Re: In PG12, query with float calculations is slower than PG11 - Mailing list pgsql-hackers

From Andres Freund
Subject Re: In PG12, query with float calculations is slower than PG11
Date
Msg-id 20200207181329.d6e22ibtnfc5oblh@alap3.anarazel.de
Whole thread Raw
In response to Re: In PG12, query with float calculations is slower than PG11  (Amit Langote <amitlangote09@gmail.com>)
Responses Re: In PG12, query with float calculations is slower than PG11
List pgsql-hackers
Hi,

On 2020-02-07 17:17:21 +0900, Amit Langote wrote:
> I did some tests using two relatively recent compilers: gcc 8 and
> clang-7 and here are the results:

Hm, these very much look like they've been done in an unoptimized build?

>     40.62%  postgres  postgres           [.] ExecInterpExpr
>      9.74%  postgres  postgres           [.] float8_accum
>      6.12%  postgres  libc-2.17.so       [.] __isinf
>      5.96%  postgres  postgres           [.] float8mul
>      5.33%  postgres  postgres           [.] dsqrt
>      3.90%  postgres  postgres           [.] ftod
>      3.53%  postgres  postgres           [.] Float8GetDatum
>      2.34%  postgres  postgres           [.] DatumGetFloat8
>      2.15%  postgres  postgres           [.] AggCheckCallContext
>      2.03%  postgres  postgres           [.] slot_deform_tuple
>      1.95%  postgres  libm-2.17.so       [.] __sqrt
>      1.19%  postgres  postgres           [.] check_float8_array

> HEAD
> 
> latency average = 549.071 ms
> 
>     31.74%  postgres  postgres           [.] ExecInterpExpr
>     11.02%  postgres  libc-2.17.so       [.] __isinf
>     10.58%  postgres  postgres           [.] float8_accum
>      4.84%  postgres  postgres           [.] check_float8_val
>      4.66%  postgres  postgres           [.] dsqrt
>      3.91%  postgres  postgres           [.] float8mul
>      3.56%  postgres  postgres           [.] ftod
>      3.26%  postgres  postgres           [.] Float8GetDatum
>      2.91%  postgres  postgres           [.] float8_mul
>      2.30%  postgres  postgres           [.] DatumGetFloat8
>      2.19%  postgres  postgres           [.] slot_deform_heap_tuple
>      1.81%  postgres  postgres           [.] AggCheckCallContext
>      1.31%  postgres  libm-2.17.so       [.] __sqrt
>      1.25%  postgres  postgres           [.] check_float8_array

Because DatumGetFloat8, Float8GetDatum, etc aren't functions that
normally stay separate.

Greetings,

Andres Freund



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