Re: [GENERAL] query not scaling - Mailing list pgsql-general

Laurenz Albe <laurenz.albe@cybertec.at> writes:

Also, to have PostgreSQL inline the function, which would be good
for performance, it should be declared IMMUTABLE.

Actually, if you hope to have a SQL function be inlined, it's better
not to decorate it at all --- not with IMMUTABLE, and not with STRICT
either.  Both of those restrict the parser's ability to inline unless
it can prove the contained expression is equally immutable/strict.
With the default attributes of volatile/not strict, there's nothing
to prove.

(In any case, it's usually easy enough to tell from EXPLAIN output
whether inlining has happened.)
		regards, tom lane

                                                                                    QUERY PLAN                                                                                   
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 HashAggregate  (cost=82122076.59..82122225.35 rows=14876 width=48) (actual time=208203.091..208210.348 rows=14645 loops=1)
   Output: m.id, min(((1.0 * (((s.events_greater + s.events_equal) + 0))::numeric) / ((((s.events_less + s.events_equal) + s.events_greater) + 0))::numeric))
   Group Key: m.id
   Buffers: shared hit=43209090
   ->  Nested Loop  (cost=3799.40..44686205.23 rows=1361304413 width=40) (actual time=55.443..89684.451 rows=75577302 loops=1)
         Output: m.id, s.events_greater, s.events_equal, s.events_less
         Buffers: shared hit=43209090
         ->  Hash Join  (cost=3798.98..43611.56 rows=823591 width=32) (actual time=55.393..1397.509 rows=823591 loops=1)
               Output: s.events_greater, s.events_equal, s.events_less, s.startbase, s.endbase
               Inner Unique: true
               Hash Cond: (s.probandset_id = p.id)
               Buffers: shared hit=19222
               ->  Seq Scan on sui.segment s  (cost=0.00..29414.86 rows=823591 width=48) (actual time=0.017..669.915 rows=823591 loops=1)
                     Output: s.id, s.chrom, s.markerset_id, s.probandset_id, s.startbase, s.endbase, s.firstmarker, s.lastmarker, s.events_less, s.events_equal, s.events_greater
                     Filter: ((s.chrom = 22) AND (s.markerset_id = 'edf95066-24d2-4ca1-bad6-aa850cc82fef'::uuid))
                     Buffers: shared hit=17061
               ->  Hash  (cost=2979.99..2979.99 rows=65519 width=16) (actual time=55.272..55.272 rows=65519 loops=1)
                     Output: p.id
                     Buckets: 65536  Batches: 1  Memory Usage: 3584kB
                     Buffers: shared hit=2161
                     ->  Seq Scan on sui.probandset p  (cost=0.00..2979.99 rows=65519 width=16) (actual time=0.007..33.582 rows=65519 loops=1)
                           Output: p.id
                           Filter: (p.people_id = '9b2308b1-9659-4a2c-91ae-8f95cd0a90b3'::uuid)
                           Buffers: shared hit=2161
         ->  Index Scan using marker_chrom_basepos_idx on base.marker m  (cost=0.42..37.67 rows=1653 width=20) (actual time=0.010..0.075 rows=92 loops=823591)
               Output: m.id, m.name, m.chrom, m.basepos, m.alleles
               Index Cond: ((m.chrom = 22) AND (m.basepos >= s.startbase) AND (m.basepos <= s.endbase))
               Buffers: shared hit=43189868
 Planning time: 0.764 ms
 Execution time: 208214.816 ms
(30 rows)