incubator-cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Sylvain Lebresne <sylv...@datastax.com>
Subject Re: CQL update and TTL
Date Fri, 26 Apr 2013 15:57:12 GMT
> is there a way to either make TTL dynamic  (using ?)
>

Not at this time. There is
https://issues.apache.org/jira/browse/CASSANDRA-4450 open for that, but
that's not done yet.


> tell the engine not to cache the Prepared statement. I am using the new
> CQL Java Driver.
>

In that case, just don't use a prepared statement. Use a normal, non
prepared query. Yes, normal statements will be slightly slower, but if you
really have to update a column while preserving its TTL, as said above you
will have to do a read followed by a write, so the whole thing won't be
excessively efficient and hence I doubt not using prepared statements will
be the blocking part performance wise.

--
Sylvain



>
>
> Shahryar
>
>
> On Fri, Apr 26, 2013 at 11:42 AM, Sylvain Lebresne <sylvain@datastax.com>wrote:
>
>> This is indeed intended. That behavior is largely dictated by how the
>> storage engine works, and the fact that an update does no read internally
>> in particular.
>>
>> Yet, what I do not know is whether this behavior can be changed somehow
>>> to let the initial TTL,
>>>
>>
>> There's nothing like that supported, no. You have to read the value first
>> to get his TTL and then insert whatever update you want with the TTL you've
>> just fetch. And since we don't have a good way to do it much more
>> efficiently than server side, we prefer not doing it. That way the
>> performance impact is very explicit.
>>
>> --
>> Sylvain
>>
>>
>>
>>>
>>> Alain
>>>
>>>
>>> 2013/4/26 Shahryar Sedghi <shsedghi@gmail.com>
>>>
>>>> Apparently when I update a column using CQL that already has a TTL, it
>>>> resets the TTL to null, so if there was already a TTL for all columns that
>>>> I inserted part of a composite column set, this specific column that I
>>>> updated will not expire while the others are are getting expired. Is it how
>>>> it is expected to work or it is a bug?
>>>>
>>>> Thanks in advance
>>>>
>>>> Shahryar
>>>>
>>>>
>>>>
>>>
>>
>
>
> --
> "Life is what happens while you are making other plans." ~ John Lennon
>

Mime
View raw message