Performance PostgreSQL查询未执行或花费太多时间_Performance_Postgresql

Performance PostgreSQL查询未执行或花费太多时间

performance postgresql

Performance PostgreSQL查询未执行或花费太多时间,performance,postgresql,Performance,Postgresql,执行查询时，我正在windows上使用PostgreSQL 9.2： PostgreSQL服务器端config 最大连接数10000个最大堆栈深度2MB 共享缓冲区1GB 温度缓冲区1GB 我是新来的，因此非常感谢您的任何建议，您将看到您的查询速度缓慢的地方但在进行查询优化之前，请阅读相关教程，了解什么是seqscan/loop/cast等。。。请尝试重写您的查询以使其更简单！我想你可以请阅读@wildplasser所说的内容，因为Select coalesce（PBillDate，n

执行查询时，我正在windows上使用PostgreSQL 9.2：

```
PostgreSQL
```
服务器端
```
config
```

最大连接数10000个
最大堆栈深度2MB
共享缓冲区1GB
温度缓冲区1GB

我是新来的，因此非常感谢您的任何建议，您将看到您的查询速度缓慢的地方

但在进行查询优化之前，请阅读相关教程，了解什么是seqscan/loop/cast等。。。请尝试重写您的查询以使其更简单！我想你可以

请阅读@wildplasser所说的内容，因为

Select coalesce（PBillDate，null）from

是由于对coalesce的使用不全面…

Select PBillDate from

是相同的，因此不必进行必要的处理

但为了帮助您，在这种情况下，我尝试删除所有select子句以仅保留一个，并删除select子句和播放查询不需要的join。尝试使用正确的联接逐个重新添加select子句，如果您发现查询时间在增长，请进行解释，转到depesz网站阅读解释，并尝试检测您的查询速度慢的地方，然后添加索引或重写它

阅读一个大的查询并尝试优化它是非常困难的，所以一步一步地添加select子句，您就会找到解决方案

并检查您的统计数据是否正确，如果不正确，您的解释将不正确。您可以使用真空刷新统计数据，并尝试使用

explain analyze

而不是

explain

，因为

explain analyze

执行真正的查询，并返回许多其他信息以查看每个部件的成本

阅读有关解释分析的教程，因为您有许多非常有用的选项；）

致以最诚挚的问候

这个查询很难辨认。非常感谢您将其包括在内并

解释分析。看起来您的行数估计值很好。90%的时间都花在节点19上的seqscan上。@CraigRinger，正如我说的，我是新手，下一步该怎么做？这个系统上的存储是什么？出于测试目的，请仅尝试使用SET random\u page\u cost=1.1
重新耳轴查询。还可以尝试设置enable_nestloop=off
并显示结果计划。off-topic:。。。从…中选择合并（PBillDate，null）
是疯狂的结果，IMHO.Select
列表中的所有标量子查询（使用limit 1）在我看来有些可疑。如果真的需要它们，这可能表明数据模型中存在问题。无论如何，感谢这些信息，我已经找出了问题的主要原因，即该查询中的3个表没有索引。最后，我找到了它，并为它们分配了正确的索引。现在，我的查询运行良好，我需要再次根据您的答案对其进行优化
SELECT
    gtab16.VrId,
    coalesce((
        select (gtab09.TdAmt+gtab09.CdAmt)
        from gtab09
        Where gtab09.JrmId = gtab16.JrmId
        limit 1
        ), 0::money
    ) as DisAmount,
    gtab02.VrName,
    gtab02.Vrlongname,
    gtab16.AcYrId,
    CASE WHEN gtab16.vrid = 28 THEN gtab16.RefNo ELSE gtab16.VrNo END AS VrNo,
    gtab16.RefNo,
    CASE
        WHEN gtab16.VrId = 10 THEN cast((
            Select coalesce(PBillDate,null)
            from gtab09
            Where gtab09.JrmId = gtab16.JrmId
        ) as bpchar)
        ELSE ''
    END As BillDate ,
    Cast(gtab16.VrDate As timestamp) As VrDate,
    gtab16.AgeDate,
    (
        SELECT coalesce(Sum(gtab18.ageamt),0::money)
        FROM
            (gtab16 AS A INNER JOIN gtab17 AS B ON A.jrmId = B.JrmId)
            INNER JOIN
            gtab18 ON B.JrDetId = gtab18.crjrdetid
        WHERE gtab18.drjrdetid = Gtab17.JrDetId AND A.AgeDate <= '2014-07-09'
    ) AS AgedAmt,
    case when gtab17.dr > 0::money then gtab17.Dr else gtab17.Cr end  AS VrAmt,
    gtab17.AcId, gtab12.AcName,
    gtab12.AcShortName,
    gtab12.PhoneOff,
    case when gtab17.cr > 0::money then 1 else 0 end AS Receipt,
    gtab47.AreaName,
    gtab16.JrMId,
    gtab17.JrDetId,
    date_part('day','2014-07-09' - Gtab16.agedate) as DayCount,
    (
        SELECT coalesce(sum(chqAmt),0::money)
        From gtab19
        Where PartyAcId = gtab17.acid and vrid = 19 And Pdc =1
    ) as PDCCheq,
    30 As Span1,
    60 As Span2,
    90 As Span3
FROM
    (
        gtab16
        INNER JOIN
        (
            gtab17
            INNER JOIN
            gtab12 ON gtab17.AcId = gtab12.acid
        ) ON gtab16.jrmId = gtab17.JrmId
    )
    INNER JOIN gtab02 ON gtab16.VrId = gtab02.vrId
    INNER JOIN gtab47 ON gtab12.AreaId = gtab47.AreaId
WHERE
    gtab16.BranchID = 1 And
    gtab17.Dr > 0::money AND
    case when gtab16.AcYrid = 2 then 1 else gtab16.VrId  end <> 6 And
    date_part('day','2014-07-09' - Gtab16.agedate)  >= 0 AND
    (gtab12.AcGrCode = '204' or gtab12.AcGrCode = '103') And
    gtab47.AreaId IN (7) AND
    date_part('day',  '2014-07-09' - gtab16.AgeDate) >= 0 And
    (gtab17.Dr - (
        SELECT coalesce(Sum(gtab18.ageamt),0::money)
        From
            (
                gtab16 AS A
                INNER JOIN gtab17 AS B ON A.jrmId = B.JrmId
            )
            INNER JOIN gtab18 ON B.JrDetId = gtab18.crjrdetid
        Where
            gtab18.drjrdetid = Gtab17.JrDetId AND
            A.AgeDate <= '2014-07-09') > 0::money
    ) AND
    gtab16.VrDate Between '2014-07-01' And '2014-07-09'

