Re: Bad plan

In my opinion this is the Achilles heel of the postgres optimizer. Row
estimates should never return 1, unless the estimate is provably <=1. This
is particularly a problem with join estimates. A dumb fix for this is to
change clamp_join_row_est() to never return a value <2. This fixes most of
my observed poor plans. The real fix is to track uniqueness (or provable
max rows) along with the selectivity estimate.

Here's the dumb fix.

https://github.com/labkey-matthewb/postgres/commit/b1fd99f4deffbbf3db2172ccaba51a34f18d1b1a

On Tue, Jan 23, 2018 at 7:59 AM, Laurent Martelli <martellilaurent(at)gmail(dot)com
> wrote:

> I've have a look to the plan with pgadmin, and I think the problem is
> rather here :
>
> -> Sort (cost=4997.11..4997.11 rows=1 width=69) (actual
> time=27.427..28.896 rows=7359 loops=1)
> Sort Key: amendment.id
> Sort Method: quicksort Memory: 1227kB
> -> Nested Loop (cost=183.44..4997.10 rows=1 width=69) (actual
> time=1.115..24.616 rows=7359 loops=1)
> -> Nested Loop (cost=183.15..4996.59 rows=1 width=49)
> (actual time=1.107..9.091 rows=7360 loops=1)
> -> Index Scan using uk_3b1y5vw9gmh7u3jj8aa2uy0b9 on
> contact_partner businessprovider (cost=0.42..8.44 rows=1 width=13)
> (actual time=0.010..0.010 rows=1 loops=1)
> Index Cond: ((business_provider_code)::text =
> 'BRZH'::text)
> -> Bitmap Heap Scan on contract_contract_line
> contractline (cost=182.73..4907.58 rows=8057 width=52) (actual
> time=1.086..5.231 rows=7360 loops=1)
> Recheck Cond: (business_provider_partner =
> businessprovider.id)
> Heap Blocks: exact=3586
> -> Bitmap Index Scan on
> contract_contract_line_business_provider_partner_idx
> (cost=0.00..180.72 rows=8057 width=0) (actual time=0.655..0.655
> rows=7360 loops=1)
> Index Cond: (business_provider_partner =
> businessprovider.id)
> -> Index Scan using contract_amendment_pkey on
> contract_amendment amendment (cost=0.29..0.50 rows=1 width=28)
> (actual time=0.001..0.002 rows=1 loops=7360)
> Index Cond: (id = contractline.amendment)
>
> The bitmap scan on contract_contract_line is good (8057 vs 7360 rows),
> and so is the index scan (1 row), but the JOIN with "contact_partner
> businessProvider" should give the 8057 rows from the bitmap scan,
> shouldn't it ?
>
>
> 2018-01-23 16:38 GMT+01:00 Laurent Martelli <martellilaurent(at)gmail(dot)com>:
> > 2018-01-23 16:18 GMT+01:00 Justin Pryzby <pryzby(at)telsasoft(dot)com>:
> >> On Tue, Jan 23, 2018 at 01:03:49PM +0100, Laurent Martelli wrote:
> >>
> >>> Here is the default plan :
> >>
> >> Can you resend without line breaks or paste a link to explain.depesz?
> >
> > I hope it's better like that. I've attached it too, just in case.
