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HBase, mail # user - How to get row key from row value?


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Re: How to get row key from row value?
Shahab Yunus 2013-07-31, 14:08
Yup, as far as I understand. It is application specific how sophisticated
and extensive we want this to be. Unless I am off-base here (Stack or other
experts can correct me?)

Regards,
Shahab
On Wed, Jul 31, 2013 at 10:02 AM, Pavan Sudheendra <[EMAIL PROTECTED]>wrote:

> So a secondary table here is more of a temporary table which I can just do
> a get operation and get the value?
>
> Am I right?
>
> Regards,
> Pavan
> On Jul 31, 2013 7:24 PM, "Shahab Yunus" <[EMAIL PROTECTED]> wrote:
>
> > Please correct me if I am wrong but I think there is as such no hard and
> > fast technique for it. There are no constructs or method to this
> > specifically in HBase. Your client while writing have to make sure to
> write
> > to both tables: 1) the main table 2) and the secondary index table.
> > Basically it is up to you according to the use-case and application. You
> > can delegate this to a sort of a middle (separate layer from client app
> at
> > least) which takes care of maintaing consistency between the two tables.
> > This layer will be used for both read and write to implement and handle
> > your indexing. The one obvious issue that you need to take into
> > consideration is atomicity and consistency of the two tables.
> >
> > Regards,
> > Shahab
> >
> >
> > On Wed, Jul 31, 2013 at 9:37 AM, Pavan Sudheendra <[EMAIL PROTECTED]
> > >wrote:
> >
> > > Yes perfect. Could i get few examples on how to create a secondary
> lookup
> > > table?
> > >
> > >
> > > On Wed, Jul 31, 2013 at 7:01 PM, Jean-Marc Spaggiari
> > > <[EMAIL PROTECTED]> wrote:
> > > > Hi Pavan,
> > > >
> > > > for your lookup table, you need to lookup on the value? Not on the
> > they?
> > > If
> > > > that's the case, just "revert" your table into a secondary index
> lookup
> > > > table where the value will be the key, and the key will be the value.
> > > That
> > > > way you just to a get on this secondary index lookup table instead of
> > > doing
> > > > a scan...
> > > >
> > > > Make sense?
> > > >
> > > > JM
> > > >
> > > > 2013/7/31 Pavan Sudheendra <[EMAIL PROTECTED]>
> > > >
> > > >> Before inserting a row in my main table, i need to do a lookup on my
> > > >> lookup table. I'm really not sure what logic has to be behind this.
> > > >> Should i do a full table scan of the lookup table every single time
> i
> > > >> insert in the main table?
> > > >>
> > > >> Thanks jean
> > > >>
> > > >>
> > > >>
> > > >> On Wed, Jul 31, 2013 at 6:10 PM, Jean-Marc Spaggiari
> > > >> <[EMAIL PROTECTED]> wrote:
> > > >> > the best way is to insert on your lookup table each time you
> insert
> > on
> > > >> your
> > > >> > main table. That way you don't have to scan your entire main table
> > to
> > > >> build
> > > >> > the lookup table...
> > > >> >
> > > >> > If you want to filter by CF you can look at
> > > >> >
> > > >>
> > >
> >
> http://hbase.apache.org/apidocs/org/apache/hadoop/hbase/filter/FamilyFilter.html
> > > >> > .
> > > >> >
> > > >> > Basically, you have all the filters listed there:
> > > >> >
> > > >>
> > >
> >
> http://hbase.apache.org/apidocs/org/apache/hadoop/hbase/filter/package-summary.html
> > > >> >
> > > >> > You should be able to find one which match your needs.
> > > >> >
> > > >> > JM
> > > >> >
> > > >> > 2013/7/31 Pavan Sudheendra <[EMAIL PROTECTED]>
> > > >> >
> > > >> >> Hi Jean,
> > > >> >> Is there a way to specify column family, column qualifier and
> > column
> > > >> >> value to get the row key without having to scan the table every
> > > single
> > > >> >> time?
> > > >> >> Basically, i'm building a lookup table which helps in insertion
> of
> > > >> >> another HBase table. its quite complicated to explain.
> > > >> >>
> > > >> >> On Wed, Jul 31, 2013 at 5:53 PM, Jean-Marc Spaggiari
> > > >> >> <[EMAIL PROTECTED]> wrote:
> > > >> >> > Hi Pavan,
> > > >> >> >
> > > >> >> > Are you looking for something like
> > > >> >> >
> > > >> >>
> > > >>
> > >
> >
> http://hbase.apache.org/apidocs/org/apache/hadoop/hbase/filter/ValueFilter.html