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Hi all,
Please see this case:
Query 4 on TPC-DS benchmark:
with year_total as (
select c_customer_id customer_id
,c_first_name customer_first_name
,c_last_name customer_last_name
,c_preferred_cust_flag customer_preferred_cust_flag
,c_birth_country customer_birth_country
,c_login customer_login
,c_email_address customer_email_address
,d_year dyear
,sum(((ss_ext_list_price-ss_ext_wholesale_cost-ss_ext_discount_amt)+ss_ext_sales_price)/2) year_total
,'s' sale_type
from customer
,store_sales
,date_dim
where c_customer_sk = ss_customer_sk
and ss_sold_date_sk = d_date_sk
group by c_customer_id
,c_first_name
,c_last_name
,c_preferred_cust_flag
,c_birth_country
,c_login
,c_email_address
,d_year
union all
select c_customer_id customer_id
,c_first_name customer_first_name
,c_last_name customer_last_name
,c_preferred_cust_flag customer_preferred_cust_flag
,c_birth_country customer_birth_country
,c_login customer_login
,c_email_address customer_email_address
,d_year dyear
,sum((((cs_ext_list_price-cs_ext_wholesale_cost-cs_ext_discount_amt)+cs_ext_sales_price)/2) ) year_total
,'c' sale_type
from customer
,catalog_sales
,date_dim
where c_customer_sk = cs_bill_customer_sk
and cs_sold_date_sk = d_date_sk
group by c_customer_id
,c_first_name
,c_last_name
,c_preferred_cust_flag
,c_birth_country
,c_login
,c_email_address
,d_year
union all
select c_customer_id customer_id
,c_first_name customer_first_name
,c_last_name customer_last_name
,c_preferred_cust_flag customer_preferred_cust_flag
,c_birth_country customer_birth_country
,c_login customer_login
,c_email_address customer_email_address
,d_year dyear
,sum((((ws_ext_list_price-ws_ext_wholesale_cost-ws_ext_discount_amt)+ws_ext_sales_price)/2) ) year_total
,'w' sale_type
from customer
,web_sales
,date_dim
where c_customer_sk = ws_bill_customer_sk
and ws_sold_date_sk = d_date_sk
group by c_customer_id
,c_first_name
,c_last_name
,c_preferred_cust_flag
,c_birth_country
,c_login
,c_email_address
,d_year
)
select
t_s_secyear.customer_id
,t_s_secyear.customer_first_name
,t_s_secyear.customer_last_name
,t_s_secyear.customer_email_address
from year_total t_s_firstyear
,year_total t_s_secyear
,year_total t_c_firstyear
,year_total t_c_secyear
,year_total t_w_firstyear
,year_total t_w_secyear
where t_s_secyear.customer_id = t_s_firstyear.customer_id
and t_s_firstyear.customer_id = t_c_secyear.customer_id
and t_s_firstyear.customer_id = t_c_firstyear.customer_id
and t_s_firstyear.customer_id = t_w_firstyear.customer_id
and t_s_firstyear.customer_id = t_w_secyear.customer_id
and t_s_firstyear.sale_type = 's'
and t_c_firstyear.sale_type = 'c'
and t_w_firstyear.sale_type = 'w'
and t_s_secyear.sale_type = 's'
and t_c_secyear.sale_type = 'c'
and t_w_secyear.sale_type = 'w'
and t_s_firstyear.dyear = 2001
and t_s_secyear.dyear = 2001+1
and t_c_firstyear.dyear = 2001
and t_c_secyear.dyear = 2001+1
and t_w_firstyear.dyear = 2001
and t_w_secyear.dyear = 2001+1
and t_s_firstyear.year_total > 0
and t_c_firstyear.year_total > 0
and t_w_firstyear.year_total > 0
and case when t_c_firstyear.year_total > 0 then t_c_secyear.year_total / t_c_firstyear.year_total else null end
