具有较小日期范围(结果集)的PostgreSQL查询慢于具有较大日期范围

发布时间：2020-12-13 18:09:56 所属栏目：百科来源：网络整理

导读：当我做日期时,我在 postgresql中有一个查询在’2012-01-01’和’2012-01-04’之间它的速度较慢,即使它的记录设置较小,如果我这样做的话 ‘2012-01-01’与’2012-04-17’之间可以告诉我为什么会这样吗？这是较慢的查询： "HashAggregate (cost=9388.82..9

当我做日期时,我在 postgresql中有一个查询
在’2012-01-01’和’2012-01-04’之间
它的速度较慢,即使它的记录设置较小,如果我这样做的话
‘2012-01-01’与’2012-04-17’之间

可以告诉我为什么会这样吗？

这是较慢的查询：

"HashAggregate  (cost=9388.82..9388.88 rows=1 width=311) (actual time=187787.183..187788.001 rows=153 loops=1)"
"  ->  Nested Loop  (cost=9266.68..9388.77 rows=1 width=311) (actual time=8432.315..187785.091 rows=153 loops=1)"
"        Join Filter: ((oh.ord_id = ord_line.ord_id) AND (iis.item_id = ord_line.item_id))"
"        ->  Nested Loop Left Join  (cost=9266.68..9373.81 rows=1 width=333) (actual time=92.238..147161.052 rows=5847933 loops=1)"
"              Join Filter: ((oh.division)::text = (item_color_cd.division)::text)"
"              ->  Nested Loop Left Join  (cost=9266.68..9373.53 rows=1 width=322) (actual time=92.214..113058.202 rows=5847933 loops=1)"
"                    Join Filter: ((oh.division)::text = (item_size_cd.division)::text)"
"                    ->  Nested Loop Left Join  (cost=9266.68..9373.24 rows=1 width=312) (actual time=92.189..77932.977 rows=5847933 loops=1)"
"                          Join Filter: ((oh.division)::text = (item_class_cd.division)::text)"
"                          ->  Nested Loop  (cost=9266.68..9372.92 rows=1 width=294) (actual time=92.183..61183.081 rows=5847933 loops=1)"
"                                ->  Nested Loop  (cost=67.45..91.07 rows=1 width=75) (actual time=0.819..58.193 rows=8463 loops=1)"
"                                      ->  Nested Loop  (cost=67.45..75.24 rows=1 width=51) (actual time=0.784..3.894 rows=360 loops=1)"
"                                            ->  Index Scan using item_dept_cd_division_key on item_dept_cd  (cost=0.00..5.27 rows=1 width=27) (actual time=0.045..0.047 rows=1 loops=1)"
"                                                  Index Cond: (((division)::text = 'BSM'::text) AND ((dept_cd)::text = 'S'::text))"
"                                                  Filter: ((dept_cd)::text ~~ 'S'::text)"
"                                            ->  Bitmap Heap Scan on item_item_num iin  (cost=67.45..69.96 rows=1 width=32) (actual time=0.734..3.315 rows=360 loops=1)"
"                                                  Recheck Cond: ((iin.dept_cd_id = item_dept_cd.dept_cd_id) AND ((iin.division)::text = 'BSM'::text))"
"                                                  ->  BitmapAnd  (cost=67.45..67.45 rows=1 width=0) (actual time=0.687..0.687 rows=0 loops=1)"
"                                                        ->  Bitmap Index Scan on item_item_num_dept_id  (cost=0.00..6.92 rows=213 width=0) (actual time=0.109..0.109 rows=364 loops=1)"
"                                                              Index Cond: (iin.dept_cd_id = item_dept_cd.dept_cd_id)"
"                                                        ->  Bitmap Index Scan on item_item_num_division_key  (cost=0.00..59.64 rows=2573 width=0) (actual time=0.544..0.544 rows=2753 loops=1)"
"                                                              Index Cond: ((iin.division)::text = 'BSM'::text)"
"                                      ->  Index Scan using item_sku_item_num_id_key on item_sku iis  (cost=0.00..15.82 rows=1 width=32) (actual time=0.021..0.104 rows=24 loops=360)"