> >
> >>
> >> The problem appears to be here:
> >>
> >> -> Nested Loop Left Join (cost=32067.09..39197.85 rows=1 width=276)
> (actual time=342.725..340775.031 rows=7359 loops=1)
> >> Join Filter: (sh.share_holder_partner = partner.id)
> >> Rows Removed by Join Filter: 204915707
> >>
> >> Justin
> >
> >
> >
> > QUERY PLAN
> > ------------------------------------------------------------
> ------------------------------------------------------------
> ------------------------------------------------------------
> ------------------------------------------------------------
> ------------------------------------------------------------
> ------------------------------------------------------------------
> > Sort (cost=39200.76..39200.76 rows=1 width=1066) (actual
> > time=341273.300..341274.244 rows=7359 loops=1)
> > Sort Key: ((array_agg(subscribed_power.subscribed_power))[1]) DESC,
> > status.name, contractline.id
> > Sort Method: quicksort Memory: 3930kB
> > -> Nested Loop Left Join (cost=32069.19..39200.75 rows=1
> > width=1066) (actual time=342.806..341203.151 rows=7359 loops=1)
> > -> Nested Loop Left Join (cost=32069.05..39200.50 rows=1
> > width=508) (actual time=342.784..341102.848 rows=7359 loops=1)
> > -> Nested Loop Left Join (cost=32068.77..39200.20
> > rows=1 width=500) (actual time=342.778..341070.310 rows=7359 loops=1)
> > -> Nested Loop Left Join
> > (cost=32068.64..39200.04 rows=1 width=507) (actual
> > time=342.776..341058.256 rows=7359 loops=1)
> > Join Filter: (cca.address = adr_contact.id)
> > Rows Removed by Join Filter: 2254
> > -> Nested Loop Left Join
> > (cost=32068.22..39199.55 rows=1 width=515) (actual
> > time=342.767..340997.058 rows=7359 loops=1)
> > -> Nested Loop Left Join
> > (cost=32067.79..39198.84 rows=1 width=447) (actual
> > time=342.753..340932.286 rows=7359 loops=1)
> > -> Nested Loop Left Join
> > (cost=32067.65..39198.67 rows=1 width=421) (actual
> > time=342.748..340896.132 rows=7359 loops=1)
> > -> Nested Loop Left Join
> > (cost=32067.23..39198.01 rows=1 width=279) (actual
> > time=342.739..340821.987 rows=7359 loops=1)
> > -> Nested Loop
> > Left Join (cost=32067.09..39197.85 rows=1 width=276) (actual
> > time=342.725..340775.031 rows=7359 loops=1)
> > Join Filter:
> > (sh.share_holder_partner = partner.id)
> > Rows Removed
> > by Join Filter: 204915707
> > -> Nested
> > Loop Left Join (cost=28514.61..34092.46 rows=1 width=244) (actual
> > time=287.323..610.192 rows=7359 loops=1)
> > ->
> > Nested Loop Left Join (cost=28514.47..34092.30 rows=1 width=239)
> > (actual time=287.318..573.234 rows=7359 loops=1)
> >
> > -> Hash Right Join (cost=28513.48..34090.65 rows=1 width=159)
> > (actual time=287.293..379.564 rows=7359 loops=1)
> >
> > Hash Cond: (ws.contract_line = contractline.id)
> >
> > -> Seq Scan on shareholder_web_subscription ws
> > (cost=0.00..5378.84 rows=52884 width=24) (actual time=0.006..12.307
> > rows=52884 loops=1)
> >
> > -> Hash (cost=28513.47..28513.47 rows=1 width=143) (actual
> > time=287.243..287.243 rows=7359 loops=1)
> >
> > Buckets: 8192 (originally 1024) Batches: 1 (originally 1)
> > Memory Usage: 1173kB
> >
> > -> Nested Loop Left Join (cost=17456.16..28513.47 rows=1
> > width=143) (actual time=85.005..284.689 rows=7359 loops=1)
> >
