2012-08-27 05:13:14 +00:00
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#pragma once
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#include <Poco/SharedPtr.h>
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#include <DB/Columns/ColumnConst.h>
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#include <DB/Columns/ColumnArray.h>
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#include <DB/DataTypes/DataTypeArray.h>
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#include <DB/DataStreams/IProfilingBlockInputStream.h>
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namespace DB
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{
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/** Реализует операцию ARRAY JOIN.
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* (Для удобства, эта операция записывается, как функция arrayJoin, применённая к массиву.)
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* Эта операция размножает все строки столько раз, сколько элементов в массиве.
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* Результат функции arrayJoin - столбец единичных значений соответствующих элементов.
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*
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* Например,
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*
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* name arr
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* ------ ------
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* 'вася' [1, 2]
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* 'петя' []
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*
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* преобразуется в
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*
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* name arrayJoin(arr)
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* ------ --------------
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* 'вася' 1
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* 'вася' 2
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*/
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class ArrayJoiningBlockInputStream : public IProfilingBlockInputStream
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{
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public:
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ArrayJoiningBlockInputStream(BlockInputStreamPtr input_, ssize_t array_column_)
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2013-05-04 04:05:15 +00:00
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: array_column(array_column_)
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2012-08-27 05:13:14 +00:00
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{
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2013-05-04 04:05:15 +00:00
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children.push_back(input_);
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2012-08-27 05:13:14 +00:00
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}
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ArrayJoiningBlockInputStream(BlockInputStreamPtr input_, const String & array_column_name_)
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2013-05-04 04:05:15 +00:00
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: array_column(-1), array_column_name(array_column_name_)
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2012-08-27 05:13:14 +00:00
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{
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2013-05-04 04:05:15 +00:00
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children.push_back(input_);
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2012-08-27 05:13:14 +00:00
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}
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2012-10-20 02:10:47 +00:00
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String getName() const { return "ArrayJoiningBlockInputStream"; }
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2013-05-03 10:20:53 +00:00
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String getID() const
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{
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std::stringstream res;
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2013-05-04 05:20:07 +00:00
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res << "ArrayJoining(" << children.back()->getID() << ", " << array_column << ", " << array_column_name << ")";
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2013-05-03 10:20:53 +00:00
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return res.str();
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}
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2012-10-20 02:10:47 +00:00
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protected:
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2012-08-27 05:13:14 +00:00
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Block readImpl()
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{
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2013-05-04 05:20:07 +00:00
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Block block = children.back()->read();
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2012-08-27 05:13:14 +00:00
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if (!block)
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return block;
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if (-1 == array_column)
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array_column = block.getPositionByName(array_column_name);
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2012-09-19 19:30:18 +00:00
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ColumnPtr array = block.getByPosition(array_column).column;
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2012-08-27 05:13:14 +00:00
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if (array->isConst())
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array = dynamic_cast<const IColumnConst &>(*array).convertToFullColumn();
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size_t columns = block.columns();
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for (size_t i = 0; i < columns; ++i)
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{
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ColumnWithNameAndType & current = block.getByPosition(i);
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2012-10-20 02:10:47 +00:00
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2012-08-27 05:13:14 +00:00
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if (static_cast<ssize_t>(i) == array_column)
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{
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ColumnWithNameAndType result;
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result.column = dynamic_cast<const ColumnArray &>(*current.column).getDataPtr();
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result.type = dynamic_cast<const DataTypeArray &>(*current.type).getNestedType();
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result.name = "arrayJoin(" + current.name + ")";
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block.erase(i);
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2012-09-19 19:30:18 +00:00
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block.insert(i, result);
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2012-08-27 05:13:14 +00:00
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}
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else
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2013-05-03 05:23:14 +00:00
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current.column = current.column->replicate(dynamic_cast<const ColumnArray &>(*array).getOffsets());
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2012-08-27 05:13:14 +00:00
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}
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return block;
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}
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private:
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ssize_t array_column;
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String array_column_name;
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};
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}
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