rc = DBexecute("delete from problem where r_clock<>0 and r_clock<%d", now - SEC_PER_DAY);

zabbix=> explain analyze select * from problem where r_clock<>0 and r_clock < 1595774180;
                                            QUERY PLAN                                             
---------------------------------------------------------------------------------------------------
 Seq Scan on problem  (cost=0.00..29.63 rows=5 width=78) (actual time=0.871..0.871 rows=0 loops=1)
   Filter: ((r_clock <> 0) AND (r_clock < 1595774180))
   Rows Removed by Filter: 1042
 Total runtime: 0.947 ms
(4 行)

zabbix=> explain analyze select * from problem where r_clock between 1 and (1595774180 - 1);
                                                     QUERY PLAN                                                     
--------------------------------------------------------------------------------------------------------------------
 Index Scan using problem_2 on problem  (cost=0.00..9.17 rows=5 width=78) (actual time=0.031..0.031 rows=0 loops=1)
   Index Cond: ((r_clock >= 1) AND (r_clock <= 1595774179))
 Total runtime: 0.058 ms
(3 行)