Set TTL per column at insert time

[nilanjan sarkar]

Hi Guys,

I have a requirement, where i need to set TTL on only one column of a table.

What is the cql sematic for the particular insert statement?

Currently I see that the TTL on insert statement is only supported at row level, but not at a column level.

Thanks,

Nilanjan

[Kevin Gallardo]

Hi, 

TTL doesn't really work per row but more per column. Although while I think there is no syntax for specifying a TTL per column during an INSERT, you can do an UPDATE query on the desired column with a specified TTL, it would affect only the modified column. Here's an example:

cqlsh> create table ttltest(id int primary key, val text, val2 text);

cqlsh> insert into ttltest(id, val, val2) values (1, '1', '11');

cqlsh> select id, ttl(val), ttl(val2) from ttltest;

 id | ttl(val) | ttl(val2)

----+----------+-----------

  1 |     null |      null

(1 rows)

cqlsh> update ttltest using ttl 7000 set val = '1' where id = 1;

cqlsh> select id, ttl(val), ttl(val2) from ttltest;

 id | ttl(val) | ttl(val2)

----+----------+-----------

  1 |     6996 |      null

(1 rows)

Or do 2 inserts, one with the columns that don't need a TTL, and another one, on the same primary key that has the other column, with the TTL:

cqlsh> create table ttltest(id int primary key, val text, val2 text);

cqlsh> insert into ttltest(id, val) values (1, '1');

cqlsh> select id, ttl(val), ttl(val2) from ttltest;

 id | ttl(val) | ttl(val2)

----+----------+-----------

  1 |     null |      null

(1 rows)

cqlsh> insert into ttltest(id, val2) values (1, '11') using ttl 7000;

cqlsh> select id, ttl(val), ttl(val2) from ttltest;

 id | ttl(val) | ttl(val2)

----+----------+-----------

  1 |     null |      6995

(1 rows)

Hope that helps.

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Kévin Gallardo.

kgdo.me

Software Engineer in Drivers and Tools Team at DataStax.

 

[nilanjan sarkar]

Hi Kevin,

Thanks for your reply. That is how we are planning to do it :)

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