Am 29.08.2018 um 12:50 schrieb Andreas Kretschmer:
Okay, other solution. The problem is the nested loop, we can disable
that:
oh, i used PG 10, this time 9.5:
test=# explain analyse SELECT *
FROM app
JOIN group_span ON
app.group_id = group_span.group_id AND
app.app_time <@ group_span.valid_period
JOIN member_span ON
group_span.group_id = member_span.group_id AND
group_span.valid_period && member_span.valid_period;
QUERY PLAN
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Nested Loop (cost=0.55..4740.90 rows=180 width=212) (actual
time=2.915..17624.676 rows=10000 loops=1)
Join Filter: (app.group_id = member_span.group_id)
-> Nested Loop (cost=0.28..4472.00 rows=600 width=112) (actual
time=0.292..347.838 rows=10000 loops=1)
-> Seq Scan on app (cost=0.00..194.00 rows=10000 width=44)
(actual time=0.012..2.689 rows=10000 loops=1)
-> Index Scan using group_span_group_id_valid_period_excl on
group_span (cost=0.28..0.42 rows=1 width=68) (actual time=0.029..0.033
rows=1 loops=10000)
Index Cond: ((group_id = app.group_id) AND (app.app_time
<@ valid_period))
-> Index Scan using
member_span_member_id_group_id_valid_period_excl on member_span
(cost=0.28..0.44 rows=1 width=100) (actual time=0.912..1.726 rows=1
loops=10000)
Index Cond: ((group_id = group_span.group_id) AND
(group_span.valid_period && valid_period))
Planning time: 1.554 ms
Execution time: 17627.266 ms
(10 rows)
test=*# set enable_nestloop to false;
SET
test=*# explain analyse SELECT *
FROM app
JOIN group_span ON
app.group_id = group_span.group_id AND
app.app_time <@ group_span.valid_period
JOIN member_span ON
group_span.group_id = member_span.group_id AND
group_span.valid_period && member_span.valid_period;
QUERY PLAN
---------------------------------------------------------------------------------------------------------------------------------
Hash Join (cost=2383.43..14284.93 rows=180 width=212) (actual
time=42.440..63.834 rows=10000 loops=1)
Hash Cond: (app.group_id = member_span.group_id)
Join Filter: (group_span.valid_period && member_span.valid_period)
Rows Removed by Join Filter: 2000
-> Merge Join (cost=1928.43..12478.43 rows=600 width=112) (actual
time=34.068..47.954 rows=10000 loops=1)
Merge Cond: (app.group_id = group_span.group_id)
Join Filter: (app.app_time <@ group_span.valid_period)
Rows Removed by Join Filter: 2000
-> Sort (cost=858.39..883.39 rows=10000 width=44) (actual
time=15.331..17.104 rows=10000 loops=1)
Sort Key: app.group_id
Sort Method: quicksort Memory: 1166kB
-> Seq Scan on app (cost=0.00..194.00 rows=10000
width=44) (actual time=0.004..1.070 rows=10000 loops=1)
-> Sort (cost=1070.04..1100.04 rows=12000 width=68) (actual
time=18.720..20.712 rows=12000 loops=1)
Sort Key: group_span.group_id
Sort Method: quicksort Memory: 2072kB
-> Seq Scan on group_span (cost=0.00..257.00
rows=12000 width=68) (actual time=0.007..1.396 rows=12000 loops=1)
-> Hash (cost=305.00..305.00 rows=12000 width=100) (actual
time=8.198..8.198 rows=12000 loops=1)
Buckets: 16384 Batches: 1 Memory Usage: 1582kB
-> Seq Scan on member_span (cost=0.00..305.00 rows=12000
width=100) (actual time=0.011..2.783 rows=12000 loops=1)
Planning time: 0.468 ms
Execution time: 64.694 ms
(21 rows)
test=*#
Regards, Andreas
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