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Posted to user@cassandra.apache.org by Christopher Wirt <ch...@struq.com> on 2013/09/18 16:29:50 UTC
TTL and gc_grace_Seconds
I have a column family contains time series events, all columns have a 24
hour TTL and gc_grace_seconds is currently 20 days. There is a TimeUUID in
part of the key.
It takes 15 days to repair the entire ring.
Consistency is not my main worry. Speed is. We currently write to this CF at
LOCAL_QUORUM and read at ONE.
Is there any reason to have gc_grace_seconds higher than the TTL? Feels like
I'm just wasting resources all over given my consistency and speed
requirements.
Second question.
Does anyone vary their read repair ratio throughout the day.. i.e. at peak
turn off read repairs, turn to 0.7 for the grave yard shift.
Cheers,
Chris
Re: TTL and gc_grace_Seconds
Posted by sankalp kohli <ko...@gmail.com>.
You might want to do some stuff in the application layer. If you can deal
with deleted deletes in the application layer, you can reduce your gc-grace
period.
On Wed, Sep 18, 2013 at 7:42 AM, horschi <ho...@gmail.com> wrote:
> Hi Christopher,
>
> in 2.0 gc_grace should be capped by TTL anyway: see CASSANDRA-4917
>
> cheers,
> Christian
>
>
>
> On Wed, Sep 18, 2013 at 4:29 PM, Christopher Wirt <ch...@struq.com>wrote:
>
>> I have a column family contains time series events, all columns have a 24
>> hour TTL and gc_grace_seconds is currently 20 days. There is a TimeUUID in
>> part of the key.****
>>
>> ** **
>>
>> It takes 15 days to repair the entire ring.****
>>
>> ** **
>>
>> Consistency is not my main worry. Speed is. We currently write to this CF
>> at LOCAL_QUORUM and read at ONE.****
>>
>> ** **
>>
>> Is there any reason to have gc_grace_seconds higher than the TTL? Feels
>> like I’m just wasting resources all over given my consistency and speed
>> requirements. ****
>>
>> ** **
>>
>> ** **
>>
>> Second question.****
>>
>> Does anyone vary their read repair ratio throughout the day.. i.e. at
>> peak turn off read repairs, turn to 0.7 for the grave yard shift.****
>>
>> ** **
>>
>> ** **
>>
>> Cheers,****
>>
>> Chris****
>>
>
>
Re: TTL and gc_grace_Seconds
Posted by horschi <ho...@gmail.com>.
Hi Christopher,
in 2.0 gc_grace should be capped by TTL anyway: see CASSANDRA-4917
cheers,
Christian
On Wed, Sep 18, 2013 at 4:29 PM, Christopher Wirt <ch...@struq.com>wrote:
> I have a column family contains time series events, all columns have a 24
> hour TTL and gc_grace_seconds is currently 20 days. There is a TimeUUID in
> part of the key.****
>
> ** **
>
> It takes 15 days to repair the entire ring.****
>
> ** **
>
> Consistency is not my main worry. Speed is. We currently write to this CF
> at LOCAL_QUORUM and read at ONE.****
>
> ** **
>
> Is there any reason to have gc_grace_seconds higher than the TTL? Feels
> like I’m just wasting resources all over given my consistency and speed
> requirements. ****
>
> ** **
>
> ** **
>
> Second question.****
>
> Does anyone vary their read repair ratio throughout the day.. i.e. at peak
> turn off read repairs, turn to 0.7 for the grave yard shift.****
>
> ** **
>
> ** **
>
> Cheers,****
>
> Chris****
>