Cassandra + SpringBoot: Configure Table to automatically add INSERT timestamp

Question

Small question regarding Cassandra, with the context of a SpringBoot application please.

I am interested in adding onto the table the timestamp of when a row gets inserted onto the table.

Therefore, when creating the table, I do this:

create table mytable (someprimarykey text PRIMARY KEY, timestamp long, someotherfield text);

I can see a column timestamp, happy.

Then, the web application:

@Table
public class MyTable {

    @PrimaryKey
    private final String somePrimaryKey;

    private final long timestamp;

    private final String someOtherField;

//constructor + getters + setters

And when I insert, I will do the usual:

MyTable myTable = new MyTable(somePK, System.currentTimeMillis(), "foo");
myTableRepository.save(myTable);

This works fine, I can see in the table my record, with the time of the insert, happy.

Problem: Now, for the hundreds of POJOs I am interested to insert into Cassandra, all of them are carrying this timestamp long field. Somehow, on the web application layer, I am dealing with a database concept, the timestamp of the write.

Question: May I ask if it is possible to delegate this back to the database? Some kind of:

create table mytable (someprimarykey text PRIMARY KEY, hey-cassandra-please-automatically-add-the-time-when-this-row-is-written long, someotherfield text);
or
create table mytable (someprimarykey text PRIMARY KEY, someotherfield text WITH default timestamp-insert-time-column);

And the web app can have the abstraction creating and inserting POJOs without carrying this timestamp field?

Thank you

Erick Ramirez · Accepted Answer · 2022-04-20 02:57:39Z

1

It isn't necessary to store the insert time of each row separately since Cassandra already stores this for all writes in the metadata.

There is a built-in CQL function WRITETIME() which returns the date/time (encoded in microseconds) when a column was written to the database.

In your case, you can query your table with:

SELECT WRITETIME(someotherfield) FROM mytable WHERE someprimarykey = ?

For details, see the CQL doc on retrieving the write time. Cheers!

answered Apr 20, 2022 at 2:57

Erick Ramirez

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