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From "Shawn Du" <shawn...@neulion.com.cn>
Subject 答复: how to use memory efficiently
Date Fri, 16 Dec 2016 00:55:20 GMT
Thanks.

I will test copyOnRead. In fact, we do have troubles in using ignite. For we
think it uses too much memory. We are finding ways to decrease the memory
consumption. 
I have an idea, but I don't know it is worthy of trying or not. Please
advise.

Suppose we have several tables. These tables store some metric data. Each
table row contains several dimensions data and metrics.
These table share some common dimensions. 

Currently, we store data like this, each table has all data. And when select
no need join:
dim_1, ...,dim_x, shared_dim_1,...,shared_dim_n, metric_1,...,metric_m

we are going to store like this, we use a separated table to store shared
dimensions data:
shared_id,shared_dim_1,...,shared_dim_n
and each table use a foreign key (shared_id)to refer to the shared table:
dim_1,...,dim_x, shared_id,metric_1,...,metric_m

This is common ways in RDBMS table design, I don't know whether it works on
ignite or not. 
Also I concern the big overhead each row entry will do can save the memory.

Thanks
Shawn

-----邮件原件-----
发件人: vdpyatkov [mailto:vldpyatkov@gmail.com] 
发送时间: 2016年12月15日 21:36
收件人: user@ignite.apache.org
主题: Re: how to use memory efficiently

Hi,

1) No cache name does not affect the memory utilization.
2) Yes, the key can
3) Ignite stores the description of the class only once, and organizes hash
each object. class or field name length does not affect the memory.
4) Off_heap may be cheaper by memory consume, because in some case two copy
of entries will stored on heap (on_heap - memory mode)[1]. But ONHEAP_TIERED
does not compress data.

If you do not going to modify data, which gets from cache, set copyOnRead
flag to false:

 <bean class="org.apache.ignite.configuration.CacheConfiguration">
        <property name="copyOnRead" value="false"/>

Also, you can try to compress data (before to will put it to cache), but
this restricts your SLQ.

[1]: https://issues.apache.org/jira/browse/IGNITE-2417 



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