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Added some comments and fixed some format

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This commit is contained in:
Alfonso Martinez 2022-09-27 10:20:54 +02:00
parent bb8a96b6d9
commit b4f481e724
1 changed files with 13 additions and 5 deletions
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14
src/Functions/FunctionsJSON.cpp
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@ -824,8 +824,7 @@ struct JSONExtractTree
class LowCardinalityFixedStringNode : public Node class LowCardinalityFixedStringNode : public Node
{ {
public: public:
LowCardinalityFixedStringNode(const size_t fixed_length_) LowCardinalityFixedStringNode(const size_t fixed_length_) : fixed_length(fixed_length_) {}
: fixed_length(fixed_length_) {}
bool insertResultToColumn(IColumn & dest, const Element & element) override bool insertResultToColumn(IColumn & dest, const Element & element) override
{ {
auto str = element.getString(); auto str = element.getString();
@ -833,12 +832,15 @@ struct JSONExtractTree
if (str.size() > fixed_length) if (str.size() > fixed_length)
return false; return false;
// For the non low cardinality case of FixedString, the padding is done in the FixedString Column implementation.
// In order to avoid having to pass the data to a FixedString Column and read it back (which would slow down the execution)
// the data is padded here and writen directly to the Low Cardinality Column
auto padded_str = str.data() + std::string(fixed_length - std::min(fixed_length, str.length()), '\0'); auto padded_str = str.data() + std::string(fixed_length - std::min(fixed_length, str.length()), '\0');
assert_cast<ColumnLowCardinality &>(dest).insertData(padded_str.data(), padded_str.size()); assert_cast<ColumnLowCardinality &>(dest).insertData(padded_str.data(), padded_str.size());
return true; return true;
} }
private: private:
const size_t fixed_length; const size_t fixed_length;
}; };
@ -880,6 +882,7 @@ struct JSONExtractTree
assert_cast<ColumnDecimal<DecimalType> &>(dest).insert(result); assert_cast<ColumnDecimal<DecimalType> &>(dest).insert(result);
return true; return true;
} }
private: private:
DataTypePtr data_type; DataTypePtr data_type;
}; };
@ -1128,6 +1131,11 @@ struct JSONExtractTree
case TypeIndex::UUID: return std::make_unique<UUIDNode>(); case TypeIndex::UUID: return std::make_unique<UUIDNode>();
case TypeIndex::LowCardinality: case TypeIndex::LowCardinality:
{ {
// The low cardinality case is treated in two different ways:
// For FixedString type, an especial class is implemented for inserting the data in the destination column,
// as the string length must be passed in order to check and pad the incoming data.
// For the rest of low cardinality types, the insertion is done in their corresponding class, adapting the data
// as needed for the insertData function of the ColumnLowCardinality.
auto dictionary_type = typeid_cast<const DataTypeLowCardinality *>(type.get())->getDictionaryType(); auto dictionary_type = typeid_cast<const DataTypeLowCardinality *>(type.get())->getDictionaryType();
if ((*dictionary_type).getTypeId() == TypeIndex::FixedString) if ((*dictionary_type).getTypeId() == TypeIndex::FixedString)
{ {