Asynchronous querying and tabular data
patrick.dowler at nrc-cnrc.gc.ca
Wed May 2 00:15:53 PDT 2007
On Tuesday 01 May 2007 21:02, Doug Tody wrote:
> The result, if a large query is attempted synchronously, is truncation
> or an error response; alternatively, we for serious large queries we
> have a two-stage operation involving estimation and job submission.
> This is basically what queryData/stageData concept already provides.
I am afraid you have lost me here. I see no reason to infer that queryData is
some sort of estimate on the work required to do the real thing. In SIA it is
a query and returns the query result. It happens that the query result itself
describes something else and one column (hopefully) contains a URL to the
something else. It is not an estimate.
TAP queries may contain a column with a URL to something, but the standard
case is that the query result is something in its own right and not generally
the first of two stages of work. In this light, I think it is a perfectly
reasonable interpretation of typical DAL style to say that queryData is a
synchronous method that returns a query result.
Sorry to be blunt, but I just don't see the connection between what I see in
DAL and what you are saying.
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