> > -> Nested Loop (cost=17456.03..28513.31 rows=1
> > width=148) (actual time=85.000..276.599 rows=7359 loops=1)
> >
> > -> Nested Loop Left Join
> > (cost=17455.73..28512.84 rows=1 width=148) (actual
> > time=84.993..261.954 rows=7359 loops=1)
> >
> > -> Nested Loop (cost=17455.60..28512.67
> > rows=1 width=140) (actual time=84.989..253.715 rows=7359 loops=1)
> >
> > -> Nested Loop
> > (cost=17455.18..28511.93 rows=1 width=93) (actual time=84.981..230.977
> > rows=7359 loops=1)
> >
> > -> Merge Right Join
> > (cost=17454.89..28511.52 rows=1 width=93) (actual time=84.974..211.200
> > rows=7359 loops=1)
> >
> > Merge Cond:
> > (subscribed_power.amendment = amendment.id)
> >
> > -> GroupAggregate
> > (cost=12457.78..22574.03 rows=75229 width=168) (actual
> > time=57.500..175.674 rows=83432 loops=1)
> >
> > Group Key:
> > subscribed_power.amendment
> >
> > -> Merge Join
> > (cost=12457.78..20764.08 rows=173917 width=12) (actual
> > time=57.479..129.530 rows=87938 loops=1)
> >
> > Merge Cond:
> > (subscribed_power.amendment = amendment_1.id)
> >
> > -> Index
> > Scan using contract_subscribed_power_amendment_idx on
> > contract_subscribed_power subscribed_power (cost=0.42..13523.09
> > rows=173917 width=12) (actual time=0.009..33.704 rows=87963 loops=1)
> >
> > -> Sort
> > (cost=12457.36..12666.43 rows=83629 width=8) (actual
> > time=57.467..67.071 rows=88019 loops=1)
> >
> > Sort
> > Key: amendment_1.id
> >
> > Sort
> > Method: quicksort Memory: 6988kB
> >
> > ->
> > Hash Join (cost=10.21..5619.97 rows=83629 width=8) (actual
> > time=0.112..40.965 rows=83532 loops=1)
> >
> >
> > Hash Cond: (amendment_1.pricing = pricing.id)
> >
> >
> > -> Seq Scan on contract_amendment amendment_1 (cost=0.00..4460.29
> > rows=83629 width=16) (actual time=0.004..6.988 rows=83629 loops=1)
> >
> >
> > -> Hash (cost=8.43..8.43 rows=142 width=8) (actual time=0.095..0.095
> > rows=141 loops=1)
> >
> >
> > Buckets: 1024 Batches: 1 Memory Usage: 14kB
> >
> >
> > -> Hash Join (cost=1.07..8.43 rows=142 width=8) (actual
> > time=0.012..0.078 rows=141 loops=1)
> >
> >
> > Hash Cond: (pricing.elec_range = elec_range.id)
> >
> >
> > -> Seq Scan on pricing_pricing pricing (cost=0.00..5.42
> > rows=142 width=16) (actual time=0.003..0.015 rows=142 loops=1)
> >
> >
> > -> Hash (cost=1.03..1.03 rows=3 width=8) (actual
> > time=0.006..0.006 rows=3 loops=1)
> >
> >
> > Buckets: 1024 Batches: 1 Memory Usage: 9kB
> >
> >
> > -> Seq Scan on fluid_elec_range elec_range
> > (cost=0.00..1.03 rows=3 width=8) (actual time=0.003..0.005 rows=3
> > loops=1)
> >
> > -> Sort
> > (cost=4997.11..4997.11 rows=1 width=69) (actual time=27.427..28.896
> > rows=7359 loops=1)
> >
> > Sort Key:
> > amendment.id
> >
> > Sort Method:
> > quicksort Memory: 1227kB
> >
> > -> Nested Loop
> > (cost=183.44..4997.10 rows=1 width=69) (actual time=1.115..24.616
> > rows=7359 loops=1)
> >
> > -> Nested
> > Loop (cost=183.15..4996.59 rows=1 width=49) (actual time=1.107..9.091
> > rows=7360 loops=1)
> >
> > ->
> > Index Scan using uk_3b1y5vw9gmh7u3jj8aa2uy0b9 on contact_partner
> > businessprovider (cost=0.42..8.44 rows=1 width=13) (actual
> > time=0.010..0.010 rows=1 loops=1)
> >
> >
> > Index Cond: ((business_provider_code)::text = 'BRZH'::text)
> >
> > ->
> > Bitmap Heap Scan on contract_contract_line contractline
