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Hi all,
Please see this case.
TPC-DS query 95:
with ws_wh as
(select ws1.ws_order_number,ws1.ws_warehouse_sk wh1,ws2.ws_warehouse_sk wh2
from web_sales ws1,web_sales ws2
where ws1.ws_order_number = ws2.ws_order_number
and ws1.ws_warehouse_sk <> ws2.ws_warehouse_sk)
select
count(distinct ws_order_number) as "order count"
,sum(ws_ext_ship_cost) as "total shipping cost"
,sum(ws_net_profit) as "total net profit"
from
web_sales ws1
,date_dim
,customer_address
,web_site
where
d_date between '1999-5-01' and
(cast('1999-5-01' as date) + interval '60 days')
and ws1.ws_ship_date_sk = d_date_sk
and ws1.ws_ship_addr_sk = ca_address_sk
and ca_state = 'TX'
and ws1.ws_web_site_sk = web_site_sk
and web_company_name = 'pri'
and ws1.ws_order_number in (select ws_order_number
from ws_wh)
and ws1.ws_order_number in (select wr_order_number
from web_returns,ws_wh
where wr_order_number = ws_wh.ws_order_number)
order by count(distinct ws_order_number)
limit 100;
Its execution time is nearly 1 min:
QUERY PLAN
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Limit (cost=771620.21..771620.21 rows=1 width=72) (actual time=56669.478..56669.563 rows=1 loops=1)
CTE ws_wh
-> Hash Join (cost=37772.14..198810.77 rows=7242361 width=12) (actual time=211.161..1443.926 rows=6644004 loops=1)
Hash Cond: (ws1_1.ws_order_number = ws2.ws_order_number)
Join Filter: (ws1_1.ws_warehouse_sk <> ws2.ws_warehouse_sk)
Rows Removed by Join Filter: 2381030
-> Seq Scan on web_sales ws1_1 (cost=0.00..25968.84 rows=719384 width=8) (actual time=0.014..106.870 rows=719384 loops=1)
-> Hash (cost=25968.84..25968.84 rows=719384 width=8) (actual time=210.247..210.248 rows=719384 loops=1)
Buckets: 262144 Batches: 8 Memory Usage: 5563kB
-> Seq Scan on web_sales ws2 (cost=0.00..25968.84 rows=719384 width=8) (actual time=0.005..111.802 rows=719384 loops=1)
-> Sort (cost=572809.44..572809.45 rows=1 width=72) (actual time=56669.477..56669.559 rows=1 loops=1)
Sort Key: (count(DISTINCT ws1.ws_order_number))
Sort Method: quicksort Memory: 25kB
-> Aggregate (cost=572809.42..572809.43 rows=1 width=72) (actual time=56669.456..56669.538 rows=1 loops=1)
-> Sort (cost=572809.37..572809.38 rows=5 width=16) (actual time=56669.424..56669.510 rows=121 loops=1)
Sort Key: ws1.ws_order_number
Sort Method: quicksort Memory: 29kB
-> Nested Loop Semi Join (cost=390001.60..572809.31 rows=5 width=16) (actual time=5814.554..56669.277 rows=121 loops=1)
Join Filter: (ws1.ws_order_number = ws_wh.ws_order_number)
Rows Removed by Join Filter: 400808138
-> Hash Join (cost=390001.60..414560.96 rows=5 width=24) (actual time=4939.833..4940.928 rows=121 loops=1)
Hash Cond: (ws1.ws_order_number = web_returns.wr_order_number)
-> Gather (cost=1003.03..25562.31 rows=8 width=16) (actual time=2.891..3.674 rows=148 loops=1)
Workers Planned: 2
Workers Launched: 2
-> Nested Loop (cost=3.03..24561.51 rows=3 width=16) (actual time=4.531..75.030 rows=49 loops=3)
-> Nested Loop (cost=2.74..24548.21 rows=42 width=20) (actual time=1.566..72.683 rows=584 loops=3)
-> Hash Join (cost=2.44..22672.82 rows=49957 width=24) (actual time=0.158..58.416 rows=31830 loops=3)
Hash Cond: (ws1.ws_web_site_sk = web_site.web_site_sk)
-> Parallel Seq Scan on web_sales ws1 (cost=0.00..21772.43 rows=299743 width=28) (actual time=0.054..24.308 rows=239795 loops=3)
-> Hash (cost=2.38..2.38 rows=5 width=4) (actual time=0.047..0.047 rows=5 loops=3)
Buckets: 1024 Batches: 1 Memory Usage: 9kB
-> Seq Scan on web_site (cost=0.00..2.38 rows=5 width=4) (actual time=0.036..0.042 rows=5 loops=3)
Filter: (web_company_name = 'pri'::bpchar)
Rows Removed by Filter: 25
