hadoop-common-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From edward yoon <webmas...@udanax.org>
Subject RE: HBase num_versions
Date Wed, 07 Nov 2007 23:27:29 GMT

Yeah, Thanks stu hood.
Time-dimension is one of the most important things.Also, It's a matter of considerable complexity.
 
And last, Hbase's Time-dimension is different from date field in traditional-db (or hbase).
I will clarify it. 
 
Now "select statement" isn't perfect yet. 
(A little imitation is a dangerous thing.)
 
Thanks,
Edward.
------------------------------
B. Regards,
Edward yoon @ NHN, corp. 
Home : http://www.udanax.org> Date: Wed, 7 Nov 2007 14:45:39 -0500> Subject: RE: HBase
num_versions> From: stuhood@webmail.us> To: hadoop-user@lucene.apache.org> > Currently
in the shell, num_versions = 0 is equivalent to 'all versions'.> > I don't think that
needs to be changed, unless someone can imagine a clause on a query that wouldn't require
a version of a row to operate correctly.> > Thanks,> Stu> > > -----Original
Message-----> From: Jim Kellerman <jim@powerset.com>> Sent: Wednesday, November
7, 2007 1:03pm> To: hadoop-user@lucene.apache.org <hadoop-user@lucene.apache.org>>
Subject: RE: HBase num_versions> > num_versions=all ?> > ---> Jim Kellerman,
Senior Engineer; Powerset> jim@powerset.com> > > > -----Original Message----->
> From: Michael Stack [mailto:stack@duboce.net]> > Sent: Wednesday, November 07,
2007 9:59 AM> > To: hadoop-user@lucene.apache.org> > Cc: stuhood@webmail.us>
> Subject: Re: HBase num_versions> >> > In the absence of a num_versions qualifier,
shell makes> > presumption that you want ALL versions. Changing the default> >
to be 1 would mean that we would have to add some other means> > of specifying all versions
("num_versions=-1" or some such> > oddity). What ye think?> > St.Ack> >>
>> > Jim Kellerman wrote:> > > Yes, for num_versions > 1, HBase has to
dig through the> > memcache, and multiple HStore files until it has found the> >
requested number of versions or runs out of places to look.> > This is especially apparent
if there is only 1 version. It> > has to do a lot of work for nothing.> > >>
> > Please enter a Jira for the HBase shell to default the> > number of versions
to 1.> > >> > > ---> > > Jim Kellerman, Senior Engineer; Powerset
jim@powerset.com> > >> > >> > >> > >> -----Original
Message-----> > >> From: Stu Hood [mailto:stuhood@webmail.us]> > >>
Sent: Tuesday, November 06, 2007 11:23 PM> > >> To: hadoop-user@lucene.apache.org>
> >> Subject: HBase num_versions> > >>> > >> Hey guys,>
> >>> > >> Just noticed some surprising behavior for select statements>
> >> in HBase 0.15: a select command without a num_versions = 1> > >>
clause takes 2 orders of magnitude longer to run than a> > bare select.> > >>>
> >> Is this inconsistent implementation, or is it taking extra> > >>
time to scan for additional versions? If this isn't a bug,> > >> then perhaps
the default for num_versions should be 1 to keep> > >> things snappy by default.>
> >>> > >> ============================================================>
> >>> > >> Hbase> describe test;> > >> +------------------------------------------------------------->
> >> ----------------+> > >> | Column Family Descriptor> > >>
|> > >> +-------------------------------------------------------------> >
>> ----------------+> > >> | name: hex, max versions: 3, compression: NONE,
in memory:> > >> false, max length:|> > >> | 2147483647, bloom filter:
none> > >> |> > >> +------------------------------------------------------------->
> >> ----------------+> > >> 1 columnfamily(s) in set (0.310 sec)>
> >> Hbase> select hex: from test where row = '3980000'> > num_versions
= 1;> > >> 3cbae0> > >> 1 row(s) in set (0.016 sec)> > >>
Hbase> select hex: from test where row = '3980000';> > >> 3cbae0> > >>
1 row(s) in set (1.882 sec)> > >>> > >> ============================================================>
> >>> > >>> > >> Thanks,> > >>> > >>>
> >> Stu Hood> > >> Webmail.us> > >> "You manage your business.
We'll manage your email."(r)> > >>> > >>> > >>> >>
>> > 
_________________________________________________________________
Help yourself to FREE treats served up daily at the Messenger Café. Stop by today.
http://www.cafemessenger.com/info/info_sweetstuff2.html?ocid=TXT_TAGLM_OctWLtagline
Mime
  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message