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chill3che 99 posts Joined 10/12
17 Dec 2013
Union and Union All - processes

Greetings Experts,
 
Can you please explain the following
The “union” command can be used to break up a large sql process or statement into several smaller sql processes or statements, which would run in parallel. But these could then cause spoolspace limit problems. “Union all” executes the sql’s single threaded
 
Why does union run using different processes unlike of union all which uses single process I guess.

Thanks, Cheeli
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