> case when t_s_firstyear.year_total > 0 then t_s_secyear.year_total / t_s_firstyear.year_total else null end
and case when t_c_firstyear.year_total > 0 then t_c_secyear.year_total / t_c_firstyear.year_total else null end
> case when t_w_firstyear.year_total > 0 then t_w_secyear.year_total / t_w_firstyear.year_total else null end
order by t_s_secyear.customer_id
,t_s_secyear.customer_first_name
,t_s_secyear.customer_last_name
,t_s_secyear.customer_email_address
limit 100;
The execution time is more than 50 minutes:
QUERY PLAN
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Limit (cost=1255378.56..1255378.57 rows=1 width=132) (actual time=3024403.311..3024403.342 rows=8 loops=1)
CTE year_total
-> Append (cost=197433.23..461340.62 rows=5041142 width=216) (actual time=4126.043..7897.747 rows=384208 loops=1)
-> HashAggregate (cost=197433.23..233436.60 rows=2880270 width=216) (actual time=4126.042..4231.703 rows=190581 loops=1)
Group Key: customer.c_customer_id, customer.c_first_name, customer.c_last_name, customer.c_preferred_cust_flag, customer.c_birth_country, customer.c_login, customer.c_email_address, date_dim.d_year
Batches: 1 Memory Usage: 213017kB
-> Hash Join (cost=8151.60..103824.45 rows=2880270 width=174) (actual time=69.110..1686.608 rows=2685453 loops=1)
Hash Cond: (store_sales.ss_sold_date_sk = date_dim.d_date_sk)
-> Hash Join (cost=5103.00..93214.72 rows=2880270 width=174) (actual time=49.517..1162.567 rows=2750652 loops=1)
Hash Cond: (store_sales.ss_customer_sk = customer.c_customer_sk)
-> Seq Scan on store_sales (cost=0.00..80550.70 rows=2880270 width=30) (actual time=0.018..208.022 rows=2880404 loops=1)
-> Hash (cost=3853.00..3853.00 rows=100000 width=152) (actual time=49.271..49.271 rows=100000 loops=1)
Buckets: 131072 Batches: 1 Memory Usage: 17161kB
-> Seq Scan on customer (cost=0.00..3853.00 rows=100000 width=152) (actual time=0.011..26.448 rows=100000 loops=1)
-> Hash (cost=2135.49..2135.49 rows=73049 width=8) (actual time=19.369..19.370 rows=73049 loops=1)
Buckets: 131072 Batches: 1 Memory Usage: 3878kB
-> Seq Scan on date_dim (cost=0.00..2135.49 rows=73049 width=8) (actual time=0.037..11.763 rows=73049 loops=1)
-> HashAggregate (cost=114410.03..132428.63 rows=1441488 width=216) (actual time=2369.202..2447.868 rows=136978 loops=1)
Group Key: customer_1.c_customer_id, customer_1.c_first_name, customer_1.c_last_name, customer_1.c_preferred_cust_flag, customer_1.c_birth_country, customer_1.c_login, customer_1.c_email_address, date_dim_1.d_year
Batches: 1 Memory Usage: 131097kB
-> Hash Join (cost=8151.60..67561.67 rows=1441488 width=177) (actual time=62.483..974.143 rows=1430939 loops=1)
Hash Cond: (catalog_sales.cs_sold_date_sk = date_dim_1.d_date_sk)
-> Hash Join (cost=5103.00..60728.94 rows=1441488 width=177) (actual time=46.571..687.972 rows=1434519 loops=1)
Hash Cond: (catalog_sales.cs_bill_customer_sk = customer_1.c_customer_sk)
-> Seq Scan on catalog_sales (cost=0.00..51841.88 rows=1441488 width=33) (actual time=0.029..128.238 rows=1441548 loops=1)
-> Hash (cost=3853.00..3853.00 rows=100000 width=152) (actual time=46.311..46.325 rows=100000 loops=1)
