Re: Check each of base restriction clauses for constant-FALSE-or-NULL

postgres@312571=# explain (analyze, costs off) select * from pg_class
t1 where oid = 1 and oid = 2;
                                QUERY PLAN
---------------------------------------------------------------------------
 Result (actual time=0.002..0.003 rows=0 loops=1)
   One-Time Filter: false
   ->  Index Scan using pg_class_oid_index on pg_class t1 (never executed)
         Index Cond: (oid = '1'::oid)
 Planning Time: 0.176 ms
 Execution Time: 0.052 ms
(6 rows)

You will see that the scan node was never executed. Hence there's no
execution time benefit if we remove the scan plan.

Where do we produce the single baserestrictinfo mentioned in the
comments? Is it before the planning proper starts?

get_gating_quals does what you are doing much earlier in the query
processing. Your code would just duplicate that.