Re: [GENERAL] Queries are taking way longer in 9.6 than 9.5

On Tue, Jan 17, 2017 at 2:31 PM, Ravi Tammineni <
rtammineni(at)partner(dot)aligntech(dot)com> wrote:

> Hi,
>
>
>
> We have recently upgraded to 9.6 and few queries are performing very
> poorly. Query execution time has increased more 4 or 5 times in 9.6. Qeruy
> execution plan is also completely changed. I am not sure whether its
> because of Parallel feature or any bug in 9.6. There are few similar kind
> of queries and all of them are taking more time in 9.6.
>
>
>
> Following query is taking 70ms in 9.5 and the same query is taking 2
> minutes in 9.6. Execution plan is totally different in 9.6 and seems like
> there is a major flaw while generating the execution plan. Instead of
> filtering the low cardinality, its filtering from biggest table. Somehow
> nested loop joins are screwed up.
>
>
>
>
>
> I really appreciate your help.
>
>
>
> explain analyze
>
> SELECT count(*)
>
> FROM
>
> tblCnPatientOrderMap po
>
> JOIN tblPuOrderStatus os ON po.vip_order_id = os.vip_order_id
>
> JOIN tblPuOrderStatusHistory osh ON os.order_status_history_id =
> osh.order_status_history_id
>
> WHERE
>
> exists(SELECT 1
>
> FROM
>
> tblCnDoctorPatientMap d
>
> WHERE d.vip_patient_id = po.vip_patient_id
>
> AND exists(SELECT 1
>
> FROM
>
> tblCnAccounts a
>
> WHERE a.master_user_id = d.master_user_id AND
>
> a.user_name = 'dddddd'))
>
> AND osh.vip_order_type IN (17)--assist
>
> --AND osh.tx_submit_date IS NOT NULL
>
> AND osh.cancelled_date IS NULL
>
> AND osh.cc_accept_date IS NOT NULL;
>
>
>
>
>
> ########################## 9.5 Execution plan
>
>
>
>
> QUERY PLAN
>
> ------------------------------------------------------------
> ------------------------------------------------------------
> -----------------------------
>
> Aggregate (cost=1177.25..1177.26 rows=1 width=0)
>
> -> Nested Loop (cost=67.83..1177.25 rows=5 width=0)
>
> -> Nested Loop (cost=67.71..254.81 rows=1322 width=4)
>
> -> Nested Loop (cost=67.63..104.45 rows=1322 width=4)
>
> -> HashAggregate (cost=67.54..68.12 rows=192
> width=4)
>
> Group Key: d.vip_patient_id
>
>
>
> -> Nested Loop (cost=0.17..67.44 rows=192
> width=4)
>
> -> Index Scan using unq_user_name on
> tblcnaccounts a (cost=0.08..4.09 rows=1 width=4)
>
> Index Cond: ((user_name)::text =
> 'dddddd'::text)
>
>
>
> -> Index Only Scan using
> idx_tblcndoctorpatientmap on tblcndoctorpatientmap d (cost=0.09..62.78
> rows=192 width=8)
>
> Index Cond: (master_user_id =
> a.master_user_id)
>
> -> Index Scan using idx_tblcnpatientordermap on
> tblcnpatientordermap po (cost=0.09..0.17 rows=7 width=8)
>
> Index Cond: (vip_patient_id = d.vip_patient_id)
>
> -> Index Scan using tblpuorderstatus_pkey on
> tblpuorderstatus os (cost=0.09..0.11 rows=1 width=8)
>
> Index Cond: (vip_order_id = po.vip_order_id)
>
> -> Index Scan using tblpuorderstatushistory_pkey on
> tblpuorderstatushistory osh (cost=0.11..0.69 rows=1 width=4)
>
> Index Cond: (order_status_history_id =
> os.order_status_history_id)
>
> Filter: ((cancelled_date IS NULL) AND (cc_accept_date IS
> NOT NULL) AND (vip_order_type = 17))
>
>
>
> ############################################################
> #########################################################################
>
>
>
> ########################## 9.6 Execution plan
>
> QUERY PLAN
>
> ------------------------------------------------------------
> -------------------------------------------------------------------------
>
> Aggregate (cost=3185034.17..3185034.17 rows=1 width=8)
>
> -> Nested Loop Semi Join (cost=3012833.92..3185010.91 rows=46511
> width=0)
>
>
>
> -> Nested Loop (cost=3012833.75..3137291.51 rows=46511 width=4)
>
>
>
> -> Hash Join (cost=3012833.67..3117860.77 rows=46511
> width=4)
>
> Hash Cond: (os.order_status_history_id =
> osh.order_status_history_id)
>
>
>
> -> Seq Scan on tblpuorderstatus os
> (cost=0.00..96498.46 rows=11185486 width=8)
>
> -> Hash (cost=3010979.77..3010979.77 rows=529686
> width=4)
>
> -> Gather (cost=1000.00..3010979.77
> rows=529686 width=4)
>
> Workers Planned: 2
>
> -> Parallel Seq Scan on
> tblpuorderstatushistory osh (cost=0.00..2957011.17 rows=220702 width=4)
>
>
>
> Filter: ((cancelled_date IS NULL)
> AND (cc_accept_date IS NOT NULL) AND (vip_order_type = 17))
>
>
>
> -> Index Scan using tblcnpatientordermap_pkey on
> tblcnpatientordermap po (cost=0.09..0.41 rows=1 width=8)
>
>
>
> Index Cond: (vip_order_id = os.vip_order_id)
>
>
>
> -> Nested Loop Semi Join (cost=0.17..1.02 rows=1 width=4)
>
> -> Index Scan using tblcndoctorpatientmap_pkey on
> tblcndoctorpatientmap d (cost=0.09..0.39 rows=1 width=8)
>
> Index Cond: (vip_patient_id = po.vip_patient_id)
>
> -> Index Scan using tblcnaccounts_pkey on tblcnaccounts a
> (cost=0.08..0.36 rows=1 width=4)
>
> Index Cond: (master_user_id = d.master_user_id)
>
> Filter: ((user_name)::text = 'dddddd'::text)
>
> (19 rows)
>
>
>
>
>
> Regards,
>
> ravi
>

1. Have you run ANALYZE on the database after upgrading?
2. Have you insured that the proper changed were done to the
postgresql.conf in 9.6?

--
*Melvin Davidson*
I reserve the right to fantasize. Whether or not you
wish to share my fantasy is entirely up to you.