Buckets: 131072 Batches: 1 Memory Usage: 17161kB
-> Seq Scan on customer customer_1 (cost=0.00..3853.00 rows=100000 width=152) (actual time=0.005..23.350 rows=100000 loops=1)
-> Hash (cost=2135.49..2135.49 rows=73049 width=8) (actual time=15.677..15.677 rows=73049 loops=1)
Buckets: 131072 Batches: 1 Memory Usage: 3878kB
-> Seq Scan on date_dim date_dim_1 (cost=0.00..2135.49 rows=73049 width=8) (actual time=0.015..7.957 rows=73049 loops=1)
-> HashAggregate (cost=61277.38..70269.68 rows=719384 width=216) (actual time=1166.953..1198.730 rows=56649 loops=1)
Group Key: customer_2.c_customer_id, customer_2.c_first_name, customer_2.c_last_name, customer_2.c_preferred_cust_flag, customer_2.c_birth_country, customer_2.c_login, customer_2.c_email_address, date_dim_2.d_year
Batches: 1 Memory Usage: 57369kB
-> Hash Join (cost=8151.60..37897.40 rows=719384 width=177) (actual time=68.327..508.594 rows=719119 loops=1)
Hash Cond: (web_sales.ws_sold_date_sk = date_dim_2.d_date_sk)
-> Hash Join (cost=5103.00..32960.30 rows=719384 width=177) (actual time=52.240..357.963 rows=719217 loops=1)
Hash Cond: (web_sales.ws_bill_customer_sk = customer_2.c_customer_sk)
-> Seq Scan on web_sales (cost=0.00..25968.84 rows=719384 width=33) (actual time=0.032..62.464 rows=719384 loops=1)
-> Hash (cost=3853.00..3853.00 rows=100000 width=152) (actual time=51.959..51.960 rows=100000 loops=1)
Buckets: 131072 Batches: 1 Memory Usage: 17161kB
-> Seq Scan on customer customer_2 (cost=0.00..3853.00 rows=100000 width=152) (actual time=0.004..25.350 rows=100000 loops=1)
-> Hash (cost=2135.49..2135.49 rows=73049 width=8) (actual time=15.831..15.834 rows=73049 loops=1)
Buckets: 131072 Batches: 1 Memory Usage: 3878kB
-> Seq Scan on date_dim date_dim_2 (cost=0.00..2135.49 rows=73049 width=8) (actual time=0.014..8.100 rows=73049 loops=1)
-> Sort (cost=794037.94..794037.95 rows=1 width=132) (actual time=3024403.310..3024403.313 rows=8 loops=1)
Sort Key: t_s_secyear.customer_id, t_s_secyear.customer_first_name, t_s_secyear.customer_last_name, t_s_secyear.customer_email_address
Sort Method: quicksort Memory: 26kB
-> Nested Loop (cost=0.00..794037.93 rows=1 width=132) (actual time=354851.431..3024403.218 rows=8 loops=1)
Join Filter: ((t_s_secyear.customer_id = t_w_secyear.customer_id) AND (CASE WHEN (t_c_firstyear.year_total > '0'::numeric) THEN (t_c_secyear.year_total / t_c_firstyear.year_total) ELSE NULL::numeric END > CASE WHEN (t_w_firstyear.year_total >
'0'::numeric) THEN (t_w_secyear.year_total / t_w_firstyear.year_total) ELSE NULL::numeric END))
Rows Removed by Join Filter: 810136
-> Nested Loop (cost=0.00..668006.23 rows=1 width=308) (actual time=33554.075..3021248.646 rows=72 loops=1)
Join Filter: ((t_s_secyear.customer_id = t_c_secyear.customer_id) AND (CASE WHEN (t_c_firstyear.year_total > '0'::numeric) THEN (t_c_secyear.year_total / t_c_firstyear.year_total) ELSE NULL::numeric END > CASE WHEN (t_s_firstyear.year_total
> '0'::numeric) THEN (t_s_secyear.year_total / t_s_firstyear.year_total) ELSE NULL::numeric END))
Rows Removed by Join Filter: 11876277
