> Date: Wed, 14 Apr 2010 12:03:56 +0600
> Subject: Re: Porting SQL DB into HBASE
> From: [email protected]
> To: [email protected]
>
> On Mon, Apr 12, 2010 at 2:55 PM, kranthi reddy <[email protected]>
> wrote:
> >
> > <snip />
> > The problem is denormalising these 20% tables is also extremely difficult
> > and we are planning to port them directly into hbase. And also denormalising
> > these tables would lead to a lot of redundant data.
> >
>
> When denormalisation is been mentioned, it is implied having redundant
> data. The idea is as there is no join instead of doing N lookups (to
> replace N joins) keeping redundant data will allow you to do a single
> lookup and furthermore, HBase is great in scaling huge data sets.
>
>From reading his last post, I suspect its less of an issue of denormalization
>than one of poor database design.
Paraphrasing his example, he has one table for users who access his system by
phone. He has one table for users who access the system by van.
Without looking at his table structures, its hard to see why he can't combine
the two and then have a single field to denote access type (phone, van, etc
...) Even if there are fields that are unique to phone and fields that are
unique to van, it doesn't mean that they can't be null.
Again, sometimes you have to look at alternatives to how you achieve your
physical model of your database.
If you have a parent/child relationship between data, you can easily use a
hierarchical model like Pick (U2,Revelation, etc) Not that I'm really a fan of
Dick Pick (RIP) but this model would fit within HBase and work well. (I should
add a caveat on column width and table size, but that's a different issue)
Going back to the problem the OP is having, he really needs to rethink his
design.
IMHO, I think one important issue that doesn't get addressed is thinking of
your database as something more than a way to persist your objects. ;-) [And
that is one thing that you debate at a bar, over beers (or your favorite
beverage) :-) ]
HTH
-Mike
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