I have this schema:
 
CREATE TABLE onp_crm_person( id serial PRIMARY KEY, onp_user_id bigint 
referencesonp_user(id) deferrable initially deferred, is_resource boolean not 
null default false, UNIQUE(onp_user_id) ); CREATE TABLE onp_crm_activity_log( id
bigserial PRIMARY KEY, relation_id integer REFERENCES 
onp_crm_relation(entity_id), logged_forint references 
onp_crm_person(onp_user_id), durationbigint ); CREATE TABLE onp_crm_invoice( 
entity_idbigint PRIMARY KEY REFERENCES onp_crm_entity(entity_id), status_key 
VARCHAR NOT NULL, credit_against bigint REFERENCES onp_crm_invoice(entity_id), 
sent_dateDATE, UNIQUE(credit_against) deferrable INITIALLY DEFERRED -- 
invoice_print_template_id is added after creation of 
origo_invoice_print_template); CREATE TABLE onp_crm_invoice_line ( id SERIAL 
PRIMARY KEY, invoice_id INTEGER NOT NULL REFERENCES onp_crm_invoice (entity_id) 
);CREATE TABLE onp_crm_calendarentry_invoice_membership( invoice_line_id 
INTEGER NOT NULL REFERENCESonp_crm_invoice_line(id) ON DELETE CASCADE, 
calendar_entry_idINTEGER NOT NULL REFERENCES onp_crm_activity_log(id), unique
(invoice_line_id, calendar_entry_id)DEFERRABLE INITIALLY DEFERRED ); 
 
This query performs terribly slow ( ~26 minutes, 1561346.597ms):
 
explain analyze SELECT  log.relation_id as company_id , sum(log.duration) AS 
durationFROM onp_crm_activity_log log  JOIN onp_crm_person logfor ON 
logfor.onp_user_id =log.logged_for AND logfor.is_resource = FALSE WHERE 1 = 1 
-- Filter out already invoiced before 2016-06-27 AND NOT EXISTS( SELECT * FROM 
onp_crm_calendarentry_invoice_membership cemJOIN onp_crm_invoice_line il ON 
cem.invoice_line_id = il.idJOIN onp_crm_invoice inv ON il.invoice_id = 
inv.entity_idWHERE cem.calendar_entry_id = log.id AND inv.status_key = 
'INVOICE_STATUS_INVOICED' AND inv.sent_date <= '2016-06-27' AND NOT EXISTS( 
SELECT* FROM onp_crm_invoice creditnote WHERE il.invoice_id = 
creditnote.credit_againstAND creditnote.status_key = 'INVOICE_STATUS_INVOICED' 
ANDcreditnote.sent_date <= '2016-06-27' ) ) GROUP BY  log.relation_id ; 
 
Explain output:
                                                                              
                                       QUERY PLAN 
                                                                                
                                      
 
