1

I setup a new postgres database (v12) by export/importing from an old one (v9.5).

When I query the new one, it's drastically slower despite being on a more powerful machine. Shared buffers are set to 90 gb, hard drive is 500k iops m.2, 128 threads, etc.

If I run COUNT(*) on both tables, version 12 is over twice as fast. 100 million rows took 3 minutes vs 7.5 minutes.

Nothing jumps out to me from the explain query. What could be the issue?

EXPLAIN ANALYZE from Original Postgres 9.5

"Limit  (cost=1422.06..228425.22 rows=1 width=49) (actual time=0.334..2.244 rows=2097 loops=1)"
"  ->  Bitmap Heap Scan on current_nodes  (cost=1422.06..228425.22 rows=1 width=49) (actual time=0.333..2.059 rows=2097 loops=1)"
"        Recheck Cond: (((tile >= 1334380527) AND (tile <= 1334380543)) OR ((tile >= 1334381903) AND (tile <= 1334381919)) OR ((tile >= 1334381935) AND (tile <= 1334381951)) OR ((tile >= 1334382032) AND (tile <= 1334382033)) OR ((tile >= 1334382036) AND (tile <= 1334382037)) OR ((tile >= 1334383264) AND (tile <= 1334383295)) OR ((tile >= 1334383328) AND (tile <= 1334383359)) OR ((tile >= 1334383520) AND (tile <= 1334383535)) OR ((tile >= 1334384640) AND (tile <= 1334384769)) OR ((tile >= 1334384772) AND (tile <= 1334384773)) OR ((tile >= 1334384784) AND (tile <= 1334384785)) OR ((tile >= 1334384788) AND (tile <= 1334384789)) OR ((tile >= 1334384832) AND (tile <= 1334384833)) OR ((tile >= 1334384836) AND (tile <= 1334384837)) OR ((tile >= 1334384848) AND (tile <= 1334384849)) OR ((tile >= 1334384852) AND (tile <= 1334384853)) OR ((tile >= 1334384896) AND (tile <= 1334384911)) OR ((tile >= 1334384928) AND (tile <= 1334384943)) OR ((tile >= 1334385024) AND (tile <= 1334385025)) OR ((tile >= 1334385028) AND (tile <= 1334385029)) OR (tile = ANY ('{1334380517,1334380519,1334380525,1334381893,1334381895,1334381901,1334381925,1334381927,1334381933,1334382021}'::bigint[])))"
"        Filter: (((latitude)::numeric >= 346183300.0) AND ((latitude)::numeric <= 346816700.00000006) AND ((longitude)::numeric >= '-982816700.0'::numeric) AND ((longitude)::numeric <= '-982183300.0'::numeric))"
"        Rows Removed by Filter: 286"
"        Heap Blocks: exact=204"
"        ->  BitmapOr  (cost=1422.06..1422.06 rows=57888 width=0) (actual time=0.299..0.299 rows=0 loops=1)"
"              ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..11.74 rows=317 width=0) (actual time=0.034..0.034 rows=197 loops=1)"
"                    Index Cond: ((tile >= 1334380527) AND (tile <= 1334380543))"
"              ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..11.74 rows=317 width=0) (actual time=0.016..0.016 rows=183 loops=1)"
"                    Index Cond: ((tile >= 1334381903) AND (tile <= 1334381919))"
"              ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..11.74 rows=317 width=0) (actual time=0.023..0.023 rows=226 loops=1)"
"                    Index Cond: ((tile >= 1334381935) AND (tile <= 1334381951))"
"              ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..4.78 rows=20 width=0) (actual time=0.004..0.004 rows=11 loops=1)"
"                    Index Cond: ((tile >= 1334382032) AND (tile <= 1334382033))"
"              ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..4.78 rows=20 width=0) (actual time=0.002..0.002 rows=11 loops=1)"
"                    Index Cond: ((tile >= 1334382036) AND (tile <= 1334382037))"
"              ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..18.71 rows=614 width=0) (actual time=0.025..0.025 rows=307 loops=1)"
