How to Get Timestamp from HBase Row or Column in Java

How can we retrieve the timestamp for a row or column in an HBase table?

I recently needed to obtain the time of insertion (or update) of a single row in HBase.

Suppose we’re running a scan on our table, and we’re now in charge of handling each result using our iterator.

Scan scan = new Scan();
try (ResultScanner scanner = hbaseTable.getScanner(scan)) {
  for (Result result = scanner.next(); result != null; result = scanner.next()) {
    // Do something with `result`
  }
} catch (IOException e) {
  e.printStackTrace();
}

Retrieve latest timestamp of row

If the timestamps for all cells in a row are the same, we can get the latest timestamp of the first column using rawCells().

long ts = result.rawCells()[0].getTimestamp()

From the HBase API documentation, rawCells() will return an array of type Cell that back this Result instance.

A cell in HBase is a single unit of storage, uniquely represented by row, column family, column qualifier, timestamp, and type.

For instance, a single column may be associated with multiple cells if that column was inserted then updated once (i.e. unique timestamps/versions).

If every column has multiple versions, the cells returned from rawCells() will be sorted with the newer timestamp first.

Retrieve latest timestamp of column

If we need the latest timestamp for a specific column, we can use getColumnLatestCell().

byte[] CF = Bytes.toBytes("column_family");
byte[] CQ = Bytes.toBytes("column_qualifier");
long ts = res.getColumnLatestCell(CF, CQ).getTimestamp();

From the HBase API documentation, getColumnLatestCell() will return the Cell with the most recent timestamp for a given column family and column qualifier.

Retrieve any timestamp of column

If we want access to all timestamps for a specific column, we can use getColumnCells().

byte[] CF = Bytes.toBytes("column_family");
byte[] CQ = Bytes.toBytes("column_qualifier");
List<Cell> cells = res.getColumnCells(CF, CQ);
int index = 1;
long ts = cells.get(index).getTimestamp();

From the HBase API documentation, getColumnCells() will return an array of type Cell.

The most recent timestamp will be at index 0 of this list.

The second, most recent timestamp will be at index 1, and so on.