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https://issues.apache.org/jira/browse/CASSANDRA-2620?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13030861#comment-13030861
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Stu Hood commented on CASSANDRA-2620:
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bq. Right now, if you need to know when a column c will expire, you'll compute
c.timestamp + c.ttl. That code will break if you change the meaning of the ttl
field.
Correct, but there is a _super_ easy alternative... if we return the delta TTL
to the user instead, they can figure out when something will expire by adding
the delta TTL to their local time. N seconds passed on the server, and most
likely something around N seconds passed on the client.
IMO the implementation is wasteful, and the client API behavior isn't worth
preserving.
> Don't persist TTL for expiring columns
> --------------------------------------
>
> Key: CASSANDRA-2620
> URL: https://issues.apache.org/jira/browse/CASSANDRA-2620
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Stu Hood
> Priority: Minor
>
> We persist both the TTL (5 seconds from now) and the localExpirationTime (the
> local time at +5 seconds) for expiring columns, but the TTL is never used
> again, except when we return expiring columns to clients.
> Rather than storing the TTL to return to clients, we could calculate a delta
> TTL value by subtracting the current time from the localExpirationTime, and
> save 4 bytes on disk.
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