"                    Index Cond: ((tile >= 1334383264) AND (tile <= 1334383295))"
"              ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..18.71 rows=614 width=0) (actual time=0.017..0.017 rows=232 loops=1)"
"                    Index Cond: ((tile >= 1334383328) AND (tile <= 1334383359))"
"              ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..11.54 rows=297 width=0) (actual time=0.016..0.016 rows=86 loops=1)"
"                    Index Cond: ((tile >= 1334383520) AND (tile <= 1334383535))"
"              ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..66.11 rows=2553 width=0) (actual time=0.102..0.102 rows=1411 loops=1)"
"                    Index Cond: ((tile >= 1334384640) AND (tile <= 1334384769))"
"              ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..4.78 rows=20 width=0) (actual time=0.002..0.002 rows=0 loops=1)"
"                    Index Cond: ((tile >= 1334384772) AND (tile <= 1334384773))"
"              ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..4.78 rows=20 width=0) (actual time=0.003..0.003 rows=11 loops=1)"
"                    Index Cond: ((tile >= 1334384784) AND (tile <= 1334384785))"
"              ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..4.78 rows=20 width=0) (actual time=0.004..0.004 rows=18 loops=1)"
"                    Index Cond: ((tile >= 1334384788) AND (tile <= 1334384789))"
"              ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..4.78 rows=20 width=0) (actual time=0.004..0.004 rows=14 loops=1)"
"                    Index Cond: ((tile >= 1334384832) AND (tile <= 1334384833))"
"              ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..4.78 rows=20 width=0) (actual time=0.002..0.002 rows=0 loops=1)"
"                    Index Cond: ((tile >= 1334384836) AND (tile <= 1334384837))"
"              ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..4.78 rows=20 width=0) (actual time=0.002..0.002 rows=7 loops=1)"
"                    Index Cond: ((tile >= 1334384848) AND (tile <= 1334384849))"
"              ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..4.78 rows=20 width=0) (actual time=0.003..0.003 rows=0 loops=1)"
"                    Index Cond: ((tile >= 1334384852) AND (tile <= 1334384853))"
"              ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..11.54 rows=297 width=0) (actual time=0.004..0.004 rows=34 loops=1)"
"                    Index Cond: ((tile >= 1334384896) AND (tile <= 1334384911))"
"              ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..11.54 rows=297 width=0) (actual time=0.010..0.010 rows=117 loops=1)"
"                    Index Cond: ((tile >= 1334384928) AND (tile <= 1334384943))"
"              ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..4.78 rows=20 width=0) (actual time=0.003..0.003 rows=0 loops=1)"
"                    Index Cond: ((tile >= 1334385024) AND (tile <= 1334385025))"
"              ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..4.78 rows=20 width=0) (actual time=0.003..0.003 rows=11 loops=1)"
"                    Index Cond: ((tile >= 1334385028) AND (tile <= 1334385029))"
"              ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..1196.12 rows=52049 width=0) (actual time=0.020..0.020 rows=74 loops=1)"
"                    Index Cond: (tile = ANY ('{1334380517,1334380519,1334380525,1334381893,1334381895,1334381901,1334381925,1334381927,1334381933,1334382021}'::bigint[]))"
"Planning time: 0.417 ms"
"Execution time: 2.489 ms"

