Re: 3000x Slower query when using Foreign Data Wrapper vs. local

Awesome ! Thank you very much, that solved it :) . But, do you have any
idea why this isn't enabled by default ?
As a first time user for FDW I would assume that usage of remote estimates
would be enabled by default because they would be more authoritative and
more representative of access patterns. Correct ?

Best Regards,
Mohammad

On Sun, Oct 11, 2015 at 5:42 PM, desmodemone <desmodemone(at)gmail(dot)com> wrote:

> Hi Mohammad,
> I think it's not enable
> "use_remote_estimate" during the creation of the foreign table
>
> http://www.postgresql.org/docs/9.4/static/postgres-fdw.html
>
> use_remote_estimate
>
> This option, which can be specified for a foreign table or a foreign
> server, controls whether postgres_fdw issues remote EXPLAIN commands to
> obtain cost estimates. A setting for a foreign table overrides any setting
> for its server, but only for that table. The default is false.
>
>
> try it
>
>
> Bye
>
>
> 2015-10-11 10:05 GMT+02:00 Mohammad Habbab <moh(dot)habbab(at)gmail(dot)com>:
>
>> Hi there,
>>
>> If it's possible, I would really appreciate any hints or help on an issue
>> I've been facing lately.
>> I'm running two instance of Postgres locally: 9.4.4 (operational db) and
>> 9.5beta1 (analytical db). I've already imported schema to analytical db and
>> while doing the following query I find very different query plans being
>> executed:
>>
>> Query:
>>
>> EXPLAIN ANALYZE VERBOSE SELECT
>> o.id AS id,
>> o.company_id AS company_id,
>> o.created_at::date AS created_at,
>> COALESCE(o.assignee_id, 0) AS assignee_id,
>> (o.tax_treatment)::text AS tax_treatment,
>> COALESCE(o.tax_override, 0) AS tax_override,
>> COALESCE(o.stock_location_id, 0) AS stock_location_id,
>> COALESCE(l.label, 'N/A')::text AS stock_location_name,
>> COALESCE(sa.country, 'N/A')::text AS shipping_address_country,
>> COALESCE(o.tags, ARRAY[]::text[]) AS tags
>> FROM orders AS o
>> INNER JOIN locations AS l ON l.id = o.stock_location_id
>> INNER JOIN addresses AS sa ON sa.id = o.shipping_address_id
>> WHERE o.account_id = <some_value> AND l.account_id = <another_value>
>> LIMIT 10;
>>
>>
>> Plan when I run it locally on operational db:
>>
>> Limit (cost=747.62..811.46 rows=1 width=76) (actual time=28.208..28.397
>> rows=10 loops=1)
>> Output: o.id, o.company_id, ((o.created_at)::date),
>> (COALESCE(o.assignee_id, 0)), ((o.tax_treatment)::text),
>> (COALESCE(o.tax_override, 0::numeric)), (COALESCE(o.stock_location_id, 0)),
>> ((COALESCE(l.label, 'N/A'::character varying))::text),
>> ((COALESCE(sa.country, 'N/A'::character varying))::text), (COALESCE(o.tags,
>> '{}'::character varying[]))
>> -> Nested Loop (cost=747.62..811.46 rows=1 width=76) (actual
>> time=28.208..28.395 rows=10 loops=1)
>> Output: o.id, o.company_id, (o.created_at)::date,
>> COALESCE(o.assignee_id, 0), (o.tax_treatment)::text,
>> COALESCE(o.tax_override, 0::numeric), COALESCE(o.stock_location_id, 0),
>> (COALESCE(l.label, 'N/A'::character varying))::text, (COALESCE(sa.country,
>> 'N/A'::character varying))::text, COALESCE(o.tags, '{}'::character
>> varying[])