-> Nested Loop (cost=0.00..541974.53 rows=1 width=320) (actual time=14866.104..3001271.961 rows=437 loops=1)
Join Filter: (t_s_firstyear.customer_id = t_s_secyear.customer_id)
Rows Removed by Join Filter: 44702488
-> Nested Loop (cost=0.00..415941.57 rows=2 width=156) (actual time=11739.944..2946020.749 rows=1171 loops=1)
Join Filter: (t_s_firstyear.customer_id = t_w_firstyear.customer_id)
Rows Removed by Join Filter: 112695277
-> Nested Loop (cost=0.00..277302.08 rows=9 width=104) (actual time=8139.729..2351733.795 rows=9952 loops=1)
Join Filter: (t_s_firstyear.customer_id = t_c_firstyear.customer_id)
Rows Removed by Join Filter: 997895870
-> CTE Scan on year_total t_s_firstyear (cost=0.00..138631.41 rows=42 width=52) (actual time=4126.046..4234.598 rows=37923 loops=1)
Filter: ((year_total > '0'::numeric) AND (sale_type = 's'::text) AND (dyear = 2001))
Rows Removed by Filter: 346285
-> CTE Scan on year_total t_c_firstyear (cost=0.00..138631.41 rows=42 width=52) (actual time=28.926..60.356 rows=26314 loops=37923)
Filter: ((year_total > '0'::numeric) AND (sale_type = 'c'::text) AND (dyear = 2001))
Rows Removed by Filter: 357894
-> CTE Scan on year_total t_w_firstyear (cost=0.00..138631.41 rows=42 width=52) (actual time=49.572..59.057 rows=11324 loops=9952)
Filter: ((year_total > '0'::numeric) AND (sale_type = 'w'::text) AND (dyear = 2001))
Rows Removed by Filter: 372884
-> CTE Scan on year_total t_s_secyear (cost=0.00..126028.55 rows=126 width=164) (actual time=0.002..44.949 rows=38175 loops=1171)
Filter: ((sale_type = 's'::text) AND (dyear = 2002))
Rows Removed by Filter: 346033
-> CTE Scan on year_total t_c_secyear (cost=0.00..126028.55 rows=126 width=52) (actual time=21.023..44.097 rows=27177 loops=437)
Filter: ((sale_type = 'c'::text) AND (dyear = 2002))
Rows Removed by Filter: 357031
-> CTE Scan on year_total t_w_secyear (cost=0.00..126028.55 rows=126 width=52) (actual time=36.137..43.090 rows=11252 loops=72)
Filter: ((sale_type = 'w'::text) AND (dyear = 2002))
Rows Removed by Filter: 372956
Planning Time: 4.529 ms
Execution Time: 3024486.695 ms
(83 rows)
If we disable this checking:
diff --git a/src/backend/optimizer/util/pathnode.c b/src/backend/optimizer/util/pathnode.c
index c42742d2c7..d47d0f0e59 100644
--- a/src/backend/optimizer/util/pathnode.c
+++ b/src/backend/optimizer/util/pathnode.c
@@ -555,16 +555,6 @@ add_path(RelOptInfo *parent_rel, Path *new_path)
}
break;
case COSTS_BETTER2:
- if (keyscmp != PATHKEYS_BETTER1)
- {
- outercmp = bms_subset_compare(PATH_REQ_OUTER(new_path),
- PATH_REQ_OUTER(old_path));
- if ((outercmp == BMS_EQUAL ||
- outercmp == BMS_SUBSET2) &&
- new_path->rows >= old_path->rows &&
- new_path->parallel_safe <= old_path->parallel_safe)
- accept_new = false; /* old dominates new */
- }
break;
case COSTS_DIFFERENT:
The execution time is reduced to around 8 seconds:
QUERY PLAN
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Limit (cost=1255392.10..1255392.10 rows=1 width=132) (actual time=8068.870..8068.887 rows=8 loops=1)
CTE year_total
-> Append (cost=197441.91..461358.17 rows=5041411 width=216) (actual time=4004.918..7547.884 rows=384208 loops=1)