Postgres 12 EXPLAIN ANALYZE

 Limit  (cost=4140.05..565609.02 rows=4 width=49) (actual time=76.641..114.425 rows=2097 loops=1)
   ->  Gather  (cost=4140.05..565609.02 rows=4 width=49) (actual time=0.713..38.404 rows=2097 loops=1)
         Workers Planned: 2
         Workers Launched: 2
         ->  Parallel Bitmap Heap Scan on current_nodes  (cost=3140.05..564608.62 rows=2 width=49) (actual time=0.127..0.389 rows=699 loops=3)
               Recheck Cond: (((tile >= 1334380527) AND (tile <= 1334380543)) OR ((tile >= 1334381903) AND (tile <= 1334381919)) OR ((tile >= 1334381935) AND (tile <= 1334381951)) OR ((tile >= 1334382032) AND (tile <= 1334382033)) OR ((tile >= 1334382036) AND (tile <= 1334382037)) OR ((tile >= 1334383264) AND (tile <= 1334383295)) OR ((tile >= 1334383328) AND (tile <= 1334383359)) OR ((tile >= 1334383520) AND (tile <= 1334383535)) OR ((tile >= 1334384640) AND (tile <= 1334384769)) OR ((tile >= 1334384772) AND (tile <= 1334384773)) OR ((tile >= 1334384784) AND (tile <= 1334384785)) OR ((tile >= 1334384788) AND (tile <= 1334384789)) OR ((tile >= 1334384832) AND (tile <= 1334384833)) OR ((tile >= 1334384836) AND (tile <= 1334384837)) OR ((tile >= 1334384848) AND (tile <= 1334384849)) OR ((tile >= 1334384852) AND (tile <= 1334384853)) OR ((tile >= 1334384896) AND (tile <= 1334384911)) OR ((tile >= 1334384928) AND (tile <= 1334384943)) OR ((tile >= 1334385024) AND (tile <= 1334385025)) OR ((tile >= 1334385028) AND (tile <= 1334385029)) OR (tile = ANY ('{1334380517,1334380519,1334380525,1334381893,1334381895,1334381901,1334381925,1334381927,1334381933,1334382021}'::bigint[])))
               Filter: (((latitude)::numeric >= 346183300.0) AND ((latitude)::numeric <= 346816700.00000006) AND ((longitude)::numeric >= '-982816700.0'::numeric) AND ((longitude)::numeric <= '-982183300.0'::numeric))
               Rows Removed by Filter: 95
               Heap Blocks: exact=189
               ->  BitmapOr  (cost=3140.05..3140.05 rows=152916 width=0) (actual time=0.332..0.335 rows=0 loops=1)
                     ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..111.80 rows=5122 width=0) (actual time=0.216..0.216 rows=191 loops=1)
                           Index Cond: ((tile >= 1334380527) AND (tile <= 1334380543))
                     ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..111.80 rows=5122 width=0) (actual time=0.009..0.009 rows=180 loops=1)
                           Index Cond: ((tile >= 1334381903) AND (tile <= 1334381919))
                     ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..111.80 rows=5122 width=0) (actual time=0.006..0.006 rows=154 loops=1)
                           Index Cond: ((tile >= 1334381935) AND (tile <= 1334381951))
                     ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..107.20 rows=5062 width=0) (actual time=0.003..0.003 rows=11 loops=1)
                           Index Cond: ((tile >= 1334382032) AND (tile <= 1334382033))
                     ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..107.20 rows=5062 width=0) (actual time=0.002..0.002 rows=11 loops=1)
                           Index Cond: ((tile >= 1334382036) AND (tile <= 1334382037))
                     ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..112.39 rows=5182 width=0) (actual time=0.011..0.011 rows=286 loops=1)
                           Index Cond: ((tile >= 1334383264) AND (tile <= 1334383295))
                     ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..112.39 rows=5182 width=0) (actual time=0.008..0.008 rows=219 loops=1)
                           Index Cond: ((tile >= 1334383328) AND (tile <= 1334383359))
