Cached_item Class Reference

This is used for segregating rows in groups (e.g. More...

#include <item.h>

Inheritance diagram for Cached_item:

Public Member Functions
virtual	~Cached_item ()=default
virtual bool	cmp ()=0
	Compare the value associated with the item with the stored value. More...
Item *	get_item () const
Item **	get_item_ptr ()

Public Attributes
bool	null_value {true}

Protected Member Functions
	Cached_item (Item *i)

Protected Attributes
Item *	item
	The item whose value to cache. More...

Detailed Description

This is used for segregating rows in groups (e.g.

GROUP BY, windows), to detect boundaries of groups. It caches a value, which is representative of the group, and can compare it to another row, and update its value when entering a new group.

Constructor & Destructor Documentation

Cached_item()

Cached_item::Cached_item ( Item *  i )

inlineexplicitprotected

~Cached_item()

virtual Cached_item::~Cached_item ( )

virtualdefault

Member Function Documentation

cmp()

virtual bool Cached_item::cmp ( )

pure virtual

Compare the value associated with the item with the stored value.

If they are different, update the stored value with item's value and return true.

Returns

true if item's value and stored value are different. Notice that first call is to establish an initial value and return value should be ignored.

Implemented in Cached_item_str, Cached_item_json, Cached_item_real, Cached_item_int, Cached_item_temporal, and Cached_item_decimal.

get_item()

Item * Cached_item::get_item ( ) const

inline

get_item_ptr()

Item ** Cached_item::get_item_ptr ( )

inline

Member Data Documentation

item

Item* Cached_item::item

protected

The item whose value to cache.

null_value

bool Cached_item::null_value {true}

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

• sql/item.h