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: vrodio...@carrieriq.com ________________________________________ From: Koert Kuipers [ko...@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: http://comments.gmane.org/gmane.comp.java.hadoop.hbase.user/27616 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 <vrodio...@carrieriq.com<mailto:vrodio...@carrieriq.com>> wrote: 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: vrodio...@carrieriq.com<mailto:vrodio...@carrieriq.com> ________________________________________ From: Koert Kuipers [ko...@tresata.com<mailto:ko...@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 Confidentiality Notice: The information contained in this message, including any attachments hereto, may be confidential and is intended to be read only by the individual or entity to whom this message is addressed. If the reader of this message is not the intended recipient or an agent or designee of the intended recipient, please note that any review, use, disclosure or distribution of this message or its attachments, in any form, is strictly prohibited. If you have received this message in error, please immediately notify the sender and/or notificati...@carrieriq.com<mailto:notificati...@carrieriq.com> and delete or destroy any copy of this message and its attachments.
