Comments on: Oracle Exadata hybrid columnar compression

By: Oracle Exadata 2 capacity pricing | DBMS2 -- DataBase Management System Services

Mon, 05 Oct 2009 12:20:22 +0000

[...] These figures are highly sensitive to assumptions about Oracle’s hybrid columnar compression. [...]

By: Notes on the Oracle Database 11g Release 2 white paper | DBMS2 -- DataBase Management System Services

Mon, 21 Sep 2009 17:14:34 +0000

[...] Oracle Database 11g Release 2 white paper I cited a couple of weeks ago has evidently been edited, given that a phrase I quoted last month is no longer to be found. Anyhow, [...]

By: Relational databases: are they obselete?

Relational databases: are they obselete? — Wed, 16 Sep 2009 18:04:47 +0000

[...] frequently catching up to specialized engines. In particular, they are not limited to row stores. Curt Monash’s blog post on Oracle’s hybrid columnar approach makes this obvious. Nicolas Bruno, in Teaching an Old [...]

By: Curt Monash

Curt Monash — Fri, 04 Sep 2009 17:10:17 +0000

Ankush,

Correct. But in the case of Netezza and Exadata you’re paying for the equipment (and electricity) that does the initial I/O and filtering.

Netezza’s argument is “Yeah, but that’s not so bad because FPGAs are cheap.” Even so, it’s not free.

By: Ankush

Ankush — Fri, 04 Sep 2009 17:02:02 +0000

>> in Oracle’s case I would guess “hybrid columnar
>> compression” provides the compression benefits
>> of column stores, but not column stores’ I/O
>> benefits

I was wondering if we consider a table with 10 columns; and a query Q is interested in only 2 columns – with architectures like Netezza and Exadata, if the unnecessary 8 columns are filtered and are never sent to the DB by storage servers – (network) IO perceived by the DB should be somewhat similar to what column stores see, no?

By: Curt Monash

Curt Monash — Fri, 04 Sep 2009 15:37:46 +0000

Dan,

The idea of a PAX-like scheme is that you take a certain subset of the rows (i.e., enough to fill a block, or in the case of Oracle evidently enough to fill a number of blocks) and store them VERY much as you would in a column store. Now, do you get a better compression ratio on 10s of terabytes of data than you do on megabytes or 10s of megs? Yes. But it’s my understanding that for many data sets, the difference isn’t really very much.

By: Daniel Weinreb

Daniel Weinreb — Fri, 04 Sep 2009 13:37:39 +0000

If I understand this correctly, then I would not precisely say that they get the compression benefits of column stores. I’d say that they get compression benefits, which column stores also get. But column stores may be able to do more effective compression because they are compressing a sequence of values drawn from the same domain of data. I don’t know how big this effect is, but it might be significant for all I know.

By: Changing your perspective: horizontal, vertical and hybrid data models

Changing your perspective: horizontal, vertical and hybrid data models — Fri, 04 Sep 2009 13:34:13 +0000

[...] hybrids. For example, text search sometimes require full-text indexes such as suffix arrays, Oracle recently announced a row/column hybrid, and so on. Take away message: If you are stuck, try to rotate your data model. If neither the [...]

By: Daniel Abadi

Daniel Abadi — Thu, 03 Sep 2009 23:07:08 +0000

Oracle’s is the third hybrid row/column storage scheme announced in the last month. It’s time for a taxonomy: http://dbmsmusings.blogspot.com/2009/09/tour-through-hybrid-columnrow-oriented.html

By: Curt Monash

Curt Monash — Thu, 03 Sep 2009 19:18:43 +0000

If you’re really getting close-to-columnar levels of compression, that’s indeed better than Netezza’s rates.