It seems quite strange to me that we calculate total_pages before any
partition pruning and constraint exclusion is performed during
set_base_rel_sizes(). Wouldn't it be better to wait until after that's
done so we don't mistakenly count relations we're not going to scan?
Delaying the calculation until after set_base_rel_sizes() means it's
still done in time before it's needed in set_base_rel_pathlists().
The attached patch implements the change.
There are no visible plan changes in the regression tests, but the
change can affect the plans for larger partitioned tables.
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David Rowley http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
