Re: Oracle Exadata Machine
- From: Sergey Popov <sspopov@xxxxxxxxx>
- To: "oracle-l@xxxxxxxxxxxxx" <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 14 May 2009 21:15:30 -0400
I'm not understanding why everybody got stuck on Exadata I/O
throughput. Just having a fast filesystem is not enough to guarantee
lowest query execution time. How is it different from measuring
performance using cache hit ration?
What's important is to have intelligent storage that does table joins,
sorting and aggregation to minimize the final result set to be
transferred to the DB host. What can Exadata offer from this
prospective:
1) Row elimination based on a predicates received
2) Start transformation
I know for sure it does not have the following functionality:
1) Hash join
2) Merge join
Not sure about sorting and aggregation.
What Netezza offers on this department:
1) Predicate based row elimination
2) Hash join
3) Merge join
4) Sorting
5) Aggregation
All of that is happening at the storage level. The fact is as long as
the data is distributed correctly there is no need to transfer huge
result sets from storage to host to execute joins. Even with less than
perfect row distribution Netezza does SPU-to-SPU re-distribution
bypassing host all together. End of day join is a row elimination as
well.
Netezza has partitions as all data is distributed either based on a
hash (column) or randomly. There are materialized views but they can
be created on a single table only and in fact look more like indexes
or limited materialized result sets distributed on a different key.
Netezza documentation is very limited compare to Oracle. Lots of
command line utilities and shell scripts involved in administration.
NZPLSQL is introduced in version 4.6 but performance is something.
Inserting < 900 rows into a single column table in a loop takes
minutes.
Most of us don't have worm and fuzzy feeling about Oracle release 1
products. Uncertainty in relationship with HP after SUN acquisition
contributing to the slow adoption problem as well.
I never worked for either company. I work with Oracle products since
'92 and just happened to have an opportunity to work with Netezza on
my current project.
Sergey
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