PostgreSQL 9.2 - Agg計數查詢速度慢（distinct x）

我們正處於從MySQL到PG 9.2的轉換過程中。然而，我們在PG中遇到了我們的聚合查詢的障礙。他們需要花更長時間才能在PG和MySQL中運行。我認爲造成最大問題的是我們在總計查詢中計數（獨立x）。這會造成額外的排序，無論我們將WORK_MEM設置爲何種方式都會溢出到磁盤上。我們也嘗試將enable_sort設置爲「off」並將enable_seqscan設置爲「off」。另外，我們經常運行VACUUM ANALYZE。最後，我們無法利用索引，因爲我們的查詢有許多暗淡的字段，並且大部分都是連接的。這些桌子是40毫米到80毫米。請任何建議將有所幫助！這裏是一個解釋分析的例子。
PostgreSQL 9.2 - Agg計數查詢速度慢（distinct x）

查詢

SELECT 
    concat(
     cast(coalesce(trim(tablea.state_id),'na') as varchar), 
     '-', 
     cast(
      coalesce(
       CASE WHEN char_length(cast(tablea.case_num as varchar)) = 12 
        THEN left(cast(tablea.case_num as varchar), 2) 
        else left(cast(tablea.case_num as varchar), 1) 
       END,'na' 
      ) as varchar 
     ) 
    ), 
    to_char(tablea.visit_date,'yyyy-mm-01') , 
    coalesce(tablea.payor_code,0) , 
    coalesce(tablea.los,'other') , 
    case when cpt_group is null or cpt_group = '' 
     then '0' 
     else split_part(tablea.cpt_group,'-',1) 
    end , 
    case when cpt_group is null or cpt_group = '' 
     then '0' 
     else split_part(tablea.cpt_group,'-',2) 
    end , 
    case when (tablea.erp_code) isnull 
     then 'na' 
     else concat(
      cast(coalesce(trim(tablea.state_id), 'na') as varchar), 
      '-', 
      coalesce(cast(tablea.erp_code as varchar), 'na') , 
      '-', 
      coalesce(cast(tablea.mlp_code as varchar), 'na') 
      ) 
    end , 
    coalesce(tablea.erp_attnd,'n') , 
    count(distinct concat(tablea.state_id,tablea.case_num)) , 
    count(unique_rec_id), 
    sum(tablea.units) , 
    sum(tablea.total_amt) , 
    sum(tablea.total_rvu) , 
    sum(tablea.budget_rvu), 
    sum(tablea.work_rvu) , 
    sum(tablea.payroll_rvu) , 
    sum(extract(day from charges.insert_ts - charges.visit_date)) 
FROM tablea 
GROUP BY 1,2,3,4,5,6 ,7 ,8

表結構

state_id character varying(8), 
unique_rec_id bigint NOT NULL, 
case_num bigint, 
seq_nbr smallint, 
charge_code character varying(18), 
cpt_type character varying(2), 
cpt_code character varying(19), 
cpt_version_code character varying(2), 
erp_code integer, 
mlp_code integer, 
shared_svcs character varying(1), 
visit_date date, 
units numeric(6,2), 
unit_amt numeric(7,2), 
total_amt numeric(7,2), 
unit_rvu numeric(6,2), 
total_rvu numeric(6,2), 
place_of_serv smallint, 
insert_ts timestamp(6) without time zone, 
update_ts timestamp(6) without time zone, 
alw_amt numeric(8,2), 
pmt_amt numeric(8,2), 
adj_amt numeric(8,2), 
payor_code smallint, 
coder_id smallint, 
erp_attnd character varying(1), 
tos smallint, 
etos smallint, 
los character varying(5), 
budget_rvu numeric(6,2), 
work_rvu numeric(6,2), 
payroll_rvu numeric(6,2), 
cpt_group character varying(7), 
CONSTRAINT charges_pkey PRIMARY KEY (unique_rec_id)