"                                            Index Cond: (iis.item_num_id = iin.item_num_id)"
"                                            Filter: ((iis.division)::text = 'BSM'::text)"
"                                ->  HashAggregate  (cost=9199.23..9281.69 rows=8 width=66) (actual time=0.020..6.298 rows=691 loops=8463)"
"                                      ->  Nested Loop  (cost=0.01..9198.91 rows=8 width=66) (actual time=1.111..89.484 rows=691 loops=1)"
"                                            ->  Index Scan using ledger_demand_ix4 on ledger_demand ls  (cost=0.01..4512.71 rows=710 width=35) (actual time=1.078..79.178 rows=691 loops=1)"
"                                                  Index Cond: ((date(trans_date) >= '2012-01-01'::date) AND (date(trans_date) <= '2012-01-04'::date))"
"                                                  Filter: (((division)::text = 'BSM'::text) AND (((qty_ordered > 0) AND ((ledger_code)::text ~~ 'D%'::text)) OR ((ledger_code)::text ~~ 'DC%'::text)))"
"                                            ->  Index Scan using ord_header_pkey on ord_header oh  (cost=0.00..6.59 rows=1 width=39) (actual time=0.010..0.011 rows=1 loops=691)"
"                                                  Index Cond: (oh.ord_id = ls.ord_id)"
"                                                  Filter: ((oh.division)::text = 'BSM'::text)"
"                                      SubPlan 1"
"                                        ->  Aggregate  (cost=10.25..10.26 rows=1 width=8) (actual time=0.005..0.006 rows=1 loops=5847933)"
"                                              ->  Index Scan using ledger_discount_ord_line_id on ledger_discount  (cost=0.00..10.25 rows=1 width=8) (actual time=0.003..0.004 rows=0 loops=5847933)"
"                                                    Index Cond: (ord_line_id = $2)"
"                                                    Filter: (((ledger_code)::text ~~ 'D%'::text) AND ((division)::text = ($0)::text) AND (ord_id = $1) AND (date(trans_date) = date($3)))"
"                          ->  Index Scan using item_class_cd_pkey on item_class_cd  (cost=0.00..0.30 rows=1 width=31) (actual time=0.001..0.001 rows=0 loops=5847933)"
"                                Index Cond: (iin.class_cd_id = item_class_cd.class_cd_id)"
"                                Filter: ((item_class_cd.division)::text = 'BSM'::text)"
"                    ->  Index Scan using item_size_cd_pkey on item_size_cd  (cost=0.00..0.27 rows=1 width=25) (actual time=0.002..0.003 rows=1 loops=5847933)"
"                          Index Cond: (iis.size_cd_id = item_size_cd.size_cd_id)"
"                          Filter: ((item_size_cd.division)::text = 'BSM'::text)"
"              ->  Index Scan using item_color_cd_pkey on item_color_cd  (cost=0.00..0.27 rows=1 width=25) (actual time=0.002..0.003 rows=1 loops=5847933)"
"                    Index Cond: (iis.color_cd_id = item_color_cd.color_cd_id)"
"                    Filter: ((item_color_cd.division)::text = 'BSM'::text)"
"        ->  Index Scan using ord_line_pkey on ord_line  (cost=0.00..14.94 rows=1 width=16) (actual time=0.004..0.005 rows=1 loops=5847933)"
"              Index Cond: (ord_line.ord_line_id = ls.ord_line_id)"
"              Filter: ((ord_line.division)::text = 'BSM'::text)"
"Total runtime: 187788.419 ms"

