Re: Select count(*) on a 2B Rows Tables Takes ~20 Hours

Buffers: shared hit=72620045 read=45,297,330
I/O Timings: read=57,489,958.088
Execution time: 61,141,110.516 ms

If I'm reading this correctly, it took 57M ms out of an elapsed time of 61M
ms to read 45M pages from the filesystem?
If the average service time per sarr is < 5 ms, Is this a case of bloated
index where re-indexing is warranted?

Thanks

explain (analyze,buffers,timing,verbose,costs)
select count(*) from jim.pitations ;

QUERY PLAN

-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Aggregate (cost=72893810.73..72893810.74 rows=1 width=8) (actual
time=61141110.437..61141110.437 rows=1 loops=1)
Output: count(*)
Buffers: shared hit=72620045 read=45297330
I/O Timings: read=57489958.088
-> Index Only Scan using pit_indx_fk03 on jim.pitations
(cost=0.58..67227187.37 rows=2266649344 width=0) (actual
time=42.327..60950272.189 rows=2269623575 loops=1)
Output: vsr_number
Heap Fetches: 499950392
Buffers: shared hit=72620045 read=45297330
I/O Timings: read=57489958.088
Planning time: 14.014 ms
Execution time: 61,141,110.516 ms
(11 rows)
Time: 61141132.309 ms
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Sun 16.09.2018 14:52
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