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Hi,
I'm reloading data from Oracle database. It returns normally ca. 500k records. So with the transformations QV loads it for about an hour.
Today I started the reload at t, and after 0,5 hrs someone truncated the database table [so in the middle of the reload process].
My question is: if the QV started to process "SQL Select" part will I get all the data [500k]?
General question: does QV first executes the SQL SELECT and then stores all data from the query [how] and then transforms it or does it do it in parts [get 1 ->transform 1 ->get 2 -> transform 2 -> concatenate .....]?
Regards
Andrzej
EDIT:
the data came through complete so i assume that first the SQL SELECT is executed as a whole, if someone could confirm it would be nice.
I think this is Oracle database consistency mechanism. When you start select Oracle freezes all changes for your request. In your case Oracle created "copy" of truncated table.
Data Concurrency and Consistency
Statement-Level Read Consistency block