> > (cost=182.73..4907.58 rows=8057 width=52) (actual time=1.086..5.231
> > rows=7360 loops=1)
> >
> >
> > Recheck Cond: (business_provider_partner = businessprovider.id)
> >
> >
> > Heap Blocks: exact=3586
> >
> >
> > -> Bitmap Index Scan on
> > contract_contract_line_business_provider_partner_idx
> > (cost=0.00..180.72 rows=8057 width=0) (actual time=0.655..0.655
> > rows=7360 loops=1)
> >
> >
> > Index Cond: (business_provider_partner = businessprovider.id)
> >
> > -> Index
> > Scan using contract_amendment_pkey on contract_amendment amendment
> > (cost=0.29..0.50 rows=1 width=28) (actual time=0.001..0.002 rows=1
> > loops=7360)
> >
> > Index
> > Cond: (id = contractline.amendment)
> >
> > -> Index Scan using
> > contract_contract_pkey on contract_contract contract (cost=0.29..0.40
> > rows=1 width=24) (actual time=0.002..0.002 rows=1 loops=7359)
> >
> > Index Cond: (id =
> > contractline.contract)
> >
> > -> Index Scan using
> > contact_partner_pkey on contact_partner partner (cost=0.42..0.74
> > rows=1 width=55) (actual time=0.002..0.002 rows=1 loops=7359)
> >
> > Index Cond: (id =
> > contract.main_client_partner)
> >
> > -> Index Scan using
> > contact_client_nature_pkey on contact_client_nature clientnature
> > (cost=0.14..0.15 rows=1 width=24) (actual time=0.001..0.001 rows=1
> > loops=7359)
> >
> > Index Cond: (id =
> > partner.client_nature)
> >
> > -> Index Scan using territory_mpt_pkey on
> > territory_mpt mpt (cost=0.29..0.46 rows=1 width=16) (actual
> > time=0.001..0.001 rows=1 loops=7359)
> >
> > Index Cond: (id = contractline.mpt)
> >
> > -> Index Scan using contract_user_segment_pkey on
> > contract_user_segment usersegment (cost=0.14..0.15 rows=1 width=11)
> > (actual time=0.001..0.001 rows=1 loops=7359)
> >
> > Index Cond: (id = amendment.user_segment)
> >
> > -> Nested Loop Left Join (cost=0.99..1.64 rows=1 width=96) (actual
> > time=0.021..0.025 rows=1 loops=7359)
> >
> > -> Nested Loop Left Join (cost=0.85..1.35 rows=1 width=89)
> > (actual time=0.017..0.020 rows=1 loops=7359)
> >
> > -> Nested Loop Left Join (cost=0.71..1.18 rows=1 width=76)
> > (actual time=0.013..0.014 rows=1 loops=7359)
> >
> > -> Index Scan using contact_address_pkey on
> > contact_address a (cost=0.42..0.85 rows=1 width=84) (actual
> > time=0.005..0.006 rows=1 loops=7359)
> >
> > Index Cond: (mpt.address = id)
> >
> > -> Index Scan using territory_commune_pkey on
> > territory_commune commune (cost=0.29..0.32 rows=1 width=16) (actual
> > time=0.005..0.006 rows=1 loops=7359)
> >
> > Index Cond: (a.commune = id)
> >
> > -> Index Scan using territory_department_pkey on
> > territory_department dept (cost=0.14..0.16 rows=1 width=37) (actual
> > time=0.003..0.004 rows=1 loops=7359)
> >
> > Index Cond: (commune.department = id)
> >
> > -> Index Scan using territory_region_pkey on territory_region reg
> > (cost=0.14..0.27 rows=1 width=23) (actual time=0.003..0.003 rows=1
> > loops=7359)
> >
> > Index Cond: (dept.region = id)
> > ->
> > Index Scan using administration_status_pkey on administration_status
> > status (cost=0.14..0.16 rows=1 width=21) (actual time=0.003..0.003
> > rows=1 loops=7359)
> >
> > Index Cond: (id = contractline.status)
> > ->
> > GroupAggregate (cost=3552.48..4479.27 rows=27827 width=80) (actual
