Question

我在PostgreSQL 9.5中有以下查询，运行缓慢，测试fact表有22000行，store表295行和product表10行。

create table calc_base as
select a.ticket_id ticket_id, 
       b.product_id,  
       b.product_desc,
       a.promotion_flag promo_flag,
       sum(quantity) num_units,
       sum(sales) num_sales
from fact a
       inner join product b on a.product_id = b.product_id    
where store_id in (select store_id from store)
and b.product_id in (select product_id from fact 
                     group by 1 
                     order by count(distinct ticket_id) desc limit 5000) 
group by 1,2,3,4;

以下是此查询的索引列表：

--Add primary keys
ALTER TABLE  PRODUCT   ADD PRIMARY KEY (PRODUCT_ID);
ALTER TABLE  STORE   ADD PRIMARY KEY (STORE_ID);
ALTER TABLE  CUSTOMER   ADD PRIMARY KEY (CUSTOMER_ID);
ALTER TABLE  TIME   ADD PRIMARY KEY (DATE_ID); 

-- ADD FORIENG KEY without constraint
ALTER TABLE FACT ADD  FOREIGN KEY (PRODUCT_ID) REFERENCES PRODUCT (PRODUCT_ID);
ALTER TABLE FACT ADD  FOREIGN KEY (STORE_ID)   REFERENCES STORE (STORE_ID);
ALTER TABLE FACT ADD  FOREIGN KEY (DATE_ID)    REFERENCES TIME (DATE_ID);
ALTER TABLE FACT ADD  FOREIGN KEY (SEGMENT_ID) REFERENCES CUSTOMER (CUSTOMER_ID);

-- create indexes for forien keys
CREATE INDEX ON fact(PRODUCT_ID);
CREATE INDEX ON fact(STORE_ID);
CREATE INDEX ON fact(DATE_ID);

如何优化此查询以加快速度。我需要专业建议来优化聚合并在大数据集中分组，因为我的真实数据集有30亿个事务，我必须以30亿行运行此查询。

更新：

我使用更大的数据集where store_id in (select store_id from store) 200万行，fact 344117行，在没有product的情况下运行以下查询。

create table calc_base as
select a.ticket_id ticket_id,
    b.product_id, 
    b.product_desc,
    a.promotion_flag promo_flag,
    sum(quantity_abs) kpi_units,
    sum(sales_abs) kpi_sales
from fact a
    inner join product b on a.product_id = b.product_id    
where b.product_id in (select product_id from fact 
            group by 1 order by count(distinct ticket_id) desc limit 5000 ) 
group by 1,2,3,4;

查询计划：

"GroupAggregate  (cost=472629.13..505129.13 rows=1000000 width=39) (actual time=8230.069..11230.872 rows=2000000 loops=1)"
"  Group Key: a.ticket_id, b.product_id, b.product_desc, a.promotion_flag"
"  Buffers: shared hit=49090, temp read=19225 written=19225"
"  ->  Sort  (cost=472629.13..475129.13 rows=1000000 width=39) (actual time=8230.053..9771.612 rows=2000000 loops=1)"
"        Sort Key: a.ticket_id, b.product_id, b.product_desc, a.promotion_flag"
"        Sort Method: external merge  Disk: 98968kB"
"        Buffers: shared hit=49090, temp read=19225 written=19225"
"        ->  Hash Join  (cost=300396.32..357345.29 rows=1000000 width=39) (actual time=5424.131..6357.988 rows=2000000 loops=1)"
"              Hash Cond: (a.product_id = b.product_id)"
"              Buffers: shared hit=49076, temp read=6847 written=6847"
"              ->  Seq Scan on fact a  (cost=0.00..39449.00 rows=2000000 width=25) (actual time=0.009..129.726 rows=2000000 loops=1)"
"                    Buffers: shared hit=19449"
"              ->  Hash  (cost=298245.59..298245.59 rows=172058 width=26) (actual time=5423.385..5423.385 rows=914 loops=1)"
"                    Buckets: 262144  Batches: 1  Memory Usage: 2101kB"
"                    Buffers: shared hit=29627, temp read=6847 written=6847"
"                    ->  Hash Join  (cost=283334.26..298245.59 rows=172058 width=26) (actual time=5334.482..5423.097 rows=914 loops=1)"
"                          Hash Cond: (b.product_id = fact.product_id)"
"                          Buffers: shared hit=29627, temp read=6847 written=6847"
"                          ->  Seq Scan on product b  (cost=0.00..13616.17 rows=344117 width=20) (actual time=0.007..40.339 rows=344117 loops=1)"
"                                Buffers: shared hit=10175"
"                          ->  Hash  (cost=283328.34..283328.34 rows=473 width=6) (actual time=5334.458..5334.458 rows=914 loops=1)"
"                                Buckets: 1024  Batches: 1  Memory Usage: 51kB"
"                                Buffers: shared hit=19452, temp read=6847 written=6847"
"                                ->  Limit  (cost=283322.43..283323.61 rows=473 width=14) (actual time=5334.213..5334.288 rows=914 loops=1)"
"                                      Buffers: shared hit=19452, temp read=6847 written=6847"
"                                      ->  Sort  (cost=283322.43..283323.61 rows=473 width=14) (actual time=5334.210..5334.235 rows=914 loops=1)"
"                                            Sort Key: (count(DISTINCT fact.ticket_id)) DESC"
"                                            Sort Method: quicksort  Memory: 67kB"
"                                            Buffers: shared hit=19452, temp read=6847 written=6847"
"                                            ->  GroupAggregate  (cost=268296.69..283301.42 rows=473 width=14) (actual time=2768.464..5333.807 rows=914 loops=1)"
"                                                  Group Key: fact.product_id"
"                                                  Buffers: shared hit=19449, temp read=6847 written=6847"
"                                                  ->  Sort  (cost=268296.69..273296.69 rows=2000000 width=14) (actual time=2756.509..3782.823 rows=2000000 loops=1)"
"                                                        Sort Key: fact.product_id"
"                                                        Sort Method: external merge  Disk: 48080kB"
"                                                        Buffers: shared hit=19449, temp read=6014 written=6014"
"                                                        ->  Seq Scan on fact  (cost=0.00..39449.00 rows=2000000 width=14) (actual time=0.003..321.660 rows=2000000 loops=1)"
"                                                              Buffers: shared hit=19449"
"Planning time: 5.449 ms"
"Execution time: 12673.017 ms"

我可以根据查询计划进一步优化吗？

使用聚合优化PostgreSQL查询，对大型数据集进行分组

更新：

0 个答案: