psql \d(+) doesn't show any information about UNLOGGED and TEMP attributes
for the table. So, we cannot know the table is unlogged or not unless
we directly select from pg_class.relpersistence. Is this a TODO item?
The same issue is in TEMP tables, but we can determine them by their
schema; they are always created in pg_temp_N schema.
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Itagaki Takahiro