Here is the actual explain analyze of the query on the smaller dataset
which I have been using for the recent testing.
test=# explain analyze create table _tmp0 as select * from
( select *,
(select healpixid from idt_match as m where m.transitid=o.transitid)
as x from idt_photoobservation_small as o offset 0
) as y where x%16=0 order by x;
QUERY PLAN
p----------------------------------------------------------------------------------------------------------------------------------------------------------------------
Sort (cost=63835201.73..63835214.23 rows=5000 width=498) (actual
time=8203.041..8252.216 rows=173696 loops=1)
Sort Key: y.x
Sort Method: quicksort Memory: 182555kB
-> Subquery Scan on y (cost=0.00..63834894.54 rows=5000 width=498) (actual
time=0.102..7602.947 rows=173696 loops=1)
Filter: ((y.x % 16::bigint) = 0)
Rows Removed by Filter: 826304
-> Limit (cost=0.00..63819894.51 rows=1000002 width=490) (actual
time=0.041..7296.401 rows=1000000 loops=1)
-> Seq Scan on idt_photoobservation_small o
(cost=0.00..63819894.51 rows=1000002 width=490) (actual time=0.038..7094.555
rows=1000000 loops=1)
SubPlan 1
-> Index Scan using idt_match_transitid_idx on
idt_match m (cost=0.00..63.74 rows=1 width=8) (actual time=0.003..0.004 rows=1
loops=1000000)
Index Cond: (transitid = o.transitid)
Total runtime: 8908.631 ms
*****************************************************
Sergey E. Koposov, PhD, Research Associate
Institute of Astronomy, University of Cambridge
Madingley road, CB3 0HA, Cambridge, UK
Tel: +44-1223-337-551 Web: http://www.ast.cam.ac.uk/~koposov/
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