> > time=0.006..44.205 rows=27846 loops=7359)
> > Group
> > Key: sh.share_holder_partner
> > ->
> > Sort (cost=3552.48..3624.85 rows=28948 width=17) (actual
> > time=0.003..2.913 rows=28946 loops=7359)
> >
> > Sort Key: sh.share_holder_partner
> >
> > Sort Method: quicksort Memory: 3030kB
> >
> > -> Hash Join (cost=2.23..1407.26 rows=28948 width=17) (actual
> > time=0.024..12.296 rows=28946 loops=1)
> >
> > Hash Cond: (sh.company = sh_coop.id)
> >
> > -> Seq Scan on shareholder_share_holder sh (cost=0.00..1007.00
> > rows=28948 width=20) (actual time=0.007..5.495 rows=28946 loops=1)
> >
> > Filter: (nb_share > 0)
> >
> > Rows Removed by Filter: 1934
> >
> > -> Hash (cost=2.10..2.10 rows=10 width=13) (actual
> > time=0.009..0.009 rows=10 loops=1)
> >
> > Buckets: 1024 Batches: 1 Memory Usage: 9kB
> >
> > -> Seq Scan on contact_company sh_coop (cost=0.00..2.10
> > rows=10 width=13) (actual time=0.003..0.006 rows=10 loops=1)
> > -> Index Scan
> > using crm_origin_pkey on crm_origin co (cost=0.14..0.16 rows=1
> > width=19) (actual time=0.004..0.004 rows=1 loops=7359)
> > Index Cond:
> > (id = ws.how_meet_enercoop)
> > -> Index Scan using
> > contact_contact_pkey on contact_contact mc (cost=0.42..0.65 rows=1
> > width=150) (actual time=0.007..0.008 rows=1 loops=7359)
> > Index Cond:
> > (partner.main_contact = id)
> > -> Index Scan using
> > contact_title_pkey on contact_title title (cost=0.14..0.16 rows=1
> > width=42) (actual time=0.003..0.003 rows=1 loops=7359)
> > Index Cond: (mc.title = id)
> > -> Index Scan using
> > contact_address_pkey on contact_address adr_contact (cost=0.43..0.70
> > rows=1 width=68) (actual time=0.005..0.005 rows=1 loops=7359)
> > Index Cond: (id = CASE WHEN
> > (CASE WHEN ((partner.person_category_select)::text =
> > 'naturalPerson'::text) THEN 'P'::text WHEN
> > ((partner.person_category_select)::text = 'legalPerson'::text) THEN
> > 'M'::text ELSE '?????'::text END = 'P'::text) THEN
> > COALESCE(mc.address, mc.address_pro) ELSE COALESCE(mc.address_pro,
> > mc.address) END)
> > -> Index Scan using
> > contact_contact_address_contact_idx on contact_contact_address cca
> > (cost=0.42..0.48 rows=1 width=24) (actual time=0.006..0.006 rows=1
> > loops=7359)
> > Index Cond: (contact = mc.id)
> > -> Index Scan using
> > contact_contact_address_status_pkey on contact_contact_address_status
> > npai (cost=0.13..0.15 rows=1 width=9) (actual time=0.000..0.000
> > rows=0 loops=7359)
> > Index Cond: (cca.contact_address_status = id)
> > -> Index Scan using
> > crm_crm_request_original_contract_line_idx on crm_crm_request
> > mesrequest (cost=0.28..0.29 rows=1 width=16) (actual
> > time=0.003..0.003 rows=0 loops=7359)
> > Index Cond: (original_contract_line =
> contractline.id)
> > -> Index Scan using sale_product_sub_family_pkey on
> > sale_product_sub_family mesproductsubfamily (cost=0.14..0.20 rows=1
> > width=62) (actual time=0.000..0.000 rows=0 loops=7359)
> > Index Cond: (id = mesrequest.product_sub_family)
> > Filter: (new_contract_ok IS TRUE)
> > Planning time: 21.106 ms
> > Execution time: 341275.027 ms
> > (118 lignes)
> >
> >
> > --
> > http://www.laurentmartelli.com // http://www.imprimart.fr
>
>
>
> --
> http://www.laurentmartelli.com // http://www.imprimart.fr
>
>