-> Memoize (cost=0.30..0.33 rows=1 width=4) (actual time=0.000..0.000 rows=0 loops=95491)
Cache Key: ws1.ws_ship_date_sk
Cache Mode: logical
Hits: 67 Misses: 413 Evictions: 0 Overflows: 0 Memory Usage: 28kB
Worker 0: Hits: 44145 Misses: 1934 Evictions: 0 Overflows: 0 Memory Usage: 131kB
Worker 1: Hits: 46993 Misses: 1939 Evictions: 0 Overflows: 0 Memory Usage: 131kB
-> Index Scan using date_dim_pkey on date_dim (cost=0.29..0.32 rows=1 width=4) (actual time=0.003..0.003 rows=0 loops=4286)
Index Cond: (d_date_sk = ws1.ws_ship_date_sk)
Filter: ((d_date >= '1999-05-01'::date) AND (d_date <= '1999-06-30 00:00:00'::timestamp without time zone))
Rows Removed by Filter: 1
-> Index Scan using customer_address_pkey on customer_address (cost=0.29..0.32 rows=1 width=4) (actual time=0.004..0.004 rows=0 loops=1752)
Index Cond: (ca_address_sk = ws1.ws_ship_addr_sk)
Filter: (ca_state = 'TX'::bpchar)
Rows Removed by Filter: 1
-> Hash (cost=388535.46..388535.46 rows=37049 width=8) (actual time=4936.733..4936.734 rows=42249 loops=1)
Buckets: 65536 Batches: 1 Memory Usage: 2163kB
-> HashAggregate (cost=388164.97..388535.46 rows=37049 width=8) (actual time=4926.772..4931.933 rows=42249 loops=1)
Group Key: web_returns.wr_order_number
Batches: 1 Memory Usage: 3345kB
-> Hash Join (cost=2942.67..365438.21 rows=9090701 width=8) (actual time=230.033..4014.732 rows=8677946 loops=1)
Hash Cond: (ws_wh_1.ws_order_number = web_returns.wr_order_number)
-> CTE Scan on ws_wh ws_wh_1 (cost=0.00..144847.22 rows=7242361 width=4) (actual time=211.163..2765.479 rows=6644004 loops=1)
-> Hash (cost=2045.63..2045.63 rows=71763 width=4) (actual time=18.445..18.445 rows=71763 loops=1)
Buckets: 131072 Batches: 1 Memory Usage: 3547kB
-> Seq Scan on web_returns (cost=0.00..2045.63 rows=71763 width=4) (actual time=0.025..10.838 rows=71763 loops=1)
-> CTE Scan on ws_wh (cost=0.00..144847.22 rows=7242361 width=4) (actual time=0.002..232.953 rows=3312465 loops=121)
Planning Time: 2.967 ms
Execution Time: 56689.671 ms
(63 rows)
If applying this patch:
diff --git a/src/backend/optimizer/plan/analyzejoins.c b/src/backend/optimizer/plan/analyzejoins.c
index c3fd4a81f8..c99282cda6 100644
--- a/src/backend/optimizer/plan/analyzejoins.c
+++ b/src/backend/optimizer/plan/analyzejoins.c
@@ -1231,7 +1231,7 @@ innerrel_is_unique(PlannerInfo *root,
}
/* No cached information, so try to make the proof. */
- if (is_innerrel_unique_for(root, joinrelids, outerrelids, innerrel,
+ if (!is_innerrel_unique_for(root, joinrelids, outerrelids, innerrel,
jointype, restrictlist))
{
/*
The execution time is reduced to 6 seconds:
QUERY PLAN
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Limit (cost=441755.76..441755.77 rows=1 width=72) (actual time=6508.013..6508.256 rows=1 loops=1)
CTE ws_wh
-> Hash Join (cost=37772.14..74062.53 rows=7095248 width=12) (actual time=203.407..560.264 rows=719205 loops=1)
Hash Cond: (ws1_1.ws_order_number = ws2.ws_order_number)
Join Filter: (ws1_1.ws_warehouse_sk <> ws2.ws_warehouse_sk)
Rows Removed by Join Filter: 255623
-> Seq Scan on web_sales ws1_1 (cost=0.00..25968.84 rows=719384 width=8) (actual time=0.021..95.808 rows=719384 loops=1)
-> Hash (cost=25968.84..25968.84 rows=719384 width=8) (actual time=202.456..202.457 rows=719384 loops=1)
Buckets: 262144 Batches: 8 Memory Usage: 5563kB
-> Seq Scan on web_sales ws2 (cost=0.00..25968.84 rows=719384 width=8) (actual time=0.017..105.868 rows=719384 loops=1)
-> Sort (cost=367693.24..367693.24 rows=1 width=72) (actual time=6508.012..6508.252 rows=1 loops=1)
Sort Key: (count(DISTINCT ws1.ws_order_number))
Sort Method: quicksort Memory: 25kB
-> Aggregate (cost=367693.22..367693.23 rows=1 width=72) (actual time=6507.989..6508.230 rows=1 loops=1)
