MapR 5.0 Documentation : Delete a specific version of a column in the row that was fetched

APIs used

The APIs that are used are defined in the header file mutations.h.

  • hb_delete_add_column(): Set the column criteria for hb_delete_t object. Set the qualifier to NULL to delete all columns of a family. Only the cells with timestamp less than or equal to the specified timestamp are deleted. Set the timestamp to INT64_MAX to delete all versions of the column. This API is optional for deletes.
  • hb_delete_create(): Creates a structure for delete operation and return its handle.
  • hb_mutation_set_table(): Sets the table name for the mutation.
  • hb_mutation_send(): Queues the put operation for sending to the server. Mutations are not performed atomically and can be batched in a non-deterministic way on either the client side or the server side. Any buffer attached to a mutation object (put or delete) must not be altered until the callback has been received.

Sequence of steps

  1. Create a delete object for a row with a particular row key.
  2. Add a column to the delete object.
  3. Specify the name of the table from which to delete the cell version.
  4. Queue the delete.
  5. Wait three seconds for the delete to be flushed, then wait for the RPC call to complete.

Code

  // delete a specific version of a column
  {
    bytebuffer rowKey = bytebuffer_strcpy("row_with_two_cells");
    hb_delete_t del = NULL;
    hb_delete_create(rowKey->buffer, rowKey->length, &del);
    hb_delete_add_column(del, FAMILIES[0], 1,
        column_a->buffer, column_a->length, 1391111111112L);
    hb_mutation_set_table(del, table_name, table_name_len);
    delete_done = false;
    hb_mutation_send(client, del, delete_callback, rowKey);
    wait_for_delete();
  }