Explain輸出

"GroupAggregate (cost=10007828904.29..10010019592.38 rows=3519178 width=77) (actual time=1270982.096..1448667.608 rows=7848213 loops=1)" 
" Output: (pg_catalog.concat((COALESCE(btrim((state_id)::text), 'na'::text))::character varying, '-', (COALESCE(CASE WHEN (char_length(((case_num)::character varying)::text) = 12) THEN "left"(((case_num)::character varying)::text, 2) ELSE "left"(((case_num)::character varying)::text, 1) END, 'na'::text))::character varying)), (to_char((visit_date)::timestamp with time zone, 'yyyy-mm-01'::text)), (COALESCE((payor_code)::integer, 0)), (COALESCE(los, 'other'::character varying)), (CASE WHEN ((cpt_group IS NULL) OR ((cpt_group)::text = ''::text)) THEN '0'::text ELSE split_part((cpt_group)::text, '-'::text, 1) END), (CASE WHEN ((cpt_group IS NULL) OR ((cpt_group)::text = ''::text)) THEN '0'::text ELSE split_part((cpt_group)::text, '-'::text, 2) END), (CASE WHEN (erp_code IS NULL) THEN 'na'::text ELSE pg_catalog.concat((COALESCE(btrim((state_id)::text), 'na'::text))::character varying, '-', COALESCE((erp_code)::character varying, 'na'::character varying), '-', COALESCE((mlp_code)::character varying, 'na'::character varying)) END), (COALESCE(erp_attnd, 'n'::character varying)), count(DISTINCT pg_catalog.concat(state_id, case_num)), count(unique_rec_id), sum(units), sum(total_amt), sum(total_rvu), sum(budget_rvu), sum(work_rvu), sum(payroll_rvu), sum(date_part('day'::text, (insert_ts - (visit_date)::timestamp without time zone)))" 
" Buffers: shared hit=866434, temp read=558843 written=558843" 
" -> Sort (cost=10007828904.29..10007916883.73 rows=35191776 width=77) (actual time=1270982.019..1314712.552 rows=36729163 loops=1)" 
"  Output: (pg_catalog.concat((COALESCE(btrim((state_id)::text), 'na'::text))::character varying, '-', (COALESCE(CASE WHEN (char_length(((case_num)::character varying)::text) = 12) THEN "left"(((case_num)::character varying)::text, 2) ELSE "left"(((case_num)::character varying)::text, 1) END, 'na'::text))::character varying)), (to_char((visit_date)::timestamp with time zone, 'yyyy-mm-01'::text)), (COALESCE((payor_code)::integer, 0)), (COALESCE(los, 'other'::character varying)), (CASE WHEN ((cpt_group IS NULL) OR ((cpt_group)::text = ''::text)) THEN '0'::text ELSE split_part((cpt_group)::text, '-'::text, 1) END), (CASE WHEN ((cpt_group IS NULL) OR ((cpt_group)::text = ''::text)) THEN '0'::text ELSE split_part((cpt_group)::text, '-'::text, 2) END), (CASE WHEN (erp_code IS NULL) THEN 'na'::text ELSE pg_catalog.concat((COALESCE(btrim((state_id)::text), 'na'::text))::character varying, '-', COALESCE((erp_code)::character varying, 'na'::character varying), '-', COALESCE((mlp_code)::character varying, 'na'::character varying)) END), (COALESCE(erp_attnd, 'n'::character varying)), state_id, case_num, unique_rec_id, units, total_amt, total_rvu, budget_rvu, work_rvu, payroll_rvu, insert_ts, visit_date" 
"  Sort Key: (pg_catalog.concat((COALESCE(btrim((charges.state_id)::text), 'na'::text))::character varying, '-', (COALESCE(CASE WHEN (char_length(((charges.case_num)::character varying)::text) = 12) THEN "left"(((charges.case_num)::character varying)::text, 2) ELSE "left"(((charges.case_num)::character varying)::text, 1) END, 'na'::text))::character varying)), (to_char((charges.visit_date)::timestamp with time zone, 'yyyy-mm-01'::text)), (COALESCE((charges.payor_code)::integer, 0)), (COALESCE(charges.los, 'other'::character varying)), (CASE WHEN ((charges.cpt_group IS NULL) OR ((charges.cpt_group)::text = ''::text)) THEN '0'::text ELSE split_part((charges.cpt_group)::text, '-'::text, 1) END), (CASE WHEN ((charges.cpt_group IS NULL) OR ((charges.cpt_group)::text = ''::text)) THEN '0'::text ELSE split_part((charges.cpt_group)::text, '-'::text, 2) END), (CASE WHEN (charges.erp_code IS NULL) THEN 'na'::text ELSE pg_catalog.concat((COALESCE(btrim((charges.state_id)::text), 'na'::text))::character varying, '-', COALESCE((charges.erp_code)::character varying, 'na'::character varying), '-', COALESCE((charges.mlp_code)::character varying, 'na'::character varying)) END), (COALESCE(charges.erp_attnd, 'n'::character varying))" 
"  Sort Method: external merge Disk: 4470728kB" 
"  Buffers: shared hit=866434, temp read=558843 written=558843" 
"  -> Seq Scan on public.charges (cost=10000000000.00..10003417837.76 rows=35191776 width=77) (actual time=0.062..182871.790 rows=36729163 loops=1)" 
"    Output: pg_catalog.concat((COALESCE(btrim((state_id)::text), 'na'::text))::character varying, '-', (COALESCE(CASE WHEN (char_length(((case_num)::character varying)::text) = 12) THEN "left"(((case_num)::character varying)::text, 2) ELSE "left"(((case_num)::character varying)::text, 1) END, 'na'::text))::character varying), to_char((visit_date)::timestamp with time zone, 'yyyy-mm-01'::text), COALESCE((payor_code)::integer, 0), COALESCE(los, 'other'::character varying), CASE WHEN ((cpt_group IS NULL) OR ((cpt_group)::text = ''::text)) THEN '0'::text ELSE split_part((cpt_group)::text, '-'::text, 1) END, CASE WHEN ((cpt_group IS NULL) OR ((cpt_group)::text = ''::text)) THEN '0'::text ELSE split_part((cpt_group)::text, '-'::text, 2) END, CASE WHEN (erp_code IS NULL) THEN 'na'::text ELSE pg_catalog.concat((COALESCE(btrim((state_id)::text), 'na'::text))::character varying, '-', COALESCE((erp_code)::character varying, 'na'::character varying), '-', COALESCE((mlp_code)::character varying, 'na'::character varying)) END, COALESCE(erp_attnd, 'n'::character varying), state_id, case_num, unique_rec_id, units, total_amt, total_rvu, budget_rvu, work_rvu, payroll_rvu, insert_ts, visit_date" 
"    Buffers: shared hit=866434" 
"Total runtime: 1450131.131 ms"