-> HashAggregate (cost=197441.91..233447.56 rows=2880452 width=216) (actual time=4004.917..4112.220 rows=190581 loops=1)
Group Key: customer.c_customer_id, customer.c_first_name, customer.c_last_name, customer.c_preferred_cust_flag, customer.c_birth_country, customer.c_login, customer.c_email_address, date_dim.d_year
Batches: 1 Memory Usage: 213017kB
-> Hash Join (cost=8151.60..103827.22 rows=2880452 width=174) (actual time=73.291..1594.391 rows=2685453 loops=1)
Hash Cond: (store_sales.ss_sold_date_sk = date_dim.d_date_sk)
-> Hash Join (cost=5103.00..93217.01 rows=2880452 width=174) (actual time=52.407..1100.642 rows=2750652 loops=1)
Hash Cond: (store_sales.ss_customer_sk = customer.c_customer_sk)
-> Seq Scan on store_sales (cost=0.00..80552.52 rows=2880452 width=30) (actual time=0.017..213.629 rows=2880404 loops=1)
-> Hash (cost=3853.00..3853.00 rows=100000 width=152) (actual time=52.083..52.083 rows=100000 loops=1)
Buckets: 131072 Batches: 1 Memory Usage: 17161kB
-> Seq Scan on customer (cost=0.00..3853.00 rows=100000 width=152) (actual time=0.013..28.104 rows=100000 loops=1)
-> Hash (cost=2135.49..2135.49 rows=73049 width=8) (actual time=20.589..20.592 rows=73049 loops=1)
Buckets: 131072 Batches: 1 Memory Usage: 3878kB
-> Seq Scan on date_dim (cost=0.00..2135.49 rows=73049 width=8) (actual time=0.036..12.464 rows=73049 loops=1)
-> HashAggregate (cost=114414.19..132433.87 rows=1441575 width=216) (actual time=2186.304..2263.365 rows=136978 loops=1)
Group Key: customer_1.c_customer_id, customer_1.c_first_name, customer_1.c_last_name, customer_1.c_preferred_cust_flag, customer_1.c_birth_country, customer_1.c_login, customer_1.c_email_address, date_dim_1.d_year
Batches: 1 Memory Usage: 131097kB
-> Hash Join (cost=8151.60..67563.00 rows=1441575 width=177) (actual time=63.765..880.282 rows=1430939 loops=1)
Hash Cond: (catalog_sales.cs_sold_date_sk = date_dim_1.d_date_sk)
-> Hash Join (cost=5103.00..60730.04 rows=1441575 width=177) (actual time=47.735..619.585 rows=1434519 loops=1)
Hash Cond: (catalog_sales.cs_bill_customer_sk = customer_1.c_customer_sk)
-> Seq Scan on catalog_sales (cost=0.00..51842.75 rows=1441575 width=33) (actual time=0.033..121.738 rows=1441548 loops=1)
-> Hash (cost=3853.00..3853.00 rows=100000 width=152) (actual time=47.433..47.433 rows=100000 loops=1)
Buckets: 131072 Batches: 1 Memory Usage: 17161kB
-> Seq Scan on customer customer_1 (cost=0.00..3853.00 rows=100000 width=152) (actual time=0.004..23.960 rows=100000 loops=1)
-> Hash (cost=2135.49..2135.49 rows=73049 width=8) (actual time=15.755..15.756 rows=73049 loops=1)
Buckets: 131072 Batches: 1 Memory Usage: 3878kB
-> Seq Scan on date_dim date_dim_1 (cost=0.00..2135.49 rows=73049 width=8) (actual time=0.017..8.030 rows=73049 loops=1)
-> HashAggregate (cost=61277.38..70269.68 rows=719384 width=216) (actual time=1121.896..1152.982 rows=56649 loops=1)
Group Key: customer_2.c_customer_id, customer_2.c_first_name, customer_2.c_last_name, customer_2.c_preferred_cust_flag, customer_2.c_birth_country, customer_2.c_login, customer_2.c_email_address, date_dim_2.d_year
Batches: 1 Memory Usage: 57369kB
