#include <table_function.h>

Inheritance diagram for Table_function_json:

Public Member Functions
	Table_function_json (const char alias, Item a, List< Json_table_column > *cols)

	~Table_function_json () override

const char *	func_name () const override
	Returns function's name. More...

bool	init () override
	Initialize the table function before creation of result table. More...

bool	fill_result_table () override
	Execute table function. More...

table_map	used_tables () override
	Return table_map of tables used by function's data source. More...

bool	print (const THD thd, String str, enum_query_type query_type) const override
	JSON_TABLE printout. More...

bool	walk (Item_processor processor, enum_walk walk, uchar *arg) override

Public Member Functions inherited from Table_function
	Table_function ()

virtual	~Table_function ()=default

bool	create_result_table (THD thd, ulonglong options, const char table_alias)
	Create, but not instantiate the result table. More...

bool	write_row ()
	Write current record to the result table and handle overflow to disk. More...

Field *	get_field (uint i)
	Returns a field with given index. More...

void	empty_table ()
	Delete all rows in the table. More...

void	default_row ()
	Set the default row. More...

virtual bool	init_args ()
	Initialize table function after the result table has been created. More...

void	cleanup ()
	Clean up table function after one execution. More...

void	destroy ()
	Destroy table function object after all executions are complete. More...

Private Member Functions
bool	fill_json_table ()
	Fill the result table. More...

bool	init_json_table_col_lists (uint nest_idx, Json_table_column parent)
	Initialize columns and lists for json table. More...

void	set_subtree_to_null (Json_table_column root, Json_table_column *last)
	A helper function which sets all columns under given NESTED PATH column to nullptr. More...

List< Create_field > *	get_field_list () override
	Return list of fields to create result table from. More...

bool	do_init_args () override
	Check whether given default values can be saved to fields. More...

void	do_cleanup () override

Private Attributes
std::array< JT_data_source, MAX_NESTED_PATH >	m_jds
	Array of JSON Data Source for each NESTED PATH clause. More...

List< Json_table_column >	m_vt_list
	List of fields for tmp table creation. More...

List< Json_table_column > *	m_columns
	Tree of COLUMN clauses. More...

Mem_root_array< Json_table_column * >	m_all_columns
	Array of all columns - the flattened tree above. More...

const char *	m_table_alias
	JSON_TABLE's alias, for error reporting. More...

bool	is_source_parsed
	Whether source data has been parsed. More...

Item *	source
	JSON_TABLE's data source expression. More...

Additional Inherited Members
Protected Attributes inherited from Table_function
TABLE *	table
	Table function's result table. More...

bool	inited
	Whether the table function was already initialized. More...

Constructor & Destructor Documentation

◆ Table_function_json()

Table_function_json::Table_function_json	(	const char *	alias,
		Item *	a,
		List< Json_table_column > *	cols
	)

◆ ~Table_function_json()

Table_function_json::~Table_function_json ( )

inlineoverride

Member Function Documentation

◆ do_cleanup()

void Table_function_json::do_cleanup ( )

overrideprivatevirtual

Reimplemented from Table_function.

◆ do_init_args()

bool Table_function_json::do_init_args ( )

overrideprivatevirtual

Check whether given default values can be saved to fields.

Returns: true a conversion error occurred false defaults can be saved or aren't specified

Implements Table_function.

◆ fill_json_table()

bool Table_function_json::fill_json_table ( )

private

Fill the result table.

Fill json table.

Returns: true on error false on success

This function goes along the flattened list of columns and updates them by calling fill_column(). As it goes, it pushes all nested path nodes to 'nested' list, using it as a stack. After writing a row, it checks whether there's more data in the right-most nested path (top in the stack). If there is, it advances path's iterator, if no - pops the path from stack and goes to the next nested path (i.e more to left). When stack is empty, then the loop is over and all data (if any) was stored in the table, and function exits. Otherwise, the list of columns is positioned to the top nested path in the stack and incremented to the column after the nested path, then the loop of updating columns is executed again. So, whole execution could look as follows:

columns (                      <-- npr
  cr1,
  cr2,
  nested path .. columns (     <-- np1
    c11,
    nested path .. columns (   <-- np2
      c21
    )
  )
)

iteration | columns updated in the loop
1           npr cr1 cr2 np1 c11 np2 c21
2                                   c21
3                                   c21
4                           c11 np2 c21
5                                   c21
6                           c11 np2 c21
7                                   c21
8           npr cr1 cr2 np1 c11 np2 c21
9                                   c21

10 c11 np2 c21 Note that result table's row isn't automatically reset and if a column isn't updated, its data is written multiple times. E.g. cr1 in the example above is updated 2 times, but is written 10 times. This allows to save cycles on updating fields that for sure haven't been changed.

