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From Vladimir Rodionov <vrodio...@carrieriq.com>
Subject RE: one column family but lots of tables
Date Thu, 22 Aug 2013 21:16:50 GMT
Yes, number of tables must be reasonable as well. Region Servers operates on 'regions' .
Each Table can have multiple CFs, each CF can have multiple regions. The more regions you
have per Region Server -
the more data you will need to keep in memory, the more time it will take to recover  from
Region Server failure, therefore 
there is a practical limit on number of regions per one Region Server (hundreds - not thousands).
It is recommended
to keep the number of regions per server much less than 1000 (say , 100- 500 max). 

Best regards,
Vladimir Rodionov
Principal Platform Engineer
Carrier IQ, www.carrieriq.com
e-mail: vrodionov@carrieriq.com

From: Koert Kuipers [koert@tresata.com]
Sent: Thursday, August 22, 2013 12:30 PM
To: user@hbase.apache.org; Vladimir Rodionov
Subject: Re: one column family but lots of tables

if that is the case, how come people keep warning about limiting the number of column families
to only a handful (with more hbase performance will degrade supposedly), yet there seems to
be no similar warnings for number of tables? see for example here:

if a table means at least one column family then the number of tables should also be kept
to a minumum, no?

On Thu, Aug 22, 2013 at 1:58 PM, Vladimir Rodionov <vrodionov@carrieriq.com<mailto:vrodionov@carrieriq.com>>
Nope. Column family is per table (its sub-directory inside your table directory in HDFS).
If you have N tables you will always have , at least, N distinct CFs (even if they have the
same name).

Best regards,
Vladimir Rodionov
Principal Platform Engineer
Carrier IQ, www.carrieriq.com<http://www.carrieriq.com>
e-mail: vrodionov@carrieriq.com<mailto:vrodionov@carrieriq.com>

From: Koert Kuipers [koert@tresata.com<mailto:koert@tresata.com>]
Sent: Thursday, August 22, 2013 8:06 AM
To: user@hbase.apache.org<mailto:user@hbase.apache.org>
Subject: one column family but lots of tables

i read in multiple places that i should try to limit the number of column
families in hbase.

do i understand it correctly that when i create lots of tables, but they
all use the same column family (by name), that i am just using one column
family and i am OK with respect to limiting number of column families ?

thanks! koert

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