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MDEV-9522 Split sql_select.cc:can_change_cond_ref_to_const into virtual methods in Type_handler

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This commit is contained in:
Alexander Barkov
2017-01-13 17:25:16 +04:00
parent 306ce497a7
commit 59c58f6ec3
4 changed files with 151 additions and 69 deletions
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46
sql/sql_type.h
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@ -32,6 +32,7 @@ class Item_func_hex;
class Item_hybrid_func;
class Item_func_min_max;
class Item_func_hybrid_field_type;
class Item_bool_func2;
class Item_func_between;
class Item_func_in;
class cmp_item;
@ -346,6 +347,31 @@ public:
virtual uint32 max_display_length(const Item *item) const= 0;
virtual int Item_save_in_field(Item *item, Field *field,
bool no_conversions) const= 0;
/**
Check if
WHERE expr=value AND expr=const
can be rewritten as:
WHERE const=value AND expr=const
"this" is the comparison handler that is used by "target".
@param target - the predicate expr=value,
whose "expr" argument will be replaced to "const".
@param target_expr - the target's "expr" which will be replaced to "const".
@param target_value - the target's second argument, it will remain unchanged.
@param source - the equality predicate expr=const (or expr<=>const)
that can be used to rewrite the "target" part
(under certain conditions, see the code).
@param source_expr - the source's "expr". It should be exactly equal to
the target's "expr" to make condition rewrite possible.
@param source_const - the source's "const" argument, it will be inserted
into "target" instead of "expr".
*/
virtual bool
can_change_cond_ref_to_const(Item_bool_func2 *target,
Item *target_expr, Item *target_value,
Item_bool_func2 *source,
Item *source_expr, Item *source_const) const= 0;
virtual Item_cache *Item_get_cache(THD *thd, const Item *item) const= 0;
virtual bool set_comparator_func(Arg_comparator *cmp) const= 0;
virtual bool Item_hybrid_func_fix_attributes(THD *thd, Item_hybrid_func *func,
@ -455,6 +481,14 @@ public:
DBUG_ASSERT(0);
return 1;
}
bool can_change_cond_ref_to_const(Item_bool_func2 *target,
Item *target_expr, Item *target_value,
Item_bool_func2 *source,
Item *source_expr, Item *source_const) const
{
DBUG_ASSERT(0);
return false;
}
Item_cache *Item_get_cache(THD *thd, const Item *item) const;
bool set_comparator_func(Arg_comparator *cmp) const;
bool Item_hybrid_func_fix_attributes(THD *thd, Item_hybrid_func *func,
@ -558,6 +592,10 @@ public:
bool Item_func_min_max_get_date(Item_func_min_max*,
MYSQL_TIME *, ulonglong fuzzydate) const;
virtual ~Type_handler_numeric() { }
bool can_change_cond_ref_to_const(Item_bool_func2 *target,
Item *target_expr, Item *target_value,
Item_bool_func2 *source,
Item *source_expr, Item *source_const) const;
};
@ -699,6 +737,10 @@ public:
const Type_std_attributes *item,
SORT_FIELD_ATTR *attr) const;
uint32 max_display_length(const Item *item) const;
bool can_change_cond_ref_to_const(Item_bool_func2 *target,
Item *target_expr, Item *target_value,
Item_bool_func2 *source,
Item *source_expr, Item *source_const) const;
Item_cache *Item_get_cache(THD *thd, const Item *item) const;
bool set_comparator_func(Arg_comparator *cmp) const;
bool Item_sum_hybrid_fix_length_and_dec(Item_sum_hybrid *func) const;
@ -746,6 +788,10 @@ public:
SORT_FIELD_ATTR *attr) const;
uint32 max_display_length(const Item *item) const;
int Item_save_in_field(Item *item, Field *field, bool no_conversions) const;
bool can_change_cond_ref_to_const(Item_bool_func2 *target,
Item *target_expr, Item *target_value,
Item_bool_func2 *source,
Item *source_expr, Item *source_const) const;
Item_cache *Item_get_cache(THD *thd, const Item *item) const;
bool set_comparator_func(Arg_comparator *cmp) const;
bool Item_hybrid_func_fix_attributes(THD *thd, Item_hybrid_func *func,