Postgresの計画は実行に無駄な時間がかかります

Question

アマゾンRDSで実行中のpostgres 9.6。キャンペーンの定義と小さなテーブル - - 6つのキー（IDS）

キャンペーンのメタデータを持つ大きなテーブル

1. 集約イベント：
   は、私は2つのテーブルを持っています。

キャンペーン名のようなメタデータをフィルタリングするために2に参加します。

クエリは、キャンペーンのチャンネルと日付別に表示される内訳のレポートを取得するためのものです（日付は毎日です）。

いいえFKといい、nullではありません。レポートテーブルにはキャンペーンごとに1日に複数の行があります（アグリゲーションは6つの属性キーに基づいているため）。

私が参加し、クエリプランは、（300ミリ秒対）10Sに成長

explain analyze select c.campaign_channel as channel,date as day , sum(displayed) as displayed 
from report_campaigns c 
left join events_daily r on r.campaign_id = c.c_id 
where provider_id = 7726 and c.p_id = 7726 and c.campaign_name <> 'test' 
and date >= '20170513 12:00' and date <= '20170515 12:00' 
group by c.campaign_channel,date; 
                         QUERY PLAN 
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- 
GroupAggregate (cost=71461.93..71466.51 rows=229 width=22) (actual time=104.189..114.788 rows=6 loops=1) 
    Group Key: c.campaign_channel, r.date 
    -> Sort (cost=71461.93..71462.51 rows=229 width=18) (actual time=100.263..106.402 rows=31205 loops=1) 
     Sort Key: c.campaign_channel, r.date 
     Sort Method: quicksort Memory: 3206kB 
     -> Hash Join (cost=1092.52..71452.96 rows=229 width=18) (actual time=22.149..86.955 rows=31205 loops=1) 
       Hash Cond: (r.campaign_id = c.c_id) 
       -> Append (cost=0.00..70245.84 rows=29948 width=20) (actual time=21.318..71.315 rows=31205 loops=1) 
        -> Seq Scan on events_daily r (cost=0.00..0.00 rows=1 width=20) (actual time=0.005..0.005 rows=0 loops=1) 
          Filter: ((date >= '2017-05-13 12:00:00'::timestamp without time zone) AND (date <= '2017-05-15 12:00:00'::timestamp without time zone) AND (provider_id = 
        -> Bitmap Heap Scan on events_daily_20170513 r_1 (cost=685.36..23913.63 rows=1 width=20) (actual time=17.230..17.230 rows=0 loops=1) 
          Recheck Cond: (provider_id = 7726) 
          Filter: ((date >= '2017-05-13 12:00:00'::timestamp without time zone) AND (date <= '2017-05-15 12:00:00'::timestamp without time zone)) 
          Rows Removed by Filter: 13769 
          Heap Blocks: exact=10276 
          -> Bitmap Index Scan on events_daily_20170513_full_idx (cost=0.00..685.36 rows=14525 width=0) (actual time=2.356..2.356 rows=13769 loops=1) 
           Index Cond: (provider_id = 7726) 
        -> Bitmap Heap Scan on events_daily_20170514 r_2 (cost=689.08..22203.52 rows=14537 width=20) (actual time=4.082..21.389 rows=15281 loops=1) 
          Recheck Cond: (provider_id = 7726) 
          Filter: ((date >= '2017-05-13 12:00:00'::timestamp without time zone) AND (date <= '2017-05-15 12:00:00'::timestamp without time zone)) 
          Heap Blocks: exact=10490 
          -> Bitmap Index Scan on events_daily_20170514_full_idx (cost=0.00..685.45 rows=14537 width=0) (actual time=2.428..2.428 rows=15281 loops=1) 
           Index Cond: (provider_id = 7726) 
        -> Bitmap Heap Scan on events_daily_20170515 r_3 (cost=731.84..24128.69 rows=15409 width=20) (actual time=4.297..22.662 rows=15924 loops=1) 
          Recheck Cond: (provider_id = 7726) 
          Filter: ((date >= '2017-05-13 12:00:00'::timestamp without time zone) AND (date <= '2017-05-15 12:00:00'::timestamp without time zone)) 
          Heap Blocks: exact=11318 
          -> Bitmap Index Scan on events_daily_20170515_full_idx (cost=0.00..727.99 rows=15409 width=0) (actual time=2.506..2.506 rows=15924 loops=1) 
           Index Cond: (provider_id = 7726) 
       -> Hash (cost=1085.35..1085.35 rows=574 width=14) (actual time=0.815..0.815 rows=582 loops=1) 
        Buckets: 1024 Batches: 1 Memory Usage: 37kB 
        -> Bitmap Heap Scan on report_campaigns c (cost=12.76..1085.35 rows=574 width=14) (actual time=0.090..0.627 rows=582 loops=1) 
          Recheck Cond: (p_id = 7726) 
          Filter: ((campaign_name)::text <> 'test'::text) 
          Heap Blocks: exact=240 
          -> Bitmap Index Scan on report_campaigns_provider_id (cost=0.00..12.62 rows=577 width=0) (actual time=0.062..0.062 rows=582 loops=1) 
           Index Cond: (p_id = 7726) 
Planning time: 9651.605 ms 
Execution time: 115.092 ms 


result: 
channel |   day   | displayed 
----------+---------------------+----------- 
Pin  | 2017-05-14 00:00:00 | 43434 
Pin  | 2017-05-15 00:00:00 | 3325325235 

Answer 1

私は、これは左参加する前に事前計算を強制するために合計である私には思えます。

解決策は、左結合および合計の前に2つのネストされたサブSELECTにWHERE句をフィルタリングすることでした。

・ホープ、この作品：

SELECT channel, day, sum(displayed) 
FROM 
(SELECT campaign_channel AS channel, date AS day, displayed, p_id AS c_id 
FROM report_campaigns WHERE p_id = 7726 AND campaign_name <> 'test' AND date >= '20170513 12:00' AND date <= '20170515 12:00') AS c, 
(SELECT * FROM events_daily WHERE campaign_id = 7726) AS r 
LEFT JOIN r.campaign_id = c.c_id 
GROUP BY channel, day;