[teiid-dev] Connectors, data source, and timestamps

[Steven Hawkins]

Java's notion of a timestamp is roughly the same as a dbms TIMESTAMP WITH TIME ZONE in that they both represent an absolute time.  So for Teiid once we've read in a timestamp, regardless of its source, it's supposed to represent an absolute time (source timezone information is lost).  For display and conversion purposes the the timezone of our timestamps is then taken to be the same as the default timezone of the Java instance we're running under.  

Connectors typically then do not have to concern themselves explicitly with time zones as long as the source contract is to create a timestamp object that represents the appropriate absolute time.

----- Original Message -----
From: "Larry O'Leary" <loleary at redhat.com>
To: "teiid-dev" <teiid-dev at lists.jboss.org>
Sent: Tuesday, January 12, 2010 12:59:43 PM GMT -06:00 US/Canada Central
Subject: [teiid-dev] Connectors, data source, and timestamps

I have been looking into some legacy issues regarding date/time values
and time zone offsets.  I am well aware that the DBMS recommendation is
to store time values in a consistent, predetermined time zone.  I think
in principle this recommendation works but what about a federated query
engine that has clients connecting from many different geographies?  

Also, how about the Oracle TIMESTAMP WITH TIME ZONE data type?  It seems
that this even complicates matters more?

Are the connectors handling such logic?  Do they need to?  Does Teiid
plan to offer a recommendation regarding setting and retrieving of time
values and appropriate time zone or locale information?
-- 
Larry O'Leary <loleary at redhat.com>
Red Hat, Inc.

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