并且为了更快的查询：

"HashAggregate  (cost=395482.02..395482.08 rows=1 width=311) (actual time=3176.868..3204.741 rows=4900 loops=1)"
"  ->  Nested Loop Left Join  (cost=391021.12..395481.97 rows=1 width=311) (actual time=2074.121..3151.576 rows=5118 loops=1)"
"        Join Filter: ((oh.division)::text = (item_color_cd.division)::text)"
"        ->  Nested Loop Left Join  (cost=391021.12..395481.69 rows=1 width=314) (actual time=2074.086..3113.537 rows=5118 loops=1)"
"              Join Filter: ((oh.division)::text = (item_size_cd.division)::text)"
"              ->  Nested Loop Left Join  (cost=391021.12..395481.40 rows=1 width=304) (actual time=2074.067..3077.820 rows=5118 loops=1)"
"                    Join Filter: ((oh.division)::text = (item_class_cd.division)::text)"
"                    ->  Hash Join  (cost=391021.12..395481.11 rows=1 width=286) (actual time=2074.062..3061.180 rows=5118 loops=1)"
"                          Hash Cond: ((oh.ord_id = ord_line.ord_id) AND (ls.ord_line_id = ord_line.ord_line_id))"
"                          ->  HashAggregate  (cost=390858.20..395310.62 rows=432 width=66) (actual time=1089.300..1596.212 rows=38947 loops=1)"
"                                ->  Nested Loop  (cost=92108.27..390840.92 rows=432 width=66) (actual time=603.101..1004.552 rows=38947 loops=1)"
"                                      ->  Bitmap Heap Scan on ledger_demand ls  (cost=92108.27..174982.73 rows=36833 width=35) (actual time=603.076..708.321 rows=38947 loops=1)"
"                                            Recheck Cond: (((division)::text = 'BSM'::text) AND (date(trans_date) >= '2012-01-01'::date) AND (date(trans_date) <= '2012-04-17'::date))"
"                                            Filter: (((qty_ordered > 0) AND ((ledger_code)::text ~~ 'D%'::text)) OR ((ledger_code)::text ~~ 'DC%'::text))"
"                                            ->  BitmapAnd  (cost=92108.27..92108.27 rows=37705 width=0) (actual time=600.722..600.722 rows=0 loops=1)"
"                                                  ->  Bitmap Index Scan on ledger_demand_ix2  (cost=0.00..12712.18 rows=559935 width=0) (actual time=91.763..91.763 rows=572985 loops=1)"
"                                                        Index Cond: ((division)::text = 'BSM'::text)"
"                                                  ->  Bitmap Index Scan on ledger_demand_ix4  (cost=0.00..79377.42 rows=4397941 width=0) (actual time=483.385..483.385 rows=4444914 loops=1)"
"                                                        Index Cond: ((date(trans_date) >= '2012-01-01'::date) AND (date(trans_date) <= '2012-04-17'::date))"
"                                      ->  Index Scan using ord_header_pkey on ord_header oh  (cost=0.00..5.85 rows=1 width=39) (actual time=0.004..0.005 rows=1 loops=38947)"
"                                            Index Cond: (oh.ord_id = ls.ord_id)"
"                                            Filter: ((oh.division)::text = 'BSM'::text)"
"                                SubPlan 1"
"                                  ->  Aggregate  (cost=10.25..10.26 rows=1 width=8) (actual time=0.009..0.009 rows=1 loops=38947)"
"                                        ->  Index Scan using ledger_discount_ord_line_id on ledger_discount  (cost=0.00..10.25 rows=1 width=8) (actual time=0.007..0.007 rows=0 loops=38947)"
"                                              Index Cond: (ord_line_id = $2)"
"                                              Filter: (((ledger_code)::text ~~ 'D%'::text) AND ((division)::text = ($0)::text) AND (ord_id = $1) AND (date(trans_date) = date($3)))"
"                          ->  Hash  (cost=162.91..162.91 rows=1 width=83) (actual time=984.452..984.452 rows=112897 loops=1)"
