CQL for Cassandra 2.x

Determining the date/time of a write

A table contains a timestamp representing the date/time that a write occurred to a column. Using the WRITETIME function in a SELECT statement returns the date/time that the column was written to the database. The output of the function is microseconds except in the case of Cassandra 2.1 counter columns. Counter column writetime is milliseconds. This procedure continues the example from the previous procedure and calls the WRITETIME function to retrieve the date/time of the writes to the columns.

Procedure

  1. Insert more data into the table.
    INSERT INTO excelsior.clicks (
      userid, url, date, name)
      VALUES (
        cfd66ccc-d857-4e90-b1e5-df98a3d40cd6,
        'http://google.com',
        '2013-10-11', 'Bob'
    );
  2. Retrieve the date/time that the value Mary was written to the name column of the apache.org data. Use the WRITETIME function in a SELECT statement, followed by the name of a column in parentheses:
    SELECT WRITETIME (name) FROM excelsior.clicks
      WHERE url = 'http://apache.org' ALLOW FILTERING;
    The writetime output in microseconds converts to Sun, 14 Jul 2013 21:57:58 GMT or to 2:57 pm Pacific time.
    writetime(name)
    ------------------
    1373839078327001
  3. Retrieve the date/time of the last write to the date column for google.com data.
    SELECT WRITETIME (date) FROM excelsior.clicks
      WHERE url = 'http://google.com' ALLOW FILTERING;
    The writetime output in microseconds converts to Sun, 14 Jul 2013 22:03:15 GMT or 3:03 pm Pacific time.
    writetime(date)
    ------------------
    1373839395324001
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