APIs used

  • hb_get_add_column(): Adds a column family and optionally a column qualifier to an hb_get_t object.
  • hb_get_create(): Creates an hb_get_t object and populates the handle get_ptr.
  • hb_get_send()Queues the get request. The callback specified by cb is called on completion. Any buffers attached to the get object can be reclaimed only after the callback is received.
  • hb_get_set_num_versions()Sets maximum number of latest values of each column to be fetched. This API is optional.
  • hb_get_set_table(): Sets the name of the table to get data from.

Sequence of steps

  1. Create a row object named rowKey.
  2. Create a get object.
  3. Specify the column families and optional column qualifiers to get values from.
  4. Specify the name of the table.
  5. Specify the number of versions of the column values to get.
  6. Queue the get request.
  7. Wait for the get to complete.

Code

  // fetch a row with row-key="row_with_two_cells"
  {
    bytebuffer rowKey = bytebuffer_strcpy("row_with_two_cells");
    hb_get_t get = NULL;
    hb_get_create(rowKey->buffer, rowKey->length, &get);
    hb_get_add_column(get, FAMILIES[0], 1, NULL, 0);
    hb_get_add_column(get, FAMILIES[1], 1, NULL, 0);
    hb_get_set_table(get, table_name, table_name_len);
    hb_get_set_num_versions(get, 10); // up to ten versions of each column
    get_done = false;
    hb_get_send(client, get, get_callback, rowKey);
    wait_for_get();
  }