                     ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..111.76 rows=5118 width=0) (actual time=0.007..0.007 rows=81 loops=1)
                           Index Cond: ((tile >= 1334383520) AND (tile <= 1334383535))
                     ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..120.35 rows=5577 width=0) (actual time=0.035..0.035 rows=1042 loops=1)
                           Index Cond: ((tile >= 1334384640) AND (tile <= 1334384769))
                     ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..107.20 rows=5062 width=0) (actual time=0.001..0.001 rows=0 loops=1)
                           Index Cond: ((tile >= 1334384772) AND (tile <= 1334384773))
                     ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..107.20 rows=5062 width=0) (actual time=0.001..0.001 rows=11 loops=1)
                           Index Cond: ((tile >= 1334384784) AND (tile <= 1334384785))
                     ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..107.20 rows=5062 width=0) (actual time=0.002..0.002 rows=18 loops=1)
                           Index Cond: ((tile >= 1334384788) AND (tile <= 1334384789))
                     ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..107.20 rows=5062 width=0) (actual time=0.003..0.003 rows=7 loops=1)
                           Index Cond: ((tile >= 1334384832) AND (tile <= 1334384833))
                     ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..107.20 rows=5062 width=0) (actual time=0.001..0.001 rows=0 loops=1)
                           Index Cond: ((tile >= 1334384836) AND (tile <= 1334384837))
                     ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..107.20 rows=5062 width=0) (actual time=0.001..0.002 rows=4 loops=1)
                           Index Cond: ((tile >= 1334384848) AND (tile <= 1334384849))
                     ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..107.20 rows=5062 width=0) (actual time=0.001..0.001 rows=0 loops=1)
                           Index Cond: ((tile >= 1334384852) AND (tile <= 1334384853))
                     ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..111.76 rows=5118 width=0) (actual time=0.003..0.003 rows=28 loops=1)
                           Index Cond: ((tile >= 1334384896) AND (tile <= 1334384911))
                     ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..111.76 rows=5118 width=0) (actual time=0.004..0.004 rows=68 loops=1)
                           Index Cond: ((tile >= 1334384928) AND (tile <= 1334384943))
                     ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..107.20 rows=5062 width=0) (actual time=0.002..0.002 rows=0 loops=1)
                           Index Cond: ((tile >= 1334385024) AND (tile <= 1334385025))
                     ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..107.20 rows=5062 width=0) (actual time=0.002..0.002 rows=11 loops=1)
                           Index Cond: ((tile >= 1334385028) AND (tile <= 1334385029))
                     ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..945.10 rows=50576 width=0) (actual time=0.013..0.013 rows=61 loops=1)
                           Index Cond: (tile = ANY ('{1334380517,1334380519,1334380525,1334381893,1334381895,1334381901,1334381925,1334381927,1334381933,1334382021}'::bigint[]))
 Planning Time: 0.338 ms
 JIT:
   Functions: 13
   Options: Inlining true, Optimization true, Expressions true, Deforming true
   Timing: Generation 4.516 ms, Inlining 4.039 ms, Optimization 43.691 ms, Emission 28.069 ms, Total 80.315 ms
 Execution Time: 116.372 ms

