ClickHouse/dbms/Dictionaries/DictionarySourceHelpers.cpp

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#include "DictionarySourceHelpers.h"
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#include <Columns/ColumnsNumber.h>
#include <Core/Block.h>
#include <Core/ColumnWithTypeAndName.h>
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#include <DataStreams/IBlockOutputStream.h>
#include <DataTypes/DataTypesNumber.h>
#include <IO/WriteHelpers.h>
#include "DictionaryStructure.h"
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namespace DB
{
/// For simple key
void formatIDs(BlockOutputStreamPtr & out, const std::vector<UInt64> & ids)
{
auto column = ColumnUInt64::create(ids.size());
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memcpy(column->getData().data(), ids.data(), ids.size() * sizeof(ids.front()));
Block block{{std::move(column), std::make_shared<DataTypeUInt64>(), "id"}};
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out->writePrefix();
out->write(block);
out->writeSuffix();
out->flush();
}
/// For composite key
void formatKeys(
const DictionaryStructure & dict_struct,
BlockOutputStreamPtr & out,
const Columns & key_columns,
const std::vector<size_t> & requested_rows)
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{
Block block;
for (size_t i = 0, size = key_columns.size(); i < size; ++i)
{
const ColumnPtr & source_column = key_columns[i];
auto filtered_column = source_column->cloneEmpty();
filtered_column->reserve(requested_rows.size());
for (size_t idx : requested_rows)
filtered_column->insertFrom(*source_column, idx);
block.insert({std::move(filtered_column), (*dict_struct.key)[i].type, toString(i)});
}
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out->writePrefix();
out->write(block);
out->writeSuffix();
out->flush();
}
}