來源

2013-03-14 Tara

發佈原始查詢和表結構（'=> \ d my_table'） – 2013-03-14 14:04:55

我做膚淺的優化：

SELECT 
    concat(coalesce(state_id, 'na'), '-', case_num), 
    visit_date, 
    coalesce(payor_code, 0), 
    coalesce(los, 'other'), 
    case when cpt_group_1 is null or cpt_group = '' 
     then '0' 
     else cpt_group_1 
    end, 
    case when cpt_group_2 is null or cpt_group = '' 
     then '0' 
     else cpt_group_2 
    end, 
    erp_code , 
    coalesce(erp_attnd, 'n'), 
    count_case_num, 
    rec_id, 
    units, 
    total_amt, 
    total_rvu, 
    budget_rvu, 
    work_rvu, 
    payroll_rvu, 
    days 
from (
    select 
     tablea.state_id, 
     CASE WHEN tablea.case_num between 100000000000 and 999999999999 
      THEN left(cast(tablea.case_num as text), 2) 
      else left(cast(tablea.case_num as text), 1) 
     END case_num, 
     date_trunc('month', tablea.visit_date) visit_date, 
     tablea.payor_code, 
     tablea.los, 
     split_part(tablea.cpt_group, '-', 1) cpt_group_1, 
     split_part(tablea.cpt_group, '-', 2) cpt_group_2, 
     case when tablea.erp_code is null 
      then 'na' 
      else concat(
       coalesce(tablea.state_id, 'na'), 
       '-', 
       coalesce(cast(tablea.erp_code as text), 'na'), 
       '-', 
       coalesce(cast(tablea.mlp_code as text), 'na') 
       ) 
     end erp_code, 
     tablea.erp_attnd, 
     count(distinct (tablea.state_id, tablea.case_num)) count_case_num, 
     count(unique_rec_id) rec_id, 
     sum(tablea.units) units, 
     sum(tablea.total_amt) total_amt, 
     sum(tablea.total_rvu) total_rvu, 
     sum(tablea.budget_rvu) budget_rvu, 
     sum(tablea.work_rvu) work_rvu, 
     sum(tablea.payroll_rvu) payroll_rvu, 
     sum(extract(day from charges.insert_ts - charges.visit_date)) days 
    FROM tablea 
    GROUP BY 1, 2, 3, 4, 5, 6 ,7 ,8, 9 
) s

你擔心我的一部分從：更改

count(distinct concat(tablea.state_id,tablea.case_num))

到：

count(distinct (tablea.state_id, tablea.case_num))

來源

2013-03-14 15:35:10

謝謝您的回覆，但我已經試過了，並沒有對解釋計劃或執行時間進行更改:(。 – Tara 2013-03-14 15:54:02

@Tara更新了。我將難點優化到一個外部查詢希望有所作爲。 – 2013-03-14 16:06:06

我會試一試。謝謝 – Tara 2013-03-14 17:14:46

嘗試查詢前添加設置enable_sort='off';。

來源

2014-02-26 14:27:05 Ati

PostgreSQL 9.2 - Agg計數查詢速度慢（distinct x）

回答

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