We recently performed an upgrade from pg14 (14.18) to pg16 (16.9) and performed 
the analyze-in-stages post upgrade.  It has been noticed that some plans 
changed to use hash joins instead of nested loops.  Further investigation found 
it was because the parent table of partitioned tables did not have stats.  
After running an ANALYZE on the parent tables we got similar plan an execution 
times as before.

I have two questions
1 - Why does analyze-in-stages not analyze the parent tables?
2 - What happens if we do not run analyze-in-stages post upgrade and just run 
an analyze?

Thanks,
Sean

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