Function filterBlockWithQuery

src/Storages/VirtualColumnUtils.cpp:235–279

}

void filterBlockWithQuery(const ASTPtr & query, Block & block, ContextPtr context, ASTPtr expression_ast, ASTPtr partition_filter)
{
    if (block.rows() == 0)
        return;

    if (!expression_ast)
        prepareFilterBlockWithQuery(query, context, block, expression_ast, partition_filter);

    if (!expression_ast)
        return;

    /// Let's analyze and calculate the prepared expression.
    auto syntax_result = TreeRewriter(context).analyze(expression_ast, block.getNamesAndTypesList());
    ExpressionAnalyzer analyzer(expression_ast, syntax_result, context);
    buildSets(expression_ast, analyzer);
    ExpressionActionsPtr actions = analyzer.getActions(false /* add alises */, true /* project result */, CompileExpressions::yes);

    Block block_with_filter = block;
    actions->execute(block_with_filter);

    /// Filter the block.
    String filter_column_name = expression_ast->getColumnName();
    ColumnPtr filter_column = block_with_filter.getByName(filter_column_name).column->convertToFullColumnIfConst();

    ConstantFilterDescription constant_filter(*filter_column);

    if (constant_filter.always_true)
    {
        return;
    }

    if (constant_filter.always_false)
    {
        block = block.cloneEmpty();
        return;
    }

    FilterDescription filter(*filter_column);

    for (size_t i = 0; i < block.columns(); ++i)
    {
        ColumnPtr & column = block.safeGetByPosition(i).column;
        column = column->filter(*filter.data, -1);
    }
}

void cascadingDrop(const StorageID & table_id, const ASTPtr & partition_or_predicate,
                   bool drop_where, bool detach, bool cascading, ContextPtr context)