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HBase, mail # user - Temporal in Hbase?


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RE: Temporal in Hbase?
Ramkrishna.S.Vasudevan 2012-10-11, 05:32
Oops!! Anoop has just replied the same similar to mine :)

Regards
Ram

> -----Original Message-----
> From: Anoop Sam John [mailto:[EMAIL PROTECTED]]
> Sent: Thursday, October 11, 2012 10:40 AM
> To: [EMAIL PROTECTED]
> Subject: RE: Temporal in Hbase?
>
> Hi Shumin,
>
> >start_time < const_et and end_time >= const_st or end_time is null.
> Your problem was end_time >= const_st or end_time is null.....
>
> You can make use of FilterList with MUST_PASS_ALL (AND) condition
> only.. This can contain one SingleColumnValueFilter correspodning to
> start_time with your condition and value.  "end_time" is null means you
> are not having any KV added in the row for this column? [This column
> value is missing for a row] In that case you can use a
> SingleColumnValueFilter with condition and value "const_st"  and to
> this filter set  filterIfMissing(false). This means if the column is
> absent for a row, that row wont get filtered out.. This is what you
> want right? [But the default value for filterIfMissing is false only ]
>
> FYI a FilterList can contain another filter list
> So if you have a query like  col1=? AND ( col2=? OR col2=? ) you can
> use FilterList.. One inner filter list with MUST_PASS_ONE for col2 and
> an outer FL with MUST_PASS_ALL which contains the inner FL and SCVF for
> col1..    Hope I understood your problem and giving the answer which
> you are looking for   :)
>
> -Anoop-
> ________________________________________
> From: Shumin Wu [[EMAIL PROTECTED]]
> Sent: Thursday, October 11, 2012 4:54 AM
> To: [EMAIL PROTECTED]
> Subject: Re: Temporal in Hbase?
>
> How I can miss this reply!!
>
> Hi Anoop,
>
> First, thanks for your reply to my question and apologize for not
> following
> up promptly. I have put off a million of fires and come back to this
> issue.
> Here are my thoughts. Yes, a FilterList with MUST_PASS_ALL works fine
> for
> simple temporal clause.
>
> However, I have a use case like this. I need to find all data having
> overlapping time range for a given time range. Some data are valid till
> now, which have a open-ended end time timestamp, marked as end_time > null
> in our database.
>
> To express it formally, for a given time range [const_st, const_end],
> where
> const_st represents the constant start time and const_et the constant
> end
> time, my task is to find all data rows with start_time and end_time
> satisfying this expression:
>
> start_time < const_et and end_time >= const_st or end_time is null.
>
>
> In a FilterList, I can choose either MUST_PASS_ALL or MUST_PASS_ONE,
> but
> none is applicable to this use case.
>
> It would be nice if there is a temporal filter that allows me to select
> data valid between [const_st, const_et] (and that end_time is null will
> be
> automatically interpreted as valid up to now).
>
> My domain is not traditionally Internet area, but I am sure folks in
> clickstream business have a similar need. And I am wondering how they
> solve
> this problem.
>
> Temporal is commonly supported in traditional databases. So maybe HBase
> can
> offer the same? I guess the current version does not have this support,
> and
> a customer filter needs to be written by myself. I could be wrong.
> Please
> enlighten me.
>
>
> Shumin Wu
>
>
>
>
>
> On Mon, Sep 17, 2012 at 8:16 PM, Anoop Sam John <[EMAIL PROTECTED]>
> wrote:
>
> > Hi
> > start_time and end_time are 2 qualifiers in your table.
> > You can use a FilterList with MUST_PASS_ALL ( AND condition)
> > Add SingleColumnValueFilter for each of the qualifier with the value
> and
> > condition..
> >
> > -Anoop-
> >
> > ________________________________________
> > From: Shumin Wu [[EMAIL PROTECTED]]
> > Sent: Monday, September 17, 2012 9:58 PM
> > To: [EMAIL PROTECTED]
> > Subject: Temporal in Hbase?
> >
> > Hi,
> >
> > I have a user case to "filter" out rows using an "as of" predicate.
> For
> > example, given a specific time point T, I would like to find all rows
> where
> > start_time<=T<=end_time.