When there's sibling nested paths, i.e two or more nested paths in the same columns clause, then they're processed one at a time. Started with first, and the rest are set to null with help f set_subtree_to_null(). When the first sibling nested path runs out of rows, it's set to null and processing moves on to the next one.

Returns: false table filled true error occurred

◆ fill_result_table()

bool Table_function_json::fill_result_table ( )

overridevirtual

Execute table function.

Returns: true on error false on success

Implements Table_function.

◆ func_name()

const char * Table_function_json::func_name ( ) const

inlineoverridevirtual

Returns function's name.

Implements Table_function.

◆ get_field_list()

List< Create_field > * Table_function_json::get_field_list ( )

overrideprivatevirtual

Return list of fields to create result table from.

Implements Table_function.

◆ init()

bool Table_function_json::init ( void )

overridevirtual

Initialize the table function before creation of result table.

Returns: true on error false on success

Implements Table_function.

◆ init_json_table_col_lists()

bool Table_function_json::init_json_table_col_lists	(	uint *	nest_idx,
		Json_table_column *	parent
	)

private

Initialize columns and lists for json table.

This function does several things: 1) sets up list of fields (vt_list) for result table creation 2) fills array of all columns (m_all_columns) for execution 3) for each column that has default ON EMPTY or ON ERROR clauses, checks the value to be proper json and initializes column appropriately 4) for each column that involves path, the path is checked to be correct. The function goes recursively, starting from the top NESTED PATH clause and going in the depth-first way, traverses the tree of columns.

Parameters

nest_idx	index of parent's element in the nesting data array
parent	Parent of the NESTED PATH clause being initialized

Returns: false ok true an error occurred

◆ print()

bool Table_function_json::print	(	const THD *	thd,
		String *	str,
		enum_query_type	query_type
	)		const

overridevirtual

JSON_TABLE printout.

Parameters

thd	thread handler
str	string to print to
query_type	type of query

Returns: true on error false on success

Implements Table_function.

◆ set_subtree_to_null()

void Table_function_json::set_subtree_to_null	(	Json_table_column *	root,
		Json_table_column **	last
	)

private

A helper function which sets all columns under given NESTED PATH column to nullptr.

Used to evaluate sibling NESTED PATHS.

Parameters

	root	root NESTED PATH column
[out]	last	last column which belongs to the given NESTED PATH

◆ used_tables()

table_map Table_function_json::used_tables ( )

overridevirtual

Return table_map of tables used by function's data source.

Reimplemented from Table_function.

◆ walk()

bool Table_function_json::walk	(	Item_processor	processor,
		enum_walk	walk,
		uchar *	arg
	)

overridevirtual

Implements Table_function.

Member Data Documentation

◆ is_source_parsed

bool Table_function_json::is_source_parsed

private

Whether source data has been parsed.

◆ m_all_columns

Mem_root_array<Json_table_column *> Table_function_json::m_all_columns

private

Array of all columns - the flattened tree above.

◆ m_columns

List<Json_table_column>* Table_function_json::m_columns

private

Tree of COLUMN clauses.

◆ m_jds

std::array<JT_data_source, MAX_NESTED_PATH> Table_function_json::m_jds

private

Array of JSON Data Source for each NESTED PATH clause.

◆ m_table_alias

const char* Table_function_json::m_table_alias

private

JSON_TABLE's alias, for error reporting.

◆ m_vt_list

List<Json_table_column> Table_function_json::m_vt_list

private

List of fields for tmp table creation.

◆ source

Item* Table_function_json::source

private

JSON_TABLE's data source expression.

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

sql/table_function.h
sql/table_function.cc

Public Member Functions

Private Member Functions

Private Attributes

Additional Inherited Members

Constructor & Destructor Documentation

◆ Table_function_json()

◆ ~Table_function_json()

Member Function Documentation

◆ do_cleanup()

◆ do_init_args()

◆ fill_json_table()

◆ fill_result_table()

◆ func_name()

◆ get_field_list()

◆ init()

◆ init_json_table_col_lists()

◆ print()

◆ set_subtree_to_null()

◆ used_tables()

◆ walk()

Member Data Documentation

◆ is_source_parsed

◆ m_all_columns

◆ m_columns

◆ m_jds

◆ m_table_alias

◆ m_vt_list

◆ source