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clickhouse: leaving the smallest column instead of the first [#CONV-2807].

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This commit is contained in:
Michael Kolupaev 2013-06-10 14:24:40 +00:00
parent 078f598ea0
commit 8a738aee11
1 changed files with 24 additions and 2 deletions
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26
dbms/src/Interpreters/ExpressionActions.cpp
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@ -371,6 +371,25 @@ void ExpressionActions::execute(Block & block) const
} }
} }
static std::string getAnyColumn(const NamesAndTypesList & columns)
{
NamesAndTypesList::const_iterator it = columns.begin();
size_t min_size = it->second->isNumeric() ? it->second->getSizeOfField() : 100;
String res = it->first;
for (; it != columns.end(); ++it)
{
size_t current_size = it->second->isNumeric() ? it->second->getSizeOfField() : 100;
if (current_size < min_size)
{
min_size = current_size;
res = it->first;
}
}
return res;
}
void ExpressionActions::finalize(const Names & output_columns) void ExpressionActions::finalize(const Names & output_columns)
{ {
typedef std::set<std::string> NameSet; typedef std::set<std::string> NameSet;
@ -385,6 +404,10 @@ void ExpressionActions::finalize(const Names & output_columns)
final_columns.insert(name); final_columns.insert(name);
} }
/// Не будем блок пустым, чтобы не потерять количество строк в нем.
if (final_columns.empty())
final_columns.insert(getAnyColumn(input_columns));
NameSet used_columns = final_columns; NameSet used_columns = final_columns;
for (size_t i = 0; i < actions.size(); ++i) for (size_t i = 0; i < actions.size(); ++i)
@ -413,8 +436,7 @@ void ExpressionActions::finalize(const Names & output_columns)
for (int i = static_cast<int>(sample_block.columns()) - 1; i >= 0; --i) for (int i = static_cast<int>(sample_block.columns()) - 1; i >= 0; --i)
{ {
const std::string & name = sample_block.getByPosition(i).name; const std::string & name = sample_block.getByPosition(i).name;
/// Не удаляем последний столбец. if (!final_columns.count(name))
if (!final_columns.count(name) && sample_block.columns() > 1)
add(Action::removeColumn(name)); add(Action::removeColumn(name));
} }
} }