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From "Sylvain Lebresne (JIRA)" <j...@apache.org>
Subject [jira] [Resolved] (CASSANDRA-4963) A cql collection 'column' doesn't own it's ttl
Date Wed, 14 Nov 2012 09:58:12 GMT

     [ https://issues.apache.org/jira/browse/CASSANDRA-4963?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Sylvain Lebresne resolved CASSANDRA-4963.
-----------------------------------------

    Resolution: Not A Problem

This works as designed. When a TTL is used in a statement, it only applies to the _values_
that this statement updates/inserts.

For the record, I'm not contesting that "a collection only ever have a TTL as a whole and
if a statement with a TTL updates/inserts a collection, it sets that collection TTL" wouldn't
be a valid alternative semantic (at least on paper), but I do pretend that the current semantic
is superior in practice because:
# It's more generic/flexible. You can implement the 'the collection has a TTL as a whole'
semantic using the current one client side (at least you can implement it as well as we could
internally). The reverse is not true.
# Implementing that latter semantic would require us to do a read before we write (even when
no ttl is used because you'd always have to know if the collection already exists with a ttl,
which is a no go in itself) and to have some distributed locking (or at least I don't see
how we could guarantee otherwise that all the internal columns composing the collection always
have the same TTL).

                
> A cql collection 'column' doesn't own it's ttl
> ----------------------------------------------
>
>                 Key: CASSANDRA-4963
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-4963
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>    Affects Versions: 1.2.0 beta 2
>            Reporter: Dave Brosius
>            Priority: Minor
>
> if you add a collection column with a ttl, then later update the collection by adding
a new element, the 'under the covers' column representing the added value has no ttl. It seems
like ttl tombstoning should only be allowed to remove the collection in entirety, or not touch
it, but not be allowed to modify it by removing parts.
> example
> cqlsh> create keyspace collections with replication = {'class':'SimpleStrategy', 'replication_factor':1};
> cqlsh> use collections;
> cqlsh:collections> create table collections (key int primary key, aset set<text>);
> cqlsh:collections> insert into collections (key, aset) values (1, {'fee', 'fi'}) using
ttl 10000;
> cqlsh:collections> update collections set aset = aset + {'fo', 'fum'} where key =
1;
> cqlsh:collections> exit
> cassandra-cli
> [default@unknown] use collections
> [default@collections] get collections[1];
> => (column=, value=, timestamp=1352874321877000)
> => (column=aset:666565, value=, timestamp=1352874314717000, ttl=10000)
> => (column=aset:6669, value=, timestamp=1352874314717000, ttl=10000)
> => (column=aset:666f, value=, timestamp=1352874321877000)
> => (column=aset:66756d, value=, timestamp=1352874321877000)

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