bool filterBlockWithQuery(ASTPtr query, Block & block, const Context & context)
{
query = query->clone();
const ASTSelectQuery & select = typeid_cast<ASTSelectQuery & >(*query);
if (!select.where_expression && !select.prewhere_expression)
return false;
NameSet columns;
for (const auto & it : block.getColumnsList())
columns.insert(it.name);
/// Составим выражение, вычисляющее выражения в WHERE и PREWHERE, зависящие только от имеющихся столбцов.
std::vector<ASTPtr> functions;
if (select.where_expression)
extractFunctions(select.where_expression, columns, functions);
if (select.prewhere_expression)
extractFunctions(select.prewhere_expression, columns, functions);
ASTPtr expression_ast = buildWhereExpression(functions);
if (!expression_ast)
return false;
/// Распарсим и вычислим выражение.
ExpressionAnalyzer analyzer(expression_ast, context, {}, block.getColumnsList());
ExpressionActionsPtr actions = analyzer.getActions(false);
actions->execute(block);
/// Отфильтруем блок.
String filter_column_name = expression_ast->getColumnName();
ColumnPtr filter_column = block.getByName(filter_column_name).column;
if (auto converted = filter_column->convertToFullColumnIfConst())
filter_column = converted;
const IColumn::Filter & filter = dynamic_cast<ColumnUInt8 &>(*filter_column).getData();
if (std::accumulate(filter.begin(), filter.end(), 0ul) == filter.size())
return false;
for (size_t i = 0; i < block.columns(); ++i)
{
ColumnPtr & column = block.safeGetByPosition(i).column;
column = column->filter(filter, -1);
}
return true;
}
bool filterBlockWithQuery(const ASTPtr & query, Block & block, const Context & context)
{
const ASTSelectQuery & select = typeid_cast<const ASTSelectQuery & >(*query);
if (!select.where_expression && !select.prewhere_expression)
return false;
NameSet columns;
for (const auto & it : block.getColumnsList())
columns.insert(it.name);
/// We will create an expression that evaluates the expressions in WHERE and PREWHERE, depending only on the existing columns.
std::vector<ASTPtr> functions;
if (select.where_expression)
extractFunctions(select.where_expression, columns, functions);
if (select.prewhere_expression)
extractFunctions(select.prewhere_expression, columns, functions);
ASTPtr expression_ast = buildWhereExpression(functions);
if (!expression_ast)
return false;
/// Let's parse and calculate the expression.
ExpressionAnalyzer analyzer(expression_ast, context, {}, block.getColumnsList());
ExpressionActionsPtr actions = analyzer.getActions(false);
actions->execute(block);
/// Filter the block.
String filter_column_name = expression_ast->getColumnName();
ColumnPtr filter_column = block.getByName(filter_column_name).column;
if (auto converted = filter_column->convertToFullColumnIfConst())
filter_column = converted;
const IColumn::Filter & filter = dynamic_cast<ColumnUInt8 &>(*filter_column).getData();
if (countBytesInFilter(filter) == 0)
return false;
for (size_t i = 0; i < block.columns(); ++i)
{
ColumnPtr & column = block.safeGetByPosition(i).column;
column = column->filter(filter, -1);
}
return true;
}