"Nested Loop  (cost=0.00..98913858.59 rows=9 width=363) (actual time=302403.378..302628.382 rows=71 loops=1)"
"  ->  Seq Scan on gtab47  (cost=0.00..1.30 rows=1 width=122) (actual time=0.006..0.010 rows=1 loops=1)"
"        Filter: (areaid = 7)"
"        Rows Removed by Filter: 23"
"  ->  Nested Loop  (cost=0.00..98908508.69 rows=9 width=249) (actual time=302400.148..302405.795 rows=71 loops=1)"
"        Join Filter: (gtab16.vrid = gtab02.vrid)"
"        Rows Removed by Join Filter: 3834"
"        ->  Seq Scan on gtab02  (cost=0.00..1.55 rows=55 width=150) (actual time=0.004..0.052 rows=55 loops=1)"
"        ->  Materialize  (cost=0.00..98908499.74 rows=9 width=103) (actual time=5380.762..5498.218 rows=71 loops=55)"
"              ->  Nested Loop  (cost=0.00..98908499.70 rows=9 width=103) (actual time=295941.855..302398.524 rows=71 loops=1)"
"                    Join Filter: (gtab17.jrmid = gtab16.jrmid)"
"                    Rows Removed by Join Filter: 1886191"
"                    ->  Nested Loop  (cost=0.00..98897543.98 rows=2015 width=69) (actual time=7.437..299102.826 rows=2037 loops=1)"
"                          Join Filter: (gtab17.acid = gtab12.acid)"
"                          Rows Removed by Join Filter: 12893055"
"                          ->  Seq Scan on gtab17  (cost=0.00..98819605.03 rows=29138 width=28) (actual time=2.974..276230.715 rows=68228 loops=1)"
"                                Filter: ((dr > (0)::money) AND ((dr - (SubPlan 5)) > (0)::money))"
"                                Rows Removed by Filter: 111761"
"                                SubPlan 5"
"                                  ->  Aggregate  (cost=548.98..549.00 rows=1 width=8) (actual time=3.131..3.132 rows=1 loops=88001)"
"                                        ->  Nested Loop  (cost=0.71..548.98 rows=1 width=8) (actual time=2.707..3.126 rows=0 loops=88001)"
"                                              ->  Nested Loop  (cost=0.42..548.64 rows=1 width=12) (actual time=2.701..3.119 rows=0 loops=88001)"
"                                                    ->  Seq Scan on gtab18 gtab18_1  (cost=0.00..540.19 rows=1 width=12) (actual time=2.693..3.109 rows=0 loops=88001)"
"                                                          Filter: (drjrdetid = gtab17.jrdetid)"
"                                                          Rows Removed by Filter: 28575"
"                                                    ->  Index Scan using gtab17_pkey on gtab17 b_1  (cost=0.42..8.44 rows=1 width=8) (actual time=0.005..0.006 rows=1 loops=28574)"
"                                                          Index Cond: (jrdetid = gtab18_1.crjrdetid)"
"                                              ->  Index Scan using gtab16_pkey on gtab16 a_1  (cost=0.29..0.33 rows=1 width=4) (actual time=0.004..0.005 rows=1 loops=28574)"
"                                                    Index Cond: (jrmid = b_1.jrmid)"
"                                                    Filter: (agedate <= '2014-07-09 00:00:00'::timestamp without time zone)"
