> 2. A combination of constraints on the partitions should be applicable to > the parent. We aren't doing that.
How about on seeing that a RELOPT_OTHER_MEMBER_REL is partitioned parent table, we can have get_relation_constraints() include a constant false clause in the list of constraints returned for relation_excluded_by_constraints() to process so that it is not included in the append result by way of constraint exclusion. One more option is to mark such rels dummy in set_rel_size().
I am not complaining about having parent relation there. For the people who are used to seeing the parent relation in the list of append relations, it may be awkward. But +1 if we can do that. If we can't do that, we should at least mark with an OR of all constraints on the partitions, so that constraint exclusion can exclude it if there are conditions incompatible with constraints. This is what would happen in inheritance case as well, if there are constraints on the parent. In the above example, the parent table would have constraints CHECK ((a >= 0 AND a < 250) OR (a >= 250 and a < 500) OR (a >= 500 or a < 600)). It will probably get excluded, if constraint exclusion is smart enough to understand ORing.
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Best Wishes, Ashutosh Bapat EnterpriseDB Corporation The Postgres Database Company