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 HashAggregate  (cost=13778.63..13796.39 rows=1421 width=12) (actual 
time=1561343.861..1561344.042 rows=724 loops=1)
   Group Key: log.relation_id
   ->  Nested Loop Anti Join  (cost=741.35..13768.63 rows=2000 width=12) 
(actual time=471.973..1561221.929 rows=96095 loops=1)
         Join Filter: (cem.calendar_entry_id = log.id)
         Rows Removed by Join Filter: 11895758618
         ->  Hash Join  (cost=86.56..9729.03 rows=2000 width=20) (actual 
time=0.170..668.911 rows=181644 loops=1)
               Hash Cond: (log.logged_for = logfor.onp_user_id)
               ->  Seq Scan on onp_crm_activity_log log  (cost=0.00..8930.98 
rows=184398 width=24) (actual time=0.007..538.893 rows=182378 loops=1)
               ->  Hash  (cost=39.46..39.46 rows=3768 width=8) (actual 
time=0.126..0.126 rows=36 loops=1)
                     Buckets: 4096  Batches: 1  Memory Usage: 34kB
                     ->  Bitmap Heap Scan on onp_crm_person logfor 
 (cost=3.69..39.46 rows=3768 width=8) (actual time=0.040..0.106 rows=36 loops=1)
                           Recheck Cond: (onp_user_id IS NOT NULL)
                           Filter: (NOT is_resource)
                           Rows Removed by Filter: 5
                           Heap Blocks: exact=10
                           ->  Bitmap Index Scan on onp_crm_person_onp_id_idx 
 (cost=0.00..2.75 rows=41 width=0) (actual time=0.019..0.019 rows=41 loops=1)
         ->  Materialize  (cost=654.79..4009.60 rows=1 width=4) (actual 
time=0.000..2.829 rows=65490 loops=181644)
               ->  Nested Loop  (cost=654.79..4009.59 rows=1 width=4) (actual 
time=9.056..386.835 rows=85668 loops=1)
                     ->  Nested Loop  (cost=654.50..4009.27 rows=1 width=8) 
(actual time=9.046..165.280 rows=88151 loops=1)
                           ->  Hash Anti Join  (cost=654.21..4008.72 rows=1 
width=8) (actual time=9.016..40.672 rows=76174 loops=1)
                                 Hash Cond: (il.invoice_id = 
creditnote.credit_against)
                                 ->  Seq Scan on onp_crm_invoice_line il 
 (cost=0.00..3062.01 rows=78001 width=8) (actual time=0.005..11.259 rows=78614 
loops=1)
                                 ->  Hash  (cost=510.56..510.56 rows=11492 
width=8) (actual time=8.940..8.940 rows=372 loops=1)
                                       Buckets: 16384  Batches: 1  Memory 
Usage: 143kB
                                       ->  Seq Scan on onp_crm_invoice 
creditnote  (cost=0.00..510.56 rows=11492 width=8) (actual time=0.014..7.882 
rows=11507 loops=1)
                                             Filter: ((sent_date <= 
'2016-06-27'::date) AND ((status_key)::text = 'INVOICE_STATUS_INVOICED'::text))
                                             Rows Removed by Filter: 149
                           ->  Index Only Scan using 
onp_crm_calendarentry_invoice_invoice_line_id_calendar_entr_key on 
onp_crm_calendarentry_invoice_membership cem  (cost=0.29..0.45 rows=9 width=8) 
(actual time=0.001..0.001 rows=1 loops=76174)
                                 Index Cond: (invoice_line_id = il.id)
                                 Heap Fetches: 4371
                     ->  Index Scan using onp_crm_invoice_pkey on 
onp_crm_invoice inv  (cost=0.29..0.31 rows=1 width=8) (actual time=0.002..0.002 
rows=1 loops=88151)
                           Index Cond: (entity_id = il.invoice_id)
                           Filter: ((sent_date <= '2016-06-27'::date) AND 
((status_key)::text = 'INVOICE_STATUS_INVOICED'::text))
                           Rows Removed by Filter: 0
 Planning time: 3.307 ms
 Execution time: 1561346.597 ms
 (36 rows)

  
 
Here is with set enable_nestloop to false;
                                                                              
       QUERY PLAN 
                                                                                
      
 