Edit: I disabled JIT, which improved it, but it's still significantly slower.

"Limit  (cost=4140.05..565609.02 rows=4 width=49) (actual time=1.434..36.111 rows=2097 loops=1)"
"  ->  Gather  (cost=4140.05..565609.02 rows=4 width=49) (actual time=1.433..35.884 rows=2097 loops=1)"
"        Workers Planned: 2"
"        Workers Launched: 2"
"        ->  Parallel Bitmap Heap Scan on current_nodes  (cost=3140.05..564608.62 rows=2 width=49) (actual time=0.219..0.905 rows=699 loops=3)"
"              Recheck Cond: (((tile >= 1334380527) AND (tile <= 1334380543)) OR ((tile >= 1334381903) AND (tile <= 1334381919)) OR ((tile >= 1334381935) AND (tile <= 1334381951)) OR ((tile >= 1334382032) AND (tile <= 1334382033)) OR ((tile >= 1334382036) AND (tile <= 1334382037)) OR ((tile >= 1334383264) AND (tile <= 1334383295)) OR ((tile >= 1334383328) AND (tile <= 1334383359)) OR ((tile >= 1334383520) AND (tile <= 1334383535)) OR ((tile >= 1334384640) AND (tile <= 1334384769)) OR ((tile >= 1334384772) AND (tile <= 1334384773)) OR ((tile >= 1334384784) AND (tile <= 1334384785)) OR ((tile >= 1334384788) AND (tile <= 1334384789)) OR ((tile >= 1334384832) AND (tile <= 1334384833)) OR ((tile >= 1334384836) AND (tile <= 1334384837)) OR ((tile >= 1334384848) AND (tile <= 1334384849)) OR ((tile >= 1334384852) AND (tile <= 1334384853)) OR ((tile >= 1334384896) AND (tile <= 1334384911)) OR ((tile >= 1334384928) AND (tile <= 1334384943)) OR ((tile >= 1334385024) AND (tile <= 1334385025)) OR ((tile >= 1334385028) AND (tile <= 1334385029)) OR (tile = ANY ('{1334380517,1334380519,1334380525,1334381893,1334381895,1334381901,1334381925,1334381927,1334381933,1334382021}'::bigint[])))"
"              Filter: (((latitude)::numeric >= 346183300.0) AND ((latitude)::numeric <= 346816700.00000006) AND ((longitude)::numeric >= '-982816700.0'::numeric) AND ((longitude)::numeric <= '-982183300.0'::numeric))"
"              Rows Removed by Filter: 95"
"              Heap Blocks: exact=189"
"              ->  BitmapOr  (cost=3140.05..3140.05 rows=152916 width=0) (actual time=0.577..0.580 rows=0 loops=1)"
"                    ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..111.80 rows=5122 width=0) (actual time=0.323..0.323 rows=191 loops=1)"
"                          Index Cond: ((tile >= 1334380527) AND (tile <= 1334380543))"
"                    ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..111.80 rows=5122 width=0) (actual time=0.018..0.018 rows=180 loops=1)"
"                          Index Cond: ((tile >= 1334381903) AND (tile <= 1334381919))"
"                    ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..111.80 rows=5122 width=0) (actual time=0.013..0.013 rows=154 loops=1)"
"                          Index Cond: ((tile >= 1334381935) AND (tile <= 1334381951))"
"                    ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..107.20 rows=5062 width=0) (actual time=0.005..0.005 rows=11 loops=1)"
"                          Index Cond: ((tile >= 1334382032) AND (tile <= 1334382033))"
"                    ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..107.20 rows=5062 width=0) (actual time=0.003..0.004 rows=11 loops=1)"
"                          Index Cond: ((tile >= 1334382036) AND (tile <= 1334382037))"
"                    ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..112.39 rows=5182 width=0) (actual time=0.023..0.023 rows=286 loops=1)"
"                          Index Cond: ((tile >= 1334383264) AND (tile <= 1334383295))"
"                    ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..112.39 rows=5182 width=0) (actual time=0.017..0.017 rows=219 loops=1)"
"                          Index Cond: ((tile >= 1334383328) AND (tile <= 1334383359))"
"                    ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..111.76 rows=5118 width=0) (actual time=0.011..0.011 rows=81 loops=1)"
"                          Index Cond: ((tile >= 1334383520) AND (tile <= 1334383535))"
"                    ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..120.35 rows=5577 width=0) (actual time=0.076..0.076 rows=1042 loops=1)"
"                          Index Cond: ((tile >= 1334384640) AND (tile <= 1334384769))"
"                    ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..107.20 rows=5062 width=0) (actual time=0.003..0.003 rows=0 loops=1)"
"                          Index Cond: ((tile >= 1334384772) AND (tile <= 1334384773))"
"                    ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..107.20 rows=5062 width=0) (actual time=0.004..0.004 rows=11 loops=1)"
"                          Index Cond: ((tile >= 1334384784) AND (tile <= 1334384785))"
