cassandra fn – writetime

cassandra – Determining the date/time of a write

corerootz - Ravi Kiran Krovvidi NoSQL - Cassandra, HBase

Using the WRITETIME function in a SELECT statement returns the date/time in microseconds that the column was written to the database. 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