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UNDO Read and GTT- Global temporary table

Deepak MahtoNov 22 2014 — edited Nov 23 2014

Hi Expert!

Based on an analysis done by my colleagues.. He mentions about a SQL comprising of fetching Data only from a GTT and doing UNDO Reads!!!(Current_obj# from ash captured as 0 and wait event - db_file_sequential_read)

Thinking hard to get a reason for UNDO Read in case of  GTT Data fetch!!!!.

On Rollback, Undo would be required!!

But as GTT is Session specific, at any point in time within my session we would read the latest copy for any operations. That read should be from Buffer or disk (Temp).

Why a read from undo will be required?

Can you please help me understand a scenario where undo read for GTT is valid or unrealistic?

Or conceptually missing something?

This post has been answered by unknown-7404 on Nov 22 2014
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