| 40 | } |
| 41 | |
| 42 | Block LimitBlockInputStream::readImpl() |
| 43 | { |
| 44 | Block res; |
| 45 | UInt64 rows = 0; |
| 46 | |
| 47 | /// pos >= offset + limit and all rows in the end of previous block were equal |
| 48 | /// to row at 'limit' position. So we check current block. |
| 49 | if (!ties_row_ref.empty() && pos >= offset + limit) |
| 50 | { |
| 51 | res = children.back()->read(); |
| 52 | rows = res.rows(); |
| 53 | |
| 54 | if (!res) |
| 55 | return res; |
| 56 | |
| 57 | SharedBlockPtr ptr = new detail::SharedBlock(std::move(res)); |
| 58 | ptr->sort_columns = extractSortColumns(*ptr, description); |
| 59 | |
| 60 | UInt64 len; |
| 61 | for (len = 0; len < rows; ++len) |
| 62 | { |
| 63 | SharedBlockRowRef current_row; |
| 64 | current_row.set(ptr, &ptr->sort_columns, len); |
| 65 | |
| 66 | if (current_row != ties_row_ref) |
| 67 | { |
| 68 | ties_row_ref.reset(); |
| 69 | break; |
| 70 | } |
| 71 | } |
| 72 | |
| 73 | if (len < rows) |
| 74 | { |
| 75 | for (size_t i = 0; i < ptr->columns(); ++i) |
| 76 | ptr->safeGetByPosition(i).column = ptr->safeGetByPosition(i).column->cut(0, len); |
| 77 | } |
| 78 | |
| 79 | return *ptr; |
| 80 | } |
| 81 | |
| 82 | if (pos >= offset + limit) |
| 83 | { |
| 84 | if (!always_read_till_end) |
| 85 | return res; |
| 86 | else |
| 87 | { |
| 88 | while (children.back()->read()) |
| 89 | ; |
| 90 | return res; |
| 91 | } |
| 92 | } |
| 93 | |
| 94 | do |
| 95 | { |
| 96 | res = children.back()->read(); |
| 97 | if (!res) |
| 98 | return res; |
| 99 | rows = res.rows(); |