"                          ->  Materialize  (cost=0.00..140.94 rows=178 width=45) (actual time=0.001..0.160 rows=189 loops=68228)"
"                                ->  Seq Scan on gtab12  (cost=0.00..140.05 rows=178 width=45) (actual time=0.057..0.927 rows=189 loops=1)"
"                                      Filter: ((areaid = 7) AND (((acgrcode)::text = '204'::text) OR ((acgrcode)::text = '103'::text)))"
"                                      Rows Removed by Filter: 2385"
"                    ->  Materialize  (cost=0.00..3037.42 rows=262 width=38) (actual time=0.006..0.788 rows=926 loops=2037)"
"                          ->  Seq Scan on gtab16  (cost=0.00..3036.11 rows=262 width=38) (actual time=10.342..13.037 rows=926 loops=1)"
"                                Filter: ((vrdate >= '2014-07-01 00:00:00'::timestamp without time zone) AND (vrdate <= '2014-07-09 00:00:00'::timestamp without time zone) AND (branchid = 1) AND (CASE WHEN (acyrid = 2) THEN 1 ELSE vrid END <> 6) AND (date_p (...)"
"                                Rows Removed by Filter: 58837"
"  SubPlan 1"
"    ->  Limit  (cost=0.29..8.31 rows=1 width=16) (actual time=0.011..0.012 rows=1 loops=71)"
"          ->  Index Scan using gtab09_jrmid_idx on gtab09  (cost=0.29..8.31 rows=1 width=16) (actual time=0.007..0.007 rows=1 loops=71)"
"                Index Cond: (jrmid = gtab16.jrmid)"
"  SubPlan 2"
"    ->  Index Scan using gtab09_jrmid_idx on gtab09 gtab09_1  (cost=0.29..8.31 rows=1 width=8) (never executed)"
"          Index Cond: (jrmid = gtab16.jrmid)"
"  SubPlan 3"
"    ->  Aggregate  (cost=548.98..549.00 rows=1 width=8) (actual time=2.975..2.975 rows=1 loops=71)"
"          ->  Nested Loop  (cost=0.71..548.98 rows=1 width=8) (actual time=2.968..2.970 rows=0 loops=71)"
"                ->  Nested Loop  (cost=0.42..548.64 rows=1 width=12) (actual time=2.965..2.966 rows=0 loops=71)"
"                      ->  Seq Scan on gtab18  (cost=0.00..540.19 rows=1 width=12) (actual time=2.959..2.960 rows=0 loops=71)"
"                            Filter: (drjrdetid = gtab17.jrdetid)"
"                            Rows Removed by Filter: 28575"
"                      ->  Index Scan using gtab17_pkey on gtab17 b  (cost=0.42..8.44 rows=1 width=8) (actual time=0.005..0.006 rows=1 loops=1)"
"                            Index Cond: (jrdetid = gtab18.crjrdetid)"
"                ->  Index Scan using gtab16_pkey on gtab16 a  (cost=0.29..0.33 rows=1 width=4) (actual time=0.007..0.009 rows=1 loops=1)"
"                      Index Cond: (jrmid = b.jrmid)"
"                      Filter: (agedate <= '2014-07-09 00:00:00'::timestamp without time zone)"
"  SubPlan 4"
"    ->  Aggregate  (cost=28.63..28.64 rows=1 width=8) (actual time=0.130..0.131 rows=1 loops=71)"
"          ->  Seq Scan on gtab19  (cost=0.00..28.62 rows=1 width=8) (actual time=0.124..0.124 rows=0 loops=71)"
"                Filter: ((partyacid = gtab17.acid) AND (vrid = 19) AND (pdc = 1))"
"                Rows Removed by Filter: 607"
"Total runtime: 302628.704 ms"