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We should eventually remove DTCollation from non-string items, as it's always initialized to DTCollation_numeric() and therefore wastes memory.
As a step to this, let's move the following members from Type_std_attributes:
- max_length
- decimals
- unsigned_flag
into a new class Type_numeric_attributes and derive Type_std_attributes from it.
Let's also add a new virtual method in Field:
virtual Type_numeric_attributes type_numeric_attributes() const;
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and turn Field::type_std_attributes() from a virtual to a non-virtual method like this:
Type_std_attributes type_std_attributes() const
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{
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return Type_std_attributes(type_numeric_attributes(), dtcollation());
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}
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All former Type_std_attributes methods that operate on only the moved members should also move to class Type_numeric_attributes.
As a result, the classes will look about like this:
class Type_numeric_attributes
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{
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public:
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static uint count_unsigned(Item **item, uint nitems);
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static uint32 find_max_char_length(Item **item, uint nitems);
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static uint32 find_max_octet_length(Item **item, uint nitems);
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static int find_max_decimal_int_part(Item **item, uint nitems);
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static uint find_max_decimals(Item **item, uint nitems);
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public:
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/*
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The maximum value length in characters multiplied by collation->mbmaxlen.
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Almost always it's the maximum value length in bytes.
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*/
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uint32 max_length;
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uint decimals;
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bool unsigned_flag;
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public:
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Type_numeric_attributes()
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:max_length(0), decimals(0), unsigned_flag(false)
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{ }
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Type_numeric_attributes(uint32 max_length_arg, uint decimals_arg,
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bool unsigned_flag_arg)
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:max_length(max_length_arg),
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decimals(decimals_arg),
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unsigned_flag(unsigned_flag_arg)
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{ }
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protected:
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void aggregate_numeric_attributes_real(Item **item, uint nitems);
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void aggregate_numeric_attributes_decimal(Item **item, uint nitems,
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bool unsigned_arg);
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};
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class Type_std_attributes: public Type_numeric_attributes
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{
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public:
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DTCollation collation;
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Type_std_attributes()
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:collation(&my_charset_bin, DERIVATION_COERCIBLE)
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{ }
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Type_std_attributes(const Type_numeric_attributes &nattr,
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const DTCollation &dtc)
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:Type_numeric_attributes(nattr), collation(dtc)
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{ }
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...
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};
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