-> Sort (cost=367693.16..367693.18 rows=5 width=16) (actual time=6507.943..6508.189 rows=121 loops=1)
Sort Key: ws1.ws_order_number
Sort Method: quicksort Memory: 29kB
-> Nested Loop Semi Join (cost=189126.19..367693.11 rows=5 width=16) (actual time=998.191..6508.088 rows=121 loops=1)
Join Filter: (ws1.ws_order_number = ws_wh.ws_order_number)
Rows Removed by Join Filter: 43344728
-> Nested Loop (cost=189126.19..212112.41 rows=5 width=24) (actual time=909.308..911.031 rows=121 loops=1)
Join Filter: (web_site.web_site_sk = ws1.ws_web_site_sk)
Rows Removed by Join Filter: 4359
-> Hash Join (cost=189126.19..212107.84 rows=29 width=28) (actual time=909.243..910.378 rows=896 loops=1)
Hash Cond: (ws1.ws_order_number = web_returns.wr_order_number)
-> Gather (cost=3050.28..26031.49 rows=45 width=20) (actual time=10.506..11.281 rows=1103 loops=1)
Workers Planned: 2
Workers Launched: 2
-> Nested Loop (cost=2050.28..25026.99 rows=19 width=20) (actual time=8.162..64.689 rows=368 loops=3)
-> Parallel Hash Join (cost=2049.99..24947.90 rows=242 width=24) (actual time=6.293..52.376 rows=4465 loops=3)
Hash Cond: (ws1.ws_ship_date_sk = date_dim.d_date_sk)
-> Parallel Seq Scan on web_sales ws1 (cost=0.00..21772.43 rows=299743 width=28) (actual time=0.024..24.598 rows=239795 loops=3)
-> Parallel Hash (cost=2049.55..2049.55 rows=35 width=4) (actual time=5.895..5.896 rows=20 loops=3)
Buckets: 1024 Batches: 1 Memory Usage: 40kB
-> Parallel Seq Scan on date_dim (cost=0.00..2049.55 rows=35 width=4) (actual time=4.855..5.816 rows=20 loops=3)
Filter: ((d_date >= '1999-05-01'::date) AND (d_date <= '1999-06-30 00:00:00'::timestamp without time zone))
Rows Removed by Filter: 24329
-> Index Scan using customer_address_pkey on customer_address (cost=0.29..0.32 rows=1 width=4) (actual time=0.003..0.003 rows=0 loops=13394)
Index Cond: (ca_address_sk = ws1.ws_ship_addr_sk)
Filter: (ca_state = 'TX'::bpchar)
Rows Removed by Filter: 1
-> Hash (cost=185612.75..185612.75 rows=37053 width=8) (actual time=898.519..898.521 rows=42249 loops=1)
Buckets: 65536 Batches: 1 Memory Usage: 2163kB
-> HashAggregate (cost=185242.22..185612.75 rows=37053 width=8) (actual time=888.235..893.423 rows=42249 loops=1)
Group Key: web_returns.wr_order_number
Batches: 1 Memory Usage: 3345kB
-> Hash Join (cost=2942.67..163474.00 rows=8707289 width=8) (actual time=223.693..825.681 rows=518567 loops=1)
Hash Cond: (ws_wh_1.ws_order_number = web_returns.wr_order_number)
-> CTE Scan on ws_wh ws_wh_1 (cost=0.00..141904.96 rows=7095248 width=4) (actual time=203.411..706.045 rows=719205 loops=1)
-> Hash (cost=2045.63..2045.63 rows=71763 width=4) (actual time=19.983..19.983 rows=71763 loops=1)
Buckets: 131072 Batches: 1 Memory Usage: 3547kB
-> Seq Scan on web_returns (cost=0.00..2045.63 rows=71763 width=4) (actual time=0.026..12.516 rows=71763 loops=1)
-> Materialize (cost=0.00..2.40 rows=5 width=4) (actual time=0.000..0.000 rows=5 loops=896)
-> Seq Scan on web_site (cost=0.00..2.38 rows=5 width=4) (actual time=0.046..0.052 rows=5 loops=1)
Filter: (web_company_name = 'pri'::bpchar)
Rows Removed by Filter: 25
-> CTE Scan on ws_wh (cost=0.00..141904.96 rows=7095248 width=4) (actual time=0.001..25.301 rows=358222 loops=121)
Planning Time: 3.432 ms
Execution Time: 6512.766 ms
(59 rows)
The difference between both query plans is the second one uses Materialize instead of Memoize. From the code, it seems that changing the usage of the cache brings performance improvement unexpectedly.
Environment:
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(at)127(dot)0(dot)0(dot)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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