RE: Worlds largest Data Warehouse ?
- From: "Mark Anderson" <fnmpa@xxxxxxx>
- To: p.mclarty@xxxxxxxxxx
- Date: Thu, 18 Oct 2007 20:01:38 -0800 (AKDT)
I'm not sure this is the right forum for a Sybase discussion but a couple
of clarifications:
(snip)
>
> Actually it has a lot to do with Oracle. Yes, so what Sybase could load
> a very big DW, what they don't show is when they were doing the queries,
> what was there transaction isolation level.
> Default of Sybase SQL Server is "dirty read".
No it's not. The default isolation level of Sybase Adaptive Server
Enterprise is isolation level 1, Read Committed -- a transaction is
allowed to read only committed changes to data. This has been the default
isolation level in Sybase since I started working with it in 1991, back
when it was still called Sybase SQL Server. Isolation level 0, what you
are talking about, can be configured at the session or statement level but
it is never the default.
More to the point, the DW discussed in the referenced article uses Sybase
IQ, which is a completely different product from a completely different
code base than Sybase ASE (nee SQL Server). So your experience and mine
with Sybase ASE/SQL Server is not relevant to the DW described in the
article.
best wishes,
Mark
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