>> -> Nested Loop (cost=747.19..807.15 rows=1 width=73) (actual
>> time=28.164..28.211 rows=10 loops=1)
>> Output: o.id, o.company_id, o.created_at, o.assignee_id,
>> o.tax_treatment, o.tax_override, o.stock_location_id, o.tags,
>> o.shipping_address_id, l.label
>> -> Index Scan using index_locations_on_account_id on
>> public.locations l (cost=0.29..8.31 rows=1 width=20) (actual
>> time=0.025..0.025 rows=1 loops=1)
>> Output: l.id, l.address1, l.address2, l.city,
>> l.country, l.zip_code, l.suburb, l.state, l.label, l.status, l.latitude,
>> l.longitude, l.created_at, l.updated_at, l.account_id, l.holds_stock
>> Index Cond: (l.account_id = 18799)
>> -> Bitmap Heap Scan on public.orders o (cost=746.90..798.71
>> rows=13 width=57) (actual time=28.133..28.176 rows=10 loops=1)
>> Output: o.id, o.account_id, o.company_id, o.status,
>> o.invoice_number, o.reference_number, o.due_at, o.issued_at, o.user_id,
>> o.notes, o.created_at, o.updated_at, o.order_number, o.billing_address_id,
>> o.shipping_address_id, o.payment_status, o.email, o.fulfillment_status,
>> o.phone_number, o.assignee_id, o.tax_treatment, o.tax_override,
>> o.tax_label_override, o.stock_location_id, o.currency_id, o.source,
>> o.source_url, o.demo, o.invoice_status, o.ship_at, o.source_id, o.search,
>> o.default_price_list_id, o.contact_id, o.return_status, o.tags,
>> o.packed_status, o.returning_status, o.shippability_status,
>> o.backordering_status
>> Recheck Cond: ((o.stock_location_id = l.id) AND
>> (o.account_id = 18799))
>> Heap Blocks: exact=7
>> -> BitmapAnd (cost=746.90..746.90 rows=13 width=0)
>> (actual time=23.134..23.134 rows=0 loops=1)
>> -> Bitmap Index Scan on
>> index_orders_on_stock_location_id_manual (cost=0.00..18.02 rows=745
>> width=0) (actual time=9.282..9.282 rows=40317 loops=1)
>> Index Cond: (o.stock_location_id = l.id)
>> -> Bitmap Index Scan on
>> index_orders_on_account_id (cost=0.00..718.94 rows=38735 width=0) (actual
>> time=9.856..9.856 rows=40317 loops=1)
>> Index Cond: (o.account_id = 18799)
>> -> Index Scan using addresses_pkey on public.addresses sa
>> (cost=0.43..4.30 rows=1 width=11) (actual time=0.015..0.016 rows=1
>> loops=10)
>> Output: sa.id, sa.company_id, sa.address1, sa.city,
>> sa.country, sa.zip_code, sa.created_at, sa.updated_at, sa.suburb, sa.state,
>> sa.label, sa.status, sa.address2, sa.phone_number, sa.email,
>> sa.company_name, sa.latitude, sa.longitude, sa.first_name, sa.last_name
>> Index Cond: (sa.id = o.shipping_address_id)
>> Planning time: 1.136 ms
>> Execution time: 28.621 ms
>> (23 rows)
>>
>> Plan when I run it from analytical db via FDW:
>>
>> Limit (cost=300.00..339.95 rows=1 width=1620) (actual
>> time=7630.240..82368.326 rows=10 loops=1)
>> Output: o.id, o.company_id, ((o.created_at)::date),
>> (COALESCE(o.assignee_id, 0)), ((o.tax_treatment)::text),
>> (COALESCE(o.tax_override, '0'::numeric)), (COALESCE(o.stock_location_id,
>> 0)), ((COALESCE(l.label, 'N/A'::character varying))::
>> text), ((COALESCE(sa.country, 'N/A'::character varying))::text),
>> (COALESCE(o.tags, '{}'::character varying[]))
>> -> Nested Loop (cost=300.00..339.95 rows=1 width=1620) (actual
>> time=7630.238..82368.314 rows=10 loops=1)
