"Michael P. McDonnell" <bzaks1...@gmail.com> writes:
> On Sun, May 7, 2023 at 4:25 PM Tom Lane <t...@sss.pgh.pa.us> wrote:
>> Perhaps an "ANALYZE table_b" in between would help.
> Okay - that worked.
> How did you know that would work? That's incredible.
Well, I guessed ;-) ... but it was a well-educated guess.
The symptoms sounded like you were getting a bad plan choice for
the second query, which is unsurprising if you populate a table
from empty and don't give auto-analyze enough time to collect
some statistics behind your back.
As a solution going forward, I'd recommend adding the ANALYZE
as the last step in the table-populating procedure.
regards, tom lane
