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From Alain RODRIGUEZ <arodr...@gmail.com>
Subject Re: diff cassandra.yaml 1.2 --> 2.1
Date Mon, 29 Dec 2014 14:54:28 GMT
Thanks for the pointer Jason,

Yet, I thought that cache and memtables went off-heap only in version 2.1
and not 2.0 ("As of Cassandra 2.0, there are two major pieces of the
storage engine that still depend on the JVM heap: memtables and the key
cache." -->
http://www.datastax.com/dev/blog/off-heap-memtables-in-cassandra-2-1). So
this "clean up" makes sense to me but in the new 2.1 version of Cassandra.
I also read on the same blog that we might have the choice in/off heap for
memtables (or more precisely just get memtable buffers off-heap) . If this
is true, flush_largest_memtables_at still makes sense. About cache, isn't
key cache still in the heap, even in 2.1 ?

It looks like the removal of these option looks to me a bit radical and
premature. I guess I am missing something in my reasoning but can't figure
out what exactly.

C*heers,

Alain

2014-12-29 14:52 GMT+01:00 Jason Wee <peichieh@gmail.com>:

> https://issues.apache.org/jira/browse/CASSANDRA-3534
>
> On Mon, Dec 29, 2014 at 6:58 PM, Alain RODRIGUEZ <arodrime@gmail.com>
> wrote:
>
>> Hi guys,
>>
>> I am looking at added and dropped option in Cassandra between 1.2.18 and
>> 2.0.11 and this makes me wonder:
>>
>> Why has the index_interval option been removed from cassandra.yaml ? I
>> know we can also define it on a per table basis, yet, this global option
>> was quite useful to tune memory usage. I also know that this index is now
>> kept off-heap, but I can not see when and why this option has been removed,
>> any pointer ? Also it seems this option still usable even if not present by
>> default on cassandra.yaml, but it is marked as deprecated (
>> https://github.com/apache/cassandra/blob/cassandra-2.0.11/src/java/org/apache/cassandra/config/Config.java#L165).
>> Is this option deprecated on the table schema definition too ?
>>
>> Same kind of questions around the heap "emergency pressure valve" -->
>> "flush_largest_memtables_at", "reduce_cache_sizes_at" and
>> "reduce_cache_capacity_to", except that those params seems to have been
>> dropped directly. Why, is there no more need of it, has some other
>> mechanism replaced it, improving things ?
>>
>> Hope this wasn't already discussed,I was unable to find information about
>> it anyway.
>>
>> C*heers !
>>
>
>

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