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: [EMAIL PROTECTED]> To:
[email protected]> > 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 <[EMAIL PROTECTED]>> Sent: Wednesday, November 7, 2007
1:03pm> To: [email protected] <[email protected]>>
Subject: RE: HBase num_versions> > num_versions=all ?> > ---> Jim Kellerman,
Senior Engineer; Powerset> [EMAIL PROTECTED]> > > > -----Original Message----->
> From: Michael Stack [mailto:[EMAIL PROTECTED]> > Sent: Wednesday, November
07, 2007 9:59 AM> > To: [email protected]> > Cc: [EMAIL PROTECTED]>
> 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 [EMAIL PROTECTED]> > >> > >> > >> > >> -----Original
Message-----> > >> From: Stu Hood [mailto:[EMAIL PROTECTED]> > >> Sent:
Tuesday, November 06, 2007 11:23 PM> > >> To: [email protected]> >
>> 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)> > >>> > >>> > >>> >> >> >
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