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https://issues.jboss.org/browse/TEIID-1801?page=com.atlassian.jira.plugin...
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Mark Addleman edited comment on TEIID-1801 at 11/11/11 11:33 PM:
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Suppose I have a query that does a left join between a constant data source and a
streaming data source such as
SELECT constant.pkey, stream.b FROM constant LEFT JOIN stream ON
constant.pkey=stream.fkey
In time period zero, constant.pkey is "abc" but stream.fkey produces nothing so
the result set is naturally ("abc", null). In time period one, stream.fkey
produces "abc" and stream.b produces "123" but, since the constant
data source is not streaming, it produces nothing. Arguably, there are two possible
correct behaviors: Either produce ("abc", "123") or produce an empty
result set. Based on our discussions, I believe Teiid's behavior would be to produce
the empty result set in time period one since the engine doesn't have a concept of
constant.
Do I understand correctly? Is there a large cost in supporting a "constantly"
hint so I could express something like:
SELECT constant.pkey, stream.b FROM /* constantly */ constant LEFT JOIN stream on
constant.pkey=stream.fkey
The semantics would be to repeat the initial values from the constant data source every
time the join is evaluated.
was (Author: markaddleman):
Suppose I have a query that does a left join between a constant data source and a
streaming data source such as
SELECT constant.pkey, stream.b FROM constant LEFT JOIN stream ON
constant.pkey=stream.fkey
In time period zero, constant.pkey is "abc" but stream.b produces nothing so the
result set is naturally ("abc", null). In time period one, stream.a produces
"123" but, since the constant data source is not streaming, it produces nothing.
Arguably, there are two possible correct behaviors: Either produce ("abc",
"123") or produce an empty result set. Based on our discussions, I believe
Teiid's behavior would be to produce the empty result set in time period one since the
engine doesn't have a concept of constant.
Do I understand correctly? Is there a large cost in supporting a "constantly"
hint so I could express something like:
SELECT constant.pkey, stream.b FROM /* constantly */ constant LEFT JOIN stream on
constant.pkey=stream.fkey
The semantics would be to repeat the initial values from the constant data source every
time the join is evaluated.
Async Event Processing: Reset and Re-run plan
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Key: TEIID-1801
URL:
https://issues.jboss.org/browse/TEIID-1801
Project: Teiid
Issue Type: Feature Request
Reporter: Mark Addleman
Assignee: Steven Hawkins
In order to processing a stream of events aggregated within a specified time window, the
engine should provide some way of specifying the time period (analogous to a window),
reset and re-rerun the plan for every time period. There should also be an engine to
translator callback indicating that the plan has been reset as opposed to closed.
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