"                                ->  Nested Loop  (cost=67.45..162.91 rows=1 width=83) (actual time=0.736..852.432 rows=112897 loops=1)"
"                                      ->  Nested Loop  (cost=67.45..91.07 rows=1 width=75) (actual time=0.705..45.978 rows=8463 loops=1)"
"                                            ->  Nested Loop  (cost=67.45..75.24 rows=1 width=51) (actual time=0.675..4.358 rows=360 loops=1)"
"                                                  ->  Index Scan using item_dept_cd_division_key on item_dept_cd  (cost=0.00..5.27 rows=1 width=27) (actual time=0.030..0.032 rows=1 loops=1)"
"                                                        Index Cond: (((division)::text = 'BSM'::text) AND ((dept_cd)::text = 'S'::text))"
"                                                        Filter: ((dept_cd)::text ~~ 'S'::text)"
"                                                  ->  Bitmap Heap Scan on item_item_num iin  (cost=67.45..69.96 rows=1 width=32) (actual time=0.641..3.818 rows=360 loops=1)"
"                                                        Recheck Cond: ((iin.dept_cd_id = item_dept_cd.dept_cd_id) AND ((iin.division)::text = 'BSM'::text))"
"                                                        ->  BitmapAnd  (cost=67.45..67.45 rows=1 width=0) (actual time=0.598..0.598 rows=0 loops=1)"
"                                                              ->  Bitmap Index Scan on item_item_num_dept_id  (cost=0.00..6.92 rows=213 width=0) (actual time=0.089..0.089 rows=364 loops=1)"
"                                                                    Index Cond: (iin.dept_cd_id = item_dept_cd.dept_cd_id)"
"                                                              ->  Bitmap Index Scan on item_item_num_division_key  (cost=0.00..59.64 rows=2573 width=0) (actual time=0.479..0.479 rows=2753 loops=1)"
"                                                                    Index Cond: ((iin.division)::text = 'BSM'::text)"
"                                            ->  Index Scan using item_sku_item_num_id_key on item_sku iis  (cost=0.00..15.82 rows=1 width=32) (actual time=0.015..0.074 rows=24 loops=360)"
"                                                  Index Cond: (iis.item_num_id = iin.item_num_id)"
"                                                  Filter: ((iis.division)::text = 'BSM'::text)"
"                                      ->  Index Scan using ord_line_item_id_idx on ord_line  (cost=0.00..71.79 rows=3 width=16) (actual time=0.009..0.072 rows=13 loops=8463)"
"                                            Index Cond: (ord_line.item_id = iis.item_id)"
"                                            Filter: ((ord_line.division)::text = 'BSM'::text)"
"                    ->  Index Scan using item_class_cd_pkey on item_class_cd  (cost=0.00..0.27 rows=1 width=31) (actual time=0.001..0.001 rows=0 loops=5118)"
"                          Index Cond: (iin.class_cd_id = item_class_cd.class_cd_id)"
"                          Filter: ((item_class_cd.division)::text = 'BSM'::text)"
"              ->  Index Scan using item_size_cd_pkey on item_size_cd  (cost=0.00..0.27 rows=1 width=25) (actual time=0.003..0.004 rows=1 loops=5118)"
"                    Index Cond: (iis.size_cd_id = item_size_cd.size_cd_id)"
"                    Filter: ((item_size_cd.division)::text = 'BSM'::text)"
"        ->  Index Scan using item_color_cd_pkey on item_color_cd  (cost=0.00..0.27 rows=1 width=25) (actual time=0.003..0.004 rows=1 loops=5118)"
"              Index Cond: (iis.color_cd_id = item_color_cd.color_cd_id)"
"              Filter: ((item_color_cd.division)::text = 'BSM'::text)"
"Total runtime: 3208.876 ms"

