sql 字段先计算后再拿比对的字段进行比对 效率提升100倍

关于日期索引的使用，不要计算后再对比，否则使用不了索引
例如：以下执行不了索引，耗时很大

 dywl=# explain analyze SELECT
                           car_bill.billno,car_bill.beginunit,car_bill.begincity,car_bill.endunit,car_bill.endcity,car_bill.pubtime,car_bill.goodstype,car_bill.mobile,
                           ST_Distance_Sphere(car_bill.point_geom,ST_GeometryFromText('POINT(113.91269 35.307258)',4326)) as leng,
                           sys_user.name,car_bill.totaltone,car_bill.weight,car_bill.carriage,car_bill.carriageunit,car_bill.remark
                       FROM
                           car_bill,sys_user
                       WHERE
                           EXTRACT(EPOCH FROM now()- car_bill.pubtime) < 60
                       and
                           car_bill.userid=sys_user.userid
                       and
                           ST_Distance_Sphere(car_bill.point_geom,ST_GeometryFromText('POINT(113.91269 35.307258)',4326))<=200000
                       ORDER BY
                           car_bill.point_geom <-> ST_GeometryFromText('POINT(113.91269 35.307258)',4326)    ;

  QUERY PLAN                                          

 ------------------------------------------------------------------
  Sort  (cost=258916.19..259035.52 rows=47734 width=146) (actual time=565.754..565.754 rows=0 loops=1)
    Sort Key: ((car_bill.point_geom <-> '0101000020E6100000B8585183697A5C4099B7EA3A54A74140'::geometry))
    Sort Method: quicksort  Memory: 25kB
    ->  Hash Join  (cost=59228.31..251615.60 rows=47734 width=146) (actual time=565.745..565.745 rows=0 loops=1)
          Hash Cond: ((car_bill.userid)::text = (sys_user.userid)::text)
          ->  Seq Scan on car_bill  (cost=0.00..173902.11 rows=47734 width=153) (actual time=565.743..565.743 rows=0 loops=1)
                Filter: ((date_part('epoch'::text, (now() - (pubtime)::timestamp with time zone)) < 60::double precision) AND (_st_distance(geography(point_geom), '0101000020E6100000B8585183
 697A5C4099B7EA3A54A74140'::geography, 0::double precision, false) <= 200000::double precision))
                Rows Removed by Filter: 423616
          ->  Hash  (cost=49538.47..49538.47 rows=527747 width=17) (never executed)
                ->  Seq Scan on sys_user  (cost=0.00..49538.47 rows=527747 width=17) (never executed)
  Planning time: 1.064 ms
  Execution time: 565.836 ms
 (12 rows)

变更为以下后，可走索引，提升百倍，所以下面的才是正确的

 dywl=#  explain analyze SELECT
 dywl-#                           car_bill.billno,car_bill.beginunit,car_bill.begincity,car_bill.endunit,car_bill.endcity,car_bill.pubtime,car_bill.goodstype,car_bill.mobile,
 dywl-#                           ST_Distance_Sphere(car_bill.point_geom,ST_GeometryFromText('POINT(113.91269 35.307258)',4326)) as leng,
 dywl-#                           sys_user.name,car_bill.totaltone,car_bill.weight,car_bill.carriage,car_bill.carriageunit,car_bill.remark
 dywl-#                       FROM
 dywl-#                           car_bill,sys_user
 dywl-#                       WHERE
 dywl-#                           car_bill.pubtime > now() - interval '60 seconds'
 dywl-#                           and car_bill.userid=sys_user.userid
 dywl-#                           and ST_Distance_Sphere(car_bill.point_geom,ST_GeometryFromText('POINT(113.91269 35.307258)',4326))<=200000
 dywl-#                       ORDER BY
 dywl-#                           car_bill.point_geom <-> ST_GeometryFromText('POINT(113.91269 35.307258)',4326)
 dywl-# ;

 QUERY PLAN
 ----------------------------------------------------------------------------------------------------------
  Sort  (cost=4424.85..4425.43 rows=235 width=146) (actual time=0.369..0.369 rows=0 loops=1)
    Sort Key: ((car_bill.point_geom <-> '0101000020E6100000B8585183697A5C4099B7EA3A54A74140'::geometry))
    Sort Method: quicksort  Memory: 25kB
    ->  Nested Loop  (cost=0.85..4415.59 rows=235 width=146) (actual time=0.351..0.351 rows=0 loops=1)
          ->  Index Scan using car_bill_pubtime_idx on car_bill  (cost=0.43..2388.74 rows=235 width=153) (actual time=0.351..0.351 rows=0 loops=1)
                Index Cond: ((pubtime)::timestamp without time zone > (now() - '00:01:00'::interval))
                Filter: (_st_distance(geography(point_geom), '0101000020E6100000B8585183697A5C4099B7EA3A54A74140'::geography, 0::double precision, false) <= 200000::double precision)
                Rows Removed by Filter: 1
          ->  Index Scan using sys_user_userid on sys_user  (cost=0.42..8.36 rows=1 width=17) (never executed)
                Index Cond: ((userid)::text = (car_bill.userid)::text)
  Planning time: 1.161 ms
  Execution time: 0.483 ms
 (12 rows)