Mailing-List: contact user-help@cassandra.apache.org; run by ezmlm
Precedence: bulk
Reply-To: user@cassandra.apache.org
Received-SPF: pass (athena.apache.org: local policy)
DomainKey-Signature: a=rsa-sha1; c=nofws; d=thelastpickle.com; h=from
	:mime-version:content-type:subject:date:in-reply-to:to
	:references:message-id; q=dns; s=thelastpickle.com; b=Ut7NzIW7bo
	sHZ1OYu/6/8WzyvvW68J2sq6KwfAzac4QiKiWi/rdLdD2ASOhgbJvpQA4g/u8tGZ
	KGeIHcFGxLFBP/0PR4yTMgNsFx+4ROIIwPiu/O7xg80toPi+Uwwt8qY/7WpNbo3e
	lNzuEVWdlDRsjBHgyLqQhJMK4PrXei86E=
From: aaron morton <aaron@thelastpickle.com>
Mime-Version: 1.0 (Apple Message framework v1084)
Content-Type: multipart/alternative; boundary=Apple-Mail-26-195089474
Subject: Re: Indexes on heterogeneous rows
Date: Thu, 14 Apr 2011 21:12:00 +1200
In-Reply-To: <BANLkTikOX+0OCWsdi5Aa-wjoaNLm5E3u8A@mail.gmail.com>
To: user@cassandra.apache.org
References: <BANLkTikOX+0OCWsdi5Aa-wjoaNLm5E3u8A@mail.gmail.com>
Message-Id: <8B700116-AFCF-490E-9C6F-19F0A2F76D21@thelastpickle.com>


--Apple-Mail-26-195089474
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain;
	charset=us-ascii

Need to clear up some terminology here.=20

Rows have a key and can be retrieved by key. This is *sort of* the =
primary index, but not primary in the normal RDBMS sense.=20
Rows can have different columns and the column names are sorted and can =
be efficiently selected.
There are "secondary indexes" in cassandra 0.7 based on column values =
http://www.datastax.com/dev/blog/whats-new-cassandra-07-secondary-indexes

So you could create secondary indexes on the a,e, and h columns and get =
rows that have specific values. There are some limitations to secondary =
indexes, read the linked article.=20

Or you can make your own secondary indexes using row keys as the index =
values.

If you have billions of rows, how many do you need to read back at once?

Hope that helps
Aaron
   =20
On 14 Apr 2011, at 04:23, David Boxenhorn wrote:

> Is it possible in 0.7.x to have indexes on heterogeneous rows, which =
have different sets of columns?
>=20
> For example, let's say you have three types of objects (1, 2, 3) which =
each had three members. If your rows had the following pattern
>=20
> type=3D1 a=3D? b=3D? c=3D?
> type=3D2 d=3D? e=3D? f=3D?
> type=3D3 g=3D? h=3D? i=3D?
>=20
> could you index "type" as your primary index, and also index "a", "e", =
"h" as secondary indexes, to get the objects of that type that you are =
looking for?
>=20
> Would it work if you had billions of rows of each type?


--Apple-Mail-26-195089474
Content-Transfer-Encoding: quoted-printable
Content-Type: text/html;
	charset=us-ascii

<html><head></head><body style=3D"word-wrap: break-word; =
-webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Need =
to clear up some terminology here.&nbsp;<div><br></div><div>Rows have a =
key and can be retrieved by key. This is *sort of* the primary index, =
but not primary in the normal RDBMS sense.&nbsp;</div><div>Rows can have =
different columns and the column names are sorted and can be efficiently =
selected.</div><div>There are "secondary indexes" in cassandra 0.7 based =
on column values&nbsp;<a =
href=3D"http://www.datastax.com/dev/blog/whats-new-cassandra-07-secondary-=
indexes">http://www.datastax.com/dev/blog/whats-new-cassandra-07-secondary=
-indexes</a></div><div><br></div><div>So you could create secondary =
indexes on the a,e, and h columns and get rows that have specific =
values. There are some limitations to secondary indexes, read the linked =
article.&nbsp;</div><div><br></div><div>Or you can make your own =
secondary indexes using row keys as the index =
values.</div><div><br></div><div>If you have billions of rows, how many =
do you need to read back at once?</div><div><br></div><div>Hope that =
helps</div><div>Aaron</div><div>&nbsp;&nbsp; =
&nbsp;</div><div><div><div>On 14 Apr 2011, at 04:23, David Boxenhorn =
wrote:</div><br class=3D"Apple-interchange-newline"><blockquote =
type=3D"cite"><div dir=3D"ltr">Is it possible in 0.7.x to have indexes =
on heterogeneous rows, which have different sets of columns?<br><br>For =
example, let's say you have three types of objects (1, 2, 3) which each =
had three members. If your rows had the following pattern<br>
<br>type=3D1 a=3D? b=3D? c=3D?<br>type=3D2 d=3D? e=3D? f=3D?<br>type=3D3 =
g=3D? h=3D? i=3D?<br><br>could you index "type" as your primary index, =
and also index "a", "e", "h" as secondary indexes, to get the objects of =
that type that you are looking for?<br>
<br>Would it work if you had billions of rows of each type?<br></div>
</blockquote></div><br></div></body></html>=

--Apple-Mail-26-195089474--