-> Hash Join (cost=8151.60..37897.40 rows=719384 width=177) (actual time=63.239..470.700 rows=719119 loops=1)
Hash Cond: (web_sales.ws_sold_date_sk = date_dim_2.d_date_sk)
-> Hash Join (cost=5103.00..32960.30 rows=719384 width=177) (actual time=47.365..329.499 rows=719217 loops=1)
Hash Cond: (web_sales.ws_bill_customer_sk = customer_2.c_customer_sk)
-> Seq Scan on web_sales (cost=0.00..25968.84 rows=719384 width=33) (actual time=0.036..60.068 rows=719384 loops=1)
-> Hash (cost=3853.00..3853.00 rows=100000 width=152) (actual time=47.076..47.078 rows=100000 loops=1)
Buckets: 131072 Batches: 1 Memory Usage: 17161kB
-> Seq Scan on customer customer_2 (cost=0.00..3853.00 rows=100000 width=152) (actual time=0.005..23.909 rows=100000 loops=1)
-> Hash (cost=2135.49..2135.49 rows=73049 width=8) (actual time=15.615..15.615 rows=73049 loops=1)
Buckets: 131072 Batches: 1 Memory Usage: 3878kB
-> Seq Scan on date_dim date_dim_2 (cost=0.00..2135.49 rows=73049 width=8) (actual time=0.019..8.060 rows=73049 loops=1)
-> Sort (cost=794033.93..794033.94 rows=1 width=132) (actual time=8068.869..8068.872 rows=8 loops=1)
Sort Key: t_s_secyear.customer_id, t_s_secyear.customer_first_name, t_s_secyear.customer_last_name, t_s_secyear.customer_email_address
Sort Method: quicksort Memory: 26kB
-> Hash Join (cost=794032.91..794033.92 rows=1 width=132) (actual time=8061.079..8068.861 rows=8 loops=1)
Hash Cond: (t_s_secyear.customer_id = t_s_firstyear.customer_id)
Join Filter: ((CASE WHEN (t_c_firstyear.year_total > '0'::numeric) THEN (t_c_secyear.year_total / t_c_firstyear.year_total) ELSE NULL::numeric END > CASE WHEN (t_s_firstyear.year_total > '0'::numeric) THEN (t_s_secyear.year_total / t_s_firstyear.year_total)
ELSE NULL::numeric END) AND (CASE WHEN (t_c_firstyear.year_total > '0'::numeric) THEN (t_c_secyear.year_total / t_c_firstyear.year_total) ELSE NULL::numeric END > CASE WHEN (t_w_firstyear.year_total > '0'::numeric) THEN (t_w_secyear.year_total / t_w_firstyear.year_total)
ELSE NULL::numeric END))
Rows Removed by Join Filter: 11
-> Merge Join (cost=390716.09..390717.01 rows=16 width=268) (actual time=7877.494..7885.971 rows=2793 loops=1)
Merge Cond: (t_s_secyear.customer_id = t_c_secyear.customer_id)
-> Sort (cost=126039.67..126039.99 rows=126 width=164) (actual time=7764.696..7768.885 rows=38175 loops=1)
Sort Key: t_s_secyear.customer_id
Sort Method: quicksort Memory: 7021kB
-> CTE Scan on year_total t_s_secyear (cost=0.00..126035.28 rows=126 width=164) (actual time=4004.934..7746.174 rows=38175 loops=1)
Filter: ((sale_type = 's'::text) AND (dyear = 2002))
Rows Removed by Filter: 346033
-> Sort (cost=264676.42..264676.48 rows=26 width=104) (actual time=112.790..113.328 rows=7188 loops=1)
Sort Key: t_c_firstyear.customer_id
Sort Method: quicksort Memory: 687kB
-> Hash Join (cost=138639.33..264675.81 rows=26 width=104) (actual time=83.825..109.977 rows=7188 loops=1)
Hash Cond: (t_c_secyear.customer_id = t_c_firstyear.customer_id)
-> CTE Scan on year_total t_c_secyear (cost=0.00..126035.28 rows=126 width=52) (actual time=20.337..42.859 rows=27177 loops=1)
Filter: ((sale_type = 'c'::text) AND (dyear = 2002))
Rows Removed by Filter: 357031
