diff options
| -rw-r--r-- | sql/sql_window.cc | 76 |
1 files changed, 69 insertions, 7 deletions
diff --git a/sql/sql_window.cc b/sql/sql_window.cc index 8ec2b24d45d..5d929101e10 100644 --- a/sql/sql_window.cc +++ b/sql/sql_window.cc @@ -1891,7 +1891,15 @@ class Frame_positional_cursor : public Frame_cursor { public: Frame_positional_cursor(const Frame_cursor &position_cursor) : - position_cursor(position_cursor) {} + position_cursor(position_cursor), bound(NULL), offset(NULL), + negative_offset(false) {} + + Frame_positional_cursor(const Frame_cursor &position_cursor, + const Frame_cursor &bound, + Item &offset, + bool negative_offset) : + position_cursor(position_cursor), bound(&bound), offset(&offset), + negative_offset(negative_offset) {} void init(READ_RECORD *info) { @@ -1905,8 +1913,13 @@ class Frame_positional_cursor : public Frame_cursor void next_partition(ha_rows rownum) { - cursor.move_to(position_cursor.get_curr_rownum()); - add_value_to_items(); + ha_rows position= get_current_position(); + if (position_is_within_bounds(position)) + { + cursor.move_to(position); + cursor.fetch(); + add_value_to_items(); + } } void pre_next_row() @@ -1915,11 +1928,15 @@ class Frame_positional_cursor : public Frame_cursor void next_row() { - if (position_cursor.is_outside_computation_bounds()) + ha_rows position= get_current_position(); + if (!position_is_within_bounds(position)) clear_sum_functions(); - - cursor.move_to(position_cursor.get_curr_rownum()); - add_value_to_items(); + else + { + cursor.move_to(position_cursor.get_curr_rownum()); + cursor.fetch(); + add_value_to_items(); + } } ha_rows get_curr_rownum() const @@ -1928,8 +1945,53 @@ class Frame_positional_cursor : public Frame_cursor } private: + /* Check if a our position is within bounds. + * The position is passed as a parameter to avoid recalculating it. */ + bool position_is_within_bounds(ha_rows position) + { + if (!offset) + return !position_cursor.is_outside_computation_bounds(); + + /* No valid bound to compare to. */ + if (position_cursor.is_outside_computation_bounds() || + bound->is_outside_computation_bounds()) + return false; + + if (negative_offset) + { + if (position_cursor.get_curr_rownum() < position) + return false; /* Overflow below 0. */ + if (position < bound->get_curr_rownum()) /* We are over the bound. */ + return false; + } + else + { + if (position_cursor.get_curr_rownum() > position) + return false; /* Overflow over MAX_HA_ROWS. */ + if (position > bound->get_curr_rownum()) /* We are over the bound. */ + return false; + } + + return true; + } + + /* Get the current position, accounting for the offset value, if present. + NOTE: This function does not check over/underflow. + */ + ha_rows get_current_position() + { + ha_rows position = position_cursor.get_curr_rownum(); + if (offset) + position += offset->val_int() * (negative_offset ? -1 : 1); + return position; + } + const Frame_cursor &position_cursor; + const Frame_cursor *bound; + Item *offset; Table_read_cursor cursor; + + bool negative_offset; }; |