WHICH is BETTER > Triggers or TTL [closed] - cassandra

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I need to know which one is better for performance
TRIGGERS || TTL ?
Or which among st them are more convenient to use.

Answer 1

So while "better" is definitely subjective, what I'll do here is talk about what you need to do to enable both a TTL and a trigger in Cassandra. Then you can decide for yourself.
To implement a TTL, you need to modify the default_time_to_live property on your table to a value (in seconds) starting from write-time to when that data should be deleted. It defaults to zero (0), which effectively disables TTL for that table. The following CQL will set a TTL of 7 days:
ALTER TABLE my_keyspace_name.my_table_name WITH default_time_to_live = 604800;
Do note that TTL'd data still creates tombstones, so be careful of that. It works best for time series use cases, where data is clustered by a timestamp/timeUUID in DESCending order. The descending order part is key, as that keeps your tombstones at the "bottom" of the partition, so queries for recent data should never encounter them.
Implementing a trigger is somewhat more complex. For starters, you'll need to write a class which implements the ITrigger interface. That class will also need to overload the augment method, like this:
public class MyTrigger implements ITrigger {
public Collection<RowMutation> augment(ByteBuffer key, ColumnFamily update)
Inside that method, you'll want to grab the table and keyspace names from the update metadata, build your DELETE statement:
{
String keyspace = update.metadata().ksName;
String table = update.metadata().cfName;
StringBuilder strCQLHeader = new StringBuilder("DELETE FROM ")
.append(keyspace)
.append(".")
.append(table)
.append(" WHERE ");
...As well as some logic to grab the key values to delete/move and anything else you'd need to do here.
Next, you'll need to build that class into a JAR and copy it to the $CASSANDRA_HOME/lib/triggers/ dir.
Then (yep, not done yet) you'll need to add that trigger class to your table:
CREATE TRIGGER myTrigger ON my_table_name USING 'com.yourcompany.packagename.MyTrigger';
While you're free to choose whichever works best for you, I highly recommend using a TTL. Implementing triggers in Cassandra is one of those things that tends to be on a "crazy" level of difficulty.