hbase-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Jahangir Mohammed <md.jahangi...@gmail.com>
Subject Re: No. of families
Date Thu, 29 Dec 2011 05:19:33 GMT
Generally, low number of C.F.s is better. Lower the number of C.F.s, better
the performance. I am not sure if users go above 8 C.F.s. Most of the users
keep number of C.F.s less than 4 or so. The implication of having more
C.F.s and the density of those C.F.s in terms of data may vary, in that
case it can cause unnecessary I/O burden when flushing or compacting.

Below link should help too:
http://hbase.apache.org/book/number.of.cfs.html

Setting compaction per C.F. is WIP
https://issues.apache.org/jira/browse/HBASE-4770

Thanks,
Jahangir.

On Thu, Dec 29, 2011 at 12:01 AM, Rohit Kelkar <rohitkelkar@gmail.com>wrote:

> When we say less column families, how much is less? Is this guided by
> a ratio of the number of rows stored in the Htable to number of column
> families. Or number of tables to number of column families. If I
> understand correctly, the content of each column family is stored in a
> separate file. So does it have anything to do with the disk space
> allocated to hadoop?
>
> - Rohit Kelkar
>
> On Wed, Dec 28, 2011 at 10:14 PM, Mohammad Tariq <dontariq@gmail.com>
> wrote:
> > Hi Doug,
> >
> >  Thanks a lot for the reply.Ya, I had asked a similar
> > question.Actually I am stuck with some schema design issue.I am sorry,
> > the intention was not to ask the same thing repeatedly.I'll try to
> > figure it out with the help of guidelines provided.Many thanks.
> >
> > Regards,
> >     Mohammad Tariq
> >
> >
> >
> > On Wed, Dec 28, 2011 at 7:24 PM, Doug Meil
> > <doug.meil@explorysmedical.com> wrote:
> >>
> >> Hi there-
> >>
> >> re:  "number of CF's"
> >>
> >> Yes.  Fewer is better.
> >>
> >> http://hbase.apache.org/book.html#schema
> >>
> >> re:  "sub column families"
> >>
> >>
> >> There aren't "sub column families" - it's just columns (within a CF).
> >>
> >> http://hbase.apache.org/book.html#datamodel
> >>
> >>
> >> If I am not mistaken you asked a similar question to the dist-list a few
> >> weeks ago. The answers haven't changed.
> >>
> >>
> >>
> >>
> >>
> >>
> >> On 12/28/11 2:53 AM, "Mohammad Tariq" <dontariq@gmail.com> wrote:
> >>
> >>>Hello all,
> >>>
> >>>    Having less no. of column families is advisable. It is feasible to
> >>>have 2 or 3 sub column families within a single column family???I
> >>>want to store xml data in Hbase and I have sub tags that may go down
> >>>to 2 or 3 levels.
> >>>
> >>>Regards,
> >>>    Mohammad Tariq
> >>>
> >>
> >>
>

Mime
  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message