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 HashAggregate  (cost=15936.07..15953.83 rows=1421 width=12) (actual 
time=337.878..338.045 rows=724 loops=1)
   Group Key: log.relation_id
   ->  Hash Anti Join  (cost=6258.35..15926.07 rows=2000 width=12) (actual 
time=139.976..317.402 rows=96097 loops=1)
         Hash Cond: (log.id = cem.calendar_entry_id)
         ->  Hash Join  (cost=86.56..9729.03 rows=2000 width=20) (actual 
time=0.164..132.935 rows=181646 loops=1)
               Hash Cond: (log.logged_for = logfor.onp_user_id)
               ->  Seq Scan on onp_crm_activity_log log  (cost=0.00..8930.98 
rows=184398 width=24) (actual time=0.006..89.170 rows=182380 loops=1)
               ->  Hash  (cost=39.46..39.46 rows=3768 width=8) (actual 
time=0.118..0.118 rows=36 loops=1)
                     Buckets: 4096  Batches: 1  Memory Usage: 34kB
                     ->  Bitmap Heap Scan on onp_crm_person logfor 
 (cost=3.69..39.46 rows=3768 width=8) (actual time=0.037..0.101 rows=36 loops=1)
                           Recheck Cond: (onp_user_id IS NOT NULL)
                           Filter: (NOT is_resource)
                           Rows Removed by Filter: 5
                           Heap Blocks: exact=10
                           ->  Bitmap Index Scan on onp_crm_person_onp_id_idx 
 (cost=0.00..2.75 rows=41 width=0) (actual time=0.017..0.017 rows=41 loops=1)
         ->  Hash  (cost=6171.78..6171.78 rows=1 width=4) (actual 
time=139.779..139.779 rows=85668 loops=1)
               Buckets: 131072 (originally 1024)  Batches: 1 (originally 1) 
 Memory Usage: 4036kB
               ->  Hash Join  (cost=4562.41..6171.78 rows=1 width=4) (actual 
time=92.471..125.417 rows=85668 loops=1)
                     Hash Cond: (cem.invoice_line_id = il.id)
                     ->  Seq Scan on onp_crm_calendarentry_invoice_membership 
cem  (cost=0.00..1278.44 rows=88244 width=8) (actual time=0.005..7.941 
rows=88734 loops=1)
                     ->  Hash  (cost=4562.40..4562.40 rows=1 width=4) (actual 
time=92.444..92.444 rows=75570 loops=1)
                           Buckets: 131072 (originally 1024)  Batches: 1 
(originally 1)  Memory Usage: 3681kB
                           ->  Hash Join  (cost=4008.74..4562.40 rows=1 
width=4) (actual time=61.797..79.981 rows=75570 loops=1)
                                 Hash Cond: (inv.entity_id = il.invoice_id)
                                 ->  Seq Scan on onp_crm_invoice inv 
 (cost=0.00..510.56 rows=11492 width=8) (actual time=0.027..4.489 rows=11507 
loops=1)
                                       Filter: ((sent_date <= 
'2016-06-27'::date) AND ((status_key)::text = 'INVOICE_STATUS_INVOICED'::text))
                                       Rows Removed by Filter: 151
                                 ->  Hash  (cost=4008.72..4008.72 rows=1 
width=8) (actual time=61.751..61.751 rows=76182 loops=1)
                                       Buckets: 131072 (originally 1024) 
 Batches: 1 (originally 1)  Memory Usage: 4000kB
                                       ->  Hash Anti Join 
 (cost=654.21..4008.72 rows=1 width=8) (actual time=12.568..47.911 rows=76182 
loops=1)
                                             Hash Cond: (il.invoice_id = 
creditnote.credit_against)
                                             ->  Seq Scan on 
onp_crm_invoice_line il  (cost=0.00..3062.01 rows=78001 width=8) (actual 
time=0.008..12.476 rows=78622 loops=1)
                                             ->  Hash  (cost=510.56..510.56 
rows=11492 width=8) (actual time=12.477..12.477 rows=372 loops=1)
                                                   Buckets: 16384  Batches: 1 
 Memory Usage: 143kB
                                                   ->  Seq Scan on 
onp_crm_invoice creditnote  (cost=0.00..510.56 rows=11492 width=8) (actual 
time=0.008..10.963 rows=11507 loops=1)
                                                         Filter: ((sent_date 
<= '2016-06-27'::date) AND ((status_key)::text = 
'INVOICE_STATUS_INVOICED'::text))
                                                         Rows Removed by 
Filter: 151
 Planning time: 3.510 ms
 Execution time: 338.349 ms
 (39 rows)

 So my question is is there something I can do to make PG favor a Hash Anti 
Join instead of a Nested Loop Anti Join (which I assume is the problem)?
Can the nested NOT EXISTS be re-written to be more performant?
 
Thanks.
 
-- Andreas Joseph Krogh
CTO / Partner - Visena AS
Mobile: +47 909 56 963
andr...@visena.com <mailto:andr...@visena.com>
www.visena.com <https://www.visena.com>
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