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Date: Fri, 13 Aug 2010 11:38:31 -0700
Message-ID: <AANLkTinYrsGKZDh+Y2Z1YOf_TX6WG+1srhA3McYcAh-+@mail.gmail.com>
Subject: Re: Questions from a friend that I didn't feel comfortable
 answering...
From: Ryan Rawson <ryanobjc@gmail.com>
To: user@hbase.apache.org
Cc: hbase-user@hadoop.apache.org
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Here are some answers:

On Fri, Aug 13, 2010 at 11:28 AM, Michael Segel
<michael_segel@hotmail.com> wrote:
>
>
>
> Hi,
> A fellow co-worker was asking some questions and while I thought I might =
know the answer I wasn't 100% sure that I was right.
> So I figure its better to be safe than sorry, and forward the questions o=
ut to the list because I know that there are a couple of wonks who know thi=
s stuff off the top of their head. :-)(Also its a great way to get the corr=
ect answer documented so others can hit Google/Yahoo/<insert your favorite =
search engine> and find a response.)
> Here are the questions:
>
> 1.
> Where is filtering happening?
> Is it on the client or at the read time?

Server side.

>
> 2.
> In the result
> scanner, when are records delivered to the client? =A0When I do next? In
> other words what is the penalty for having scan wider than the actual dat=
a that
> I need

Records are read at 'next' time.  The penalty of having a wider scan
is you read more data than necessary which increases client<->RS rpc
bandwidth and latency.

>
> 3.
> Where can I find the
> example of custom WritableByteArrayComparable and Comparator? How do I de=
cide
> which one to overwrite?

I don't understand this question in the context of HBase - you don't
get the ability to choose a comparator for a table.  This is because
rows from tables end up in META and thus you'd have to have multiple
comparators in meta depending on which part of the table we'd be at.
(ouch!)


>
> IMHO I think #3 is a good thing to get documented.
> Thinking of a spatial query where you want to find all of the data from p=
oints within a given volume... It would make life easier.
> TIA!
> -Mike
>
>
>