>> Output: o.id, o.company_id, (o.created_at)::date,
>> COALESCE(o.assignee_id, 0), (o.tax_treatment)::text,
>> COALESCE(o.tax_override, '0'::numeric), COALESCE(o.stock_location_id, 0),
>> (COALESCE(l.label, 'N/A'::character varying))::text,
>> (COALESCE(sa.country, 'N/A'::character varying))::text, COALESCE(o.tags,
>> '{}'::character varying[])
>> Join Filter: (o.shipping_address_id = sa.id)
>> Rows Removed by Join Filter: 19227526
>> -> Nested Loop (cost=200.00..223.58 rows=1 width=1108) (actual
>> time=69.758..69.812 rows=10 loops=1)
>> Output: o.id, o.company_id, o.created_at, o.assignee_id,
>> o.tax_treatment, o.tax_override, o.stock_location_id, o.tags,
>> o.shipping_address_id, l.label
>> Join Filter: (o.stock_location_id = l.id)
>> Rows Removed by Join Filter: 18
>> -> Foreign Scan on remote.orders o (cost=100.00..111.67
>> rows=1 width=592) (actual time=68.009..68.014 rows=10 loops=1)
>> Output: o.id, o.account_id, o.company_id, o.status,
>> o.invoice_number, o.reference_number, o.due_at, o.issued_at, o.user_id,
>> o.notes, o.created_at, o.updated_at, o.order_number, o.billing_address_id,
>> o.shipping_address
>> _id, o.payment_status, o.email, o.fulfillment_status, o.phone_number,
>> o.assignee_id, o.tax_treatment, o.tax_override, o.tax_label_override,
>> o.stock_location_id, o.currency_id, o.source, o.source_url, o.demo,
>> o.invoice_status, o.ship_at, o
>> .source_id, o.search, o.default_price_list_id, o.contact_id,
>> o.return_status, o.tags, o.packed_status, o.returning_status,
>> o.shippability_status, o.backordering_status
>> Remote SQL: SELECT id, company_id, created_at,
>> shipping_address_id, assignee_id, tax_treatment, tax_override,
>> stock_location_id, tags FROM public.orders WHERE ((account_id = 18799))
>> -> Foreign Scan on remote.locations l
>> (cost=100.00..111.90 rows=1 width=520) (actual time=0.174..0.174 rows=3
>> loops=10)
>> Output: l.id, l.address1, l.address2, l.city,
>> l.country, l.zip_code, l.suburb, l.state, l.label, l.status, l.latitude,
>> l.longitude, l.created_at, l.updated_at, l.account_id, l.holds_stock
>> Remote SQL: SELECT id, label FROM public.locations
>> WHERE ((account_id = 18799))
>> -> Foreign Scan on remote.addresses sa (cost=100.00..114.50
>> rows=150 width=520) (actual time=0.634..8029.415 rows=1922754 loops=10)
>> Output: sa.id, sa.company_id, sa.address1, sa.city,
>> sa.country, sa.zip_code, sa.created_at, sa.updated_at, sa.suburb, sa.state,
>> sa.label, sa.status, sa.address2, sa.phone_number, sa.email,
>> sa.company_name, sa.latitude, sa.l
>> ongitude, sa.first_name, sa.last_name
>> Remote SQL: SELECT id, country FROM public.addresses
>> Planning time: 0.209 ms
>> Execution time: 82391.610 ms
>> (21 rows)
>>
>> Time: 82393.211 ms
>>
>> What am I doing wrong ? really appreciate any guidance possible. Thank
>> you very much for taking the time to helping me with this.
>>
>> Best Regards,
>> Mohammad
>>
>
>
>
> --
> Matteo Durighetto
>
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--
Mohammad Habbab
Bangsar, KL, Malaysia
Mobile No. +601111582144
Email: moh(dot)habbab(at)gmail(dot)com
LinkedIn: https://www.linkedin.com/in/mohammadhabbab