查询只有更改为WHERE DATE(trans_date)BETWEEN’2012-04-01’和’2012-04-17′

SELECT   trans_date                                   AS order_date,iin.item_num                                           AS item_num,color_cd                                               AS color_code,color_desc                                             AS color_description,size_cd                                                AS size_code,size_desc                                              AS size_description,class_cd                                               AS class_code,class_desc                                             AS class_description,dept_cd                                                AS dept_code,dept_desc                                              AS dept_description,Count(ord_id)                                          AS num_of_orders,Sum(vs.qty_ordered)                                    AS units,To_char(Sum(merch_amt_new3),'99G999G990.00')           AS merch_amt,To_char(Sum(gift_cert_new3 - gift_cert_canceled_new3),'99G999G990.00') AS gift_cert,To_char(Sum(discount_amt),'99G999G990.00')             AS discount_amt,To_char(Sum(tax_amt),'99G999G990.00')                  AS tax,To_char(Sum(vs.qty_ordered * Coalesce(iis.cost,iin.cost)),'99G999G990.00') AS extended_cost,To_char(Sum(merch_amt - discount_amt),'99G999G990.00') AS total,To_char(Sum(canceled_merch_new3),'99G999G990.00')      AS canceled_merch,iis.sku_id
FROM     (SELECT   oh.division,oh.ord_id,client_order_num,source_id,bus_type_id,order_type_id,Date(ls.trans_date) AS trans_date,ls.ord_line_id,Sum(ls.qty_ordered) AS qty_ordered,Sum(ls.amount)         AS merch_amt,Sum(tax)  AS tax_amt,Coalesce((SELECT Sum(ledger_discount.amount) AS SUM
                             FROM   ledger_discount
                             WHERE  ledger_discount.ledger_code ~~ 'D%'
                                    AND ledger_discount.division = oh.division
                                    AND ledger_discount.ord_id = oh.ord_id
                                    AND ledger_discount.ord_line_id = ls.ord_line_id
                                    AND Date(ledger_discount.trans_date) = Date(ls.trans_date)),0.0) AS discount_amt,(CASE
                      WHEN ls.ledger_code = 'DO'
                      THEN Sum(ls.amount)
                      ELSE 0.0
                    END) AS merch_amt_new3,(CASE
                      WHEN ls.ledger_code = 'DOG'
                      THEN Sum(ls.amount)
                      ELSE 0.0
                    END) AS gift_cert_new3,(CASE
                      WHEN ls.ledger_code = 'DCG'
                      THEN Sum(-ls.amount)
                      ELSE 0.0
                    END) AS gift_cert_canceled_new3,(CASE
                      WHEN ls.ledger_code = 'DC'
                      THEN Sum(-ls.amount)
                      ELSE 0.0
                    END) AS canceled_merch_new3
          FROM     ledger_demand ls
                   JOIN ord_header oh
                     USING(division,ord_id)
          WHERE    (ls.qty_ordered > 0
                    AND ls.ledger_code ~~ 'D%')
                    OR (ls.ledger_code ~~ 'DC%')
          GROUP BY oh.division,ls.trans_date,ls.ledger_code
                   ) AS vs
         JOIN ord_line
           USING(division,ord_id,ord_line_id)
         JOIN item_sku AS iis
           USING(division,item_id)
         JOIN item_item_num AS iin
           USING(division,item_num_id)
         LEFT JOIN item_color_cd
          USING(division,color_cd_id)
         LEFT JOIN item_size_cd
           USING(division,size_cd_id)
         LEFT JOIN item_class_cd
           USING(division,class_cd_id)
         LEFT JOIN item_dept_cd
           USING(division,dept_cd_id)
WHERE DATE(trans_date) BETWEEN '2012-04-01' AND '2012-04-17' 
AND item_dept_cd.dept_cd LIKE 'S'
AND division = 'BSM' 
GROUP BY trans_date,iin.item_num,color_cd,color_desc,size_cd,size_desc,class_cd,class_desc,dept_cd,dept_desc,iis.sku_id

简短的答案是它真的取决于你的数据集/表/索引等.尝试为你的每个语句运行 EXPLAIN,它会告诉你究竟发生了什么.

EXPLAIN SELECT * FROM myTable WHERE myDate BETWEEN '2012-01-01' AND '2012-01-04'

EXPLAIN SELECT * FROM myTable WHERE myDate BETWEEN '2012-01-01' AND '2012-04-17'

（编辑：李大同）

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