-> Hash (cost=138638.80..138638.80 rows=42 width=52) (actual time=63.460..63.461 rows=26314 loops=1)
Buckets: 32768 (originally 1024) Batches: 1 (originally 1) Memory Usage: 1725kB
-> CTE Scan on year_total t_c_firstyear (cost=0.00..138638.80 rows=42 width=52) (actual time=28.367..59.710 rows=26314 loops=1)
Filter: ((year_total > '0'::numeric) AND (sale_type = 'c'::text) AND (dyear = 2001))
Rows Removed by Filter: 357894
-> Hash (cost=403316.74..403316.74 rows=6 width=156) (actual time=182.649..182.650 rows=479 loops=1)
Buckets: 1024 Batches: 1 Memory Usage: 59kB
-> Merge Join (cost=403316.35..403316.74 rows=6 width=156) (actual time=177.380..182.540 rows=479 loops=1)
Merge Cond: (t_s_firstyear.customer_id = t_w_firstyear.customer_id)
-> Sort (cost=138639.93..138640.04 rows=42 width=52) (actual time=75.347..77.869 rows=37909 loops=1)
Sort Key: t_s_firstyear.customer_id
Sort Method: quicksort Memory: 3273kB
-> CTE Scan on year_total t_s_firstyear (cost=0.00..138638.80 rows=42 width=52) (actual time=0.002..60.630 rows=37923 loops=1)
Filter: ((year_total > '0'::numeric) AND (sale_type = 's'::text) AND (dyear = 2001))
Rows Removed by Filter: 346285
-> Sort (cost=264676.42..264676.48 rows=26 width=104) (actual time=102.001..102.053 rows=1306 loops=1)
Sort Key: t_w_firstyear.customer_id
Sort Method: quicksort Memory: 139kB
-> Hash Join (cost=138639.33..264675.81 rows=26 width=104) (actual time=93.653..101.516 rows=1306 loops=1)
Hash Cond: (t_w_secyear.customer_id = t_w_firstyear.customer_id)
-> CTE Scan on year_total t_w_secyear (cost=0.00..126035.28 rows=126 width=52) (actual time=33.759..40.504 rows=11252 loops=1)
Filter: ((sale_type = 'w'::text) AND (dyear = 2002))
Rows Removed by Filter: 372956
-> Hash (cost=138638.80..138638.80 rows=42 width=52) (actual time=59.875..59.875 rows=11324 loops=1)
Buckets: 16384 (originally 1024) Batches: 1 (originally 1) Memory Usage: 763kB
-> CTE Scan on year_total t_w_firstyear (cost=0.00..138638.80 rows=42 width=52) (actual time=48.632..58.272 rows=11324 loops=1)
Filter: ((year_total > '0'::numeric) AND (sale_type = 'w'::text) AND (dyear = 2001))
Rows Removed by Filter: 372884
Planning Time: 6.118 ms
Execution Time: 8179.205 ms
(98 rows)
The execution time is reduced by 99%. Similarly to my previous reports, I wonder if we can optimize the logic somewhere to improve the performance.
Environment:
The default configurations of PostgreSQL incur the error: "ERROR: could not resize shared memory segment "/PostgreSQL.3539600020" to 2097152 bytes: No space left on device"
Therefore, to run this query, I set up "work_mem = 1GB"
For the benchmark, I used 1 GB data, and my entire data folder can be downloaded here:
https://drive.google.com/file/d/1iK5gfyKudfn2BczpoZbNRY_IAD_rITZu/view?usp=sharing
The connection string is: postgresql://ubuntu:ubuntu@127.0.0.1:5432/tpcds"
tpch=# select version();
version
--------------------------------------------------------------------------------------------------
PostgreSQL 17.0 on x86_64-pc-linux-gnu, compiled by gcc (Ubuntu 13.2.0-23ubuntu4) 13.2.0, 64-bit
(1 row)
Best regards, Jinsheng Ba
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