
[out]	error	is set to true if an error occurs

◆ Equi_height() [4/4]

histograms::Equi_height< String >::Equi_height	(	MEM_ROOT *	mem_root,
		const Equi_height< String > &	other,
		bool *	error
	)

Member Function Documentation

◆ add_bucket_from_json()

template<class T >

bool histograms::Equi_height< T >::add_bucket_from_json	(	const Json_array *	json_bucket,
		Error_context *	context
	)

private

Create Equi-height buckets from a JSON array.

This function will add new buckets to the current histogram by going through the provided JSON array. Contents are allocated as needed on the current histograms MEM_ROOT.

Parameters

json_bucket	a JSON array containing the histogram buckets
context	error context for validation

Returns: true on error, false otherwise

◆ build_histogram()

template<class T >

bool histograms::Equi_height< T >::build_histogram	(	const Value_map< T > &	value_map,
		size_t	num_buckets
	)

Build the histogram.

This function will build a new histogram from a "value map". The function will create at most num_buckets buckets, but may use less.

Parameters

value_map	a value map, where the map key is a value and the map value is the absolute frequency for that value
num_buckets	maximum number of buckets to create

Returns: true on error, false otherwise

◆ clone()

template<class T >

Histogram * histograms::Equi_height< T >::clone ( MEM_ROOT * mem_root ) const

overridevirtual

Make a clone of this histogram on a MEM_ROOT.

Parameters

mem_root the MEM_ROOT to allocate the new histogram contents on.

Returns: a copy of the histogram allocated on the provided MEM_ROOT.

Implements histograms::Histogram.

◆ create()

template<class T >

Equi_height< T > * histograms::Equi_height< T >::create	(	MEM_ROOT *	mem_root,
		const std::string &	db_name,
		const std::string &	tbl_name,
		const std::string &	col_name,
		Value_map_type	data_type
	)

static

Equi-height histogram factory method.

Attempts to allocate and initialize an equi-height histogram on the supplied mem_root. This will not build the histogram, but only set its properties. If the attempt to allocate the histogram fails or if an error occurs during construction we return nullptr.

Parameters

mem_root	the mem_root where the histogram contents will be allocated
db_name	name of the database this histogram represents
tbl_name	name of the table this histogram represents
col_name	name of the column this histogram represents
data_type	the type of data that this histogram contains

Returns: A pointer to an equi-height histogram on success. Returns nullptr on error.

◆ equi_height_str()

template<class T >

static constexpr const char * histograms::Equi_height< T >::equi_height_str ( )

inlinestaticconstexprprivate

String representation of the histogram type EQUI-HEIGHT.

◆ get_buckets()

template<class T >

const Mem_root_array< equi_height::Bucket< T > > & histograms::Equi_height< T >::get_buckets ( ) const

inline

Get the buckets of the histogram.

Exposed for unit testing.

Returns: A const reference to the collection of buckets.

◆ get_equal_to_selectivity()

template<class T >

double histograms::Equi_height< T >::get_equal_to_selectivity ( const T & value ) const

Find the fraction of values equal to 'value'.

This function will estimate the fraction of values that is equal to the provided value.

Parameters

value The value to estimate the selectivity for.

Returns: The selectivity between 0.0 and 1.0 inclusive.

◆ get_greater_than_selectivity()

template<class T >

double histograms::Equi_height< T >::get_greater_than_selectivity ( const T & value ) const

Find the fraction of values that is greater than 'value'.

This function will estimate the fraction of values that is greater than the provided value.

Parameters

value The value to estimate the selectivity for.

Returns: the selectivity between 0.0 and 1.0 inclusive.

◆ get_less_than_selectivity()

template<class T >

double histograms::Equi_height< T >::get_less_than_selectivity ( const T & value ) const

Find the fraction of values that is less than 'value'.

This function will estimate the fraction of values that is less than the provided value.

Parameters

value The value to estimate the selectivity for.

Returns: the selectivity between 0.0 and 1.0 inclusive.

◆ get_num_buckets()

template<class T >

size_t histograms::Equi_height< T >::get_num_buckets ( ) const

inlineoverridevirtual

Returns: number of buckets in this histogram

Implements histograms::Histogram.

◆ get_num_distinct_values()

template<class T >

size_t histograms::Equi_height< T >::get_num_distinct_values

overridevirtual

Get the estimated number of distinct non-NULL values.

Returns: number of distinct non-NULL values

Implements histograms::Histogram.

◆ histogram_to_json()

template<class T >

bool histograms::Equi_height< T >::histogram_to_json ( Json_object * json_object ) const

overridevirtual

Convert this histogram to a JSON object.

This function will take the contents of the current histogram and put it in the output parameter "json_object".

Parameters

[in,out] json_object output where the histogram is to be stored The caller is responsible for allocating/deallocating the JSON object

Returns: true on error, false otherwise

Implements histograms::Histogram.

◆ histogram_type_to_str()

template<class T >

std::string histograms::Equi_height< T >::histogram_type_to_str

overridevirtual

Returns the histogram type as a readable string.

Returns: a readable string representation of the histogram type

Implements histograms::Histogram.

◆ json_to_histogram()

template<class T >

bool histograms::Equi_height< T >::json_to_histogram	(	const Json_object &	json_object,
		Error_context *	context
	)

overrideprotectedvirtual

Populate this histogram with contents from a JSON object.

Parameters

json_object	a JSON object that represents an Equi-height histogram
context	error context for validation

Returns: True on error, false otherwise.

Implements histograms::Histogram.

Member Data Documentation

◆ m_buckets

template<class T >

Mem_root_array<equi_height::Bucket<T> > histograms::Equi_height< T >::m_buckets

private

The buckets for this histogram.

The documentation for this class was generated from the following files:

sql/histograms/equi_height.h
sql/histograms/equi_height.cc

Public Member Functions

Static Public Member Functions

Protected Member Functions

Private Member Functions

Static Private Member Functions

Private Attributes

Additional Inherited Members

Constructor & Destructor Documentation

◆ Equi_height() [1/4]

◆ Equi_height() [2/4]

◆ Equi_height() [3/4]

◆ Equi_height() [4/4]

Member Function Documentation

◆ add_bucket_from_json()

◆ build_histogram()

◆ clone()

◆ create()

◆ equi_height_str()

◆ get_buckets()

◆ get_equal_to_selectivity()

◆ get_greater_than_selectivity()

◆ get_less_than_selectivity()

◆ get_num_buckets()

◆ get_num_distinct_values()

◆ histogram_to_json()

◆ histogram_type_to_str()

◆ json_to_histogram()

Member Data Documentation

◆ m_buckets