In Cassandra, every table has a timestamp value that contains the Epoch timestamp that a given write operation was executed on a column.
In this tutorial, we will show you how to use the writeTime() function to fetch the timestamp that a specific column was inserted into a table.”
Sample Table and Records
Let us take the statements below that creates a table and insert sample records into a given table.
id int,
product_name text,
price int,
qty int,
primary key(id)
);
begin batch
insert into products(id, product_name, price, qty)
values (1, 'product_1', 100, 5640);
insert into products(id, product_name, price, qty)
values (2, 'product_2', 800, 550);
insert into products(id, product_name, price, qty)
values (3, 'product_3', 500, 5550);
insert into products(id, product_name, price, qty)
values (4, 'product_3', 150, 540);
insert into products(id, product_name, price, qty)
values (5, 'product_4', 160, 260);
insert into products(id, product_name, price, qty)
values (6, 'product_5', 130, 5640);
apply batch;
in the example above, we use batch processing to insert multiple records into the table. Although you can specify which statement the server should allocate a timestamp, we simply left it out.
You can learn more about Cassandra batch processing in our tutorial on the topic.
Cassandra Fetch Write Timestamp
To fetch the timestamp that the value “product_4” was added into the product_name column, we can run the query as shown:
This should return the timestamp for the specified write as shown:
-------------------------
1664055523819399
(1 rows)
The above resolves to the human time as:
Conclusion
In this post, we discussed using the writeTime() function to fetch the timestamp at which a specific write occurred in a table.
Thanks for reading & catch you in the next one.
