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From "Durity, Sean R" <SEAN_R_DUR...@homedepot.com>
Subject RE: [EXTERNAL] Re: cold vs hot data
Date Tue, 18 Sep 2018 13:35:31 GMT
Wouldn’t you have the same problem with two similar tables with different primary keys (eg.,
UserByID and UserByName)? This is a very common pattern in Cassandra – inserting into multiple
tables… That’s what batches are for – atomicity.
I don’t understand the additional concern here.



Sean Durity

From: DuyHai Doan <doanduyhai@gmail.com>
Sent: Monday, September 17, 2018 4:23 PM
To: user <user@cassandra.apache.org>
Subject: Re: [EXTERNAL] Re: cold vs hot data

Sean

Without transactions à la SQL, how can you guarantee atomicity between both tables for upserts
? I mean, one write could succeed with hot table and fail for cold table

The only solution I see is using logged batch, with a huge overhead and perf hit on for the
writes

On Mon, Sep 17, 2018 at 8:28 PM, Durity, Sean R <SEAN_R_DURITY@homedepot.com<mailto:SEAN_R_DURITY@homedepot.com>>
wrote:
An idea:

On initial insert, insert into 2 tables:
Hot with short TTL
Cold/archive with a longer (or no) TTL
Then your hot data is always in the same table, but being expired. And you can access the
archive table only for the more rare circumstances. Then you could have the HOT table on a
different volume of faster storage. If the hot/cold tables are in different keyspaces, then
you could also have different replication (a HOT DC and an archive DC, for example)


Sean Durity


-----Original Message-----
From: Mateusz <mateusz-lists@ant.gliwice.pl<mailto:mateusz-lists@ant.gliwice.pl>>
Sent: Friday, September 14, 2018 2:40 AM
To: user@cassandra.apache.org<mailto:user@cassandra.apache.org>
Subject: [EXTERNAL] Re: cold vs hot data

On piątek, 14 września 2018 02:46:43 CEST Alaa Zubaidi (PDF) wrote:
> The data can grow to +100TB however the hot data will be in most cases
> less than 10TB but we still need to keep the rest of data accessible.
> Anyone has this problem?
> What is the best way to make the cluster more efficient?
> Is there a way to somehow automatically move the old data to different
> storage (rack, dc, etc)?
> Any ideas?

We solved it using lvmcache.

--
Mateusz
(...) mam brata - poważny, domator, liczykrupa, hipokryta, pobożniś,
krótko mówiąc - podpora społeczeństwa."
Nikos Kazantzakis - "Grek Zorba"




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