"                    ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..107.20 rows=5062 width=0) (actual time=0.004..0.004 rows=18 loops=1)"
"                          Index Cond: ((tile >= 1334384788) AND (tile <= 1334384789))"
"                    ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..107.20 rows=5062 width=0) (actual time=0.004..0.004 rows=7 loops=1)"
"                          Index Cond: ((tile >= 1334384832) AND (tile <= 1334384833))"
"                    ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..107.20 rows=5062 width=0) (actual time=0.003..0.003 rows=0 loops=1)"
"                          Index Cond: ((tile >= 1334384836) AND (tile <= 1334384837))"
"                    ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..107.20 rows=5062 width=0) (actual time=0.003..0.003 rows=4 loops=1)"
"                          Index Cond: ((tile >= 1334384848) AND (tile <= 1334384849))"
"                    ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..107.20 rows=5062 width=0) (actual time=0.002..0.002 rows=0 loops=1)"
"                          Index Cond: ((tile >= 1334384852) AND (tile <= 1334384853))"
"                    ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..111.76 rows=5118 width=0) (actual time=0.007..0.007 rows=28 loops=1)"
"                          Index Cond: ((tile >= 1334384896) AND (tile <= 1334384911))"
"                    ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..111.76 rows=5118 width=0) (actual time=0.008..0.008 rows=68 loops=1)"
"                          Index Cond: ((tile >= 1334384928) AND (tile <= 1334384943))"
"                    ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..107.20 rows=5062 width=0) (actual time=0.004..0.004 rows=0 loops=1)"
"                          Index Cond: ((tile >= 1334385024) AND (tile <= 1334385025))"
"                    ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..107.20 rows=5062 width=0) (actual time=0.003..0.003 rows=11 loops=1)"
"                          Index Cond: ((tile >= 1334385028) AND (tile <= 1334385029))"
"                    ->  Bitmap Index Scan on current_nodes_tile_idx  (cost=0.00..945.10 rows=50576 width=0) (actual time=0.040..0.040 rows=61 loops=1)"
"                          Index Cond: (tile = ANY ('{1334380517,1334380519,1334380525,1334381893,1334381895,1334381901,1334381925,1334381927,1334381933,1334382021}'::bigint[]))"
"Planning Time: 0.376 ms"
"Execution Time: 36.307 ms"
4
  • Did you analyze all tables after the import? Nov 24, 2020 at 22:00
  • as @a_horse_with_no_name said update stats using analyze and make sure indexes are not corrupted , maybe do a reindex
    – eshirvana
    Nov 24, 2020 at 22:34
  • by the way I just noticed , the execution plan on Postgres 12 shows it went parallel and apparently It made it worse , where in Postgres 9 it went single threaded.
    – eshirvana
    Nov 24, 2020 at 22:38
  • so for some reason Postgres though It's too much work and It needs to go parallel, so you have to find out why, maybe paste the EXPLAIN (ANALYZE, COSTS, VERBOSE, BUFFERS, FORMAT)
    – eshirvana
    Nov 24, 2020 at 22:47

3 Answers 3

2

the execution plan on Postgres 12 shows it went parallel and apparently It made it worse , where in Postgres 9 it went single threaded. seems like postgres overestimated in every single step and eventually thought that is too much work and consequently it went parallel and made a huge scene for nothing.

probably If you update your stats and probably rebuild your index ( just in case) you will be fine

1

I'd say that the problem is that during the Gather phase, PostgreSQL has to move about 1400 rows between the parallel workers and the leader instead of the expected one ot two.

Try setting max_parallel_workers_per_gather to 0 and see if the query gets faster.

If that helps, you could ANALYZE the table and see if the estimates become more realistic and discourage PostgreSQL from using a parallel plan. If that alone is not enough, you might need to increase default_statistics_target and ANALYZE again to get more detailed statistics for that table.

0

The main issue was the database needed to have VACUUM run on it. I'm surprised that a full database export/import wouldn't just automatically do it considering the performance gain was 100x faster.

  1. Run VACUUM on the database (100x performance gain)
  2. Disable JIT in the config when running many fast SQL queries (30% performance gain for me)
  3. I did ANALYZE the database, but I failed to check performance gain. Sorry!

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