#include <singleton.h>

Inheritance diagram for histograms::Singleton< T >:

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

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

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

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

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

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

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

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

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	get_auto_update () const

void	set_auto_update (bool auto_update)
	Sets the auto update property for the histogram. More...

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, Time_val out, Error_context *context)

template<>
bool	extract_json_dom_value (const Json_dom json_dom, Datetime_val 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 Singleton< 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)
	Singleton 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
	Singleton (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)
	Singleton constructor. More...

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

bool	add_value_json_bucket (const double &value, Json_array *json_bucket)

bool	add_value_json_bucket (const String &value, Json_array *json_bucket)

bool	add_value_json_bucket (const ulonglong &value, Json_array *json_bucket)

bool	add_value_json_bucket (const longlong &value, Json_array *json_bucket)

bool	add_value_json_bucket (const Time_val &value, Json_array *json_bucket)

bool	add_value_json_bucket (const Datetime_val &value, Json_array *json_bucket)

bool	add_value_json_bucket (const my_decimal &value, Json_array *json_bucket)

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

static bool	add_value_json_bucket (const T &value, Json_array *json_bucket)
	Add value to a JSON bucket. More...

static bool	create_json_bucket (const SingletonBucket< T > &bucket, Json_array *json_bucket)
	Convert one bucket to a JSON object. More...

Private Attributes
Mem_root_array< SingletonBucket< T > >	m_buckets
	The buckets for this histogram [value, cumulative frequency]. 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...

static constexpr const char *	auto_update_str ()
	String representation of the JSON field "auto-update". 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

◆ Singleton() [1/3]

template<class T >

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

delete

◆ Singleton() [2/3]

template<class T >

histograms::Singleton< T >::Singleton	(	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

Singleton 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

◆ Singleton() [3/3]

template<class T >

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

private

Singleton 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

Member Function Documentation

◆ add_value_json_bucket() [1/8]

bool histograms::Singleton< Datetime_val >::add_value_json_bucket	(	const Datetime_val &	value,
		Json_array *	json_bucket
	)

private

◆ add_value_json_bucket() [2/8]

bool histograms::Singleton< double >::add_value_json_bucket	(	const double &	value,
		Json_array *	json_bucket
	)

private

◆ add_value_json_bucket() [3/8]

bool histograms::Singleton< longlong >::add_value_json_bucket	(	const longlong &	value,
		Json_array *	json_bucket
	)

private

◆ add_value_json_bucket() [4/8]

bool histograms::Singleton< my_decimal >::add_value_json_bucket	(	const my_decimal &	value,
		Json_array *	json_bucket
	)

private

◆ add_value_json_bucket() [5/8]

bool histograms::Singleton< String >::add_value_json_bucket	(	const String &	value,
		Json_array *	json_bucket
	)

private

◆ add_value_json_bucket() [6/8]

template<class T >

static bool histograms::Singleton< T >::add_value_json_bucket	(	const T &	value,
		Json_array *	json_bucket
	)

staticprivate

Add value to a JSON bucket.

This function adds the value to the supplied JSON array.

Parameters

	value	the value to add
[out]	json_bucket	a JSON array where the bucket data is to be stored

Returns: true on error, false otherwise

◆ add_value_json_bucket() [7/8]

bool histograms::Singleton< Time_val >::add_value_json_bucket	(	const Time_val &	value,
		Json_array *	json_bucket
	)

private

◆ add_value_json_bucket() [8/8]

bool histograms::Singleton< ulonglong >::add_value_json_bucket	(	const ulonglong &	value,
		Json_array *	json_bucket
	)

private

◆ build_histogram()

template<class T >

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

Build the Singleton histogram.

Parameters

value_map	values to create the histogram for
num_buckets	the number of buckets specified/requested by the user

Returns: true on error, false otherwise

◆ clone()

template<class T >

Histogram * histograms::Singleton< 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 >

Singleton< T > * histograms::Singleton< 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

Singleton histogram factory method.

Attempts to allocate and initialize a singleton 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 a Singleton histogram on success. Returns nullptr on error.

◆ create_json_bucket()

template<class T >

bool histograms::Singleton< T >::create_json_bucket	(	const SingletonBucket< T > &	bucket,
		Json_array *	json_bucket
	)

staticprivate

Convert one bucket to a JSON object.

Parameters

	bucket	the histogram bucket to convert
[out]	json_bucket	a JSON array where the bucket data is to be stored

Returns: true on error, false otherwise

◆ get_equal_to_selectivity()

template<class T >

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

Find the number of values equal to 'value'.

This function will estimate the number 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::Singleton< T >::get_greater_than_selectivity ( const T & value ) const

Find the number of values greater than 'value'.

This function will estimate the number 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::Singleton< T >::get_less_than_selectivity ( const T & value ) const

Find the number of values less than 'value'.

This function will estimate the number 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::Singleton< T >::get_num_buckets ( ) const

inlineoverridevirtual

Returns: number of values/buckets in this histogram

Implements histograms::Histogram.

◆ get_num_distinct_values()

template<class T >

size_t histograms::Singleton< T >::get_num_distinct_values ( ) const

inlineoverridevirtual

Get the estimated number of distinct non-NULL values.

Returns: number of distinct non-NULL values

TODO(christiani): If the histogram is based on sampling, then this estimate is potentially off by a factor 1/sampling_rate. It should be adjusted to an actual estimate if we are going to use it.

Implements histograms::Histogram.

◆ histogram_to_json()

template<class T >

bool histograms::Singleton< 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::Singleton< 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::Singleton< 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 Singleton histogram
context	error context for validation

Returns: true on error, false otherwise.

Implements histograms::Histogram.

◆ singleton_str()

template<class T >

static constexpr const char * histograms::Singleton< T >::singleton_str ( )

inlinestaticconstexprprivate

String representation of the histogram type SINGLETON.

Member Data Documentation

◆ m_buckets

template<class T >

Mem_root_array<SingletonBucket<T> > histograms::Singleton< T >::m_buckets

private

The buckets for this histogram [value, cumulative frequency].

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

sql/histograms/singleton.h
sql/histograms/singleton.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

◆ Singleton() [1/3]

◆ Singleton() [2/3]

◆ Singleton() [3/3]

Member Function Documentation

◆ add_value_json_bucket() [1/8]

◆ add_value_json_bucket() [2/8]

◆ add_value_json_bucket() [3/8]

◆ add_value_json_bucket() [4/8]

◆ add_value_json_bucket() [5/8]

◆ add_value_json_bucket() [6/8]

◆ add_value_json_bucket() [7/8]

◆ add_value_json_bucket() [8/8]

◆ build_histogram()

◆ clone()

◆ create()

◆ create_json_bucket()

◆ 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()

◆ singleton_str()

Member Data Documentation

◆ m_buckets