Re: Make COPY format extendable: Extract COPY TO format implementations

Hi,

In <20240222(dot)183948(dot)518018047578925034(dot)kou(at)clear-code(dot)com>
"Re: Make COPY format extendable: Extract COPY TO format implementations" on Thu, 22 Feb 2024 18:39:48 +0900 (JST),
Sutou Kouhei <kou(at)clear-code(dot)com> wrote:

> How about adding "is_csv" to CopyReadline() and
> CopyReadLineText() too?

I tried this on my environment. This is a change for COPY
FROM not COPY TO but this decreases COPY TO
performance with [1]... Hmm...

master: 697.693 msec (the best case)
v15: 576.374 msec (the best case)
v15+this: 593.559 msec (the best case)

[1] COPY (SELECT 1::int2,2::int2,3::int2,4::int2,5::int2,6::int2,7::int2,8::int2,9::int2,10::int2,11::int2,12::int2,13::int2,14::int2,15::int2,16::int2,17::int2,18::int2,19::int2,20::int2, generate_series(1, 1000000::int4)) TO '/dev/null' \watch c=15

So I think that v15 is good.

perf result of master:

# Children Self Command Shared Object Symbol
# ........ ........ ........ ................. .........................................
#
31.39% 14.54% postgres postgres [.] CopyOneRowTo
|--17.00%--CopyOneRowTo
| |--10.61%--FunctionCall1Coll
| | --8.40%--int2out
| | |--2.58%--pg_ltoa
| | | --0.68%--pg_ultoa_n
| | |--1.11%--pg_ultoa_n
| | |--0.83%--AllocSetAlloc
| | |--0.69%--__memcpy_avx_unaligned_erms (inlined)
| | |--0.58%--FunctionCall1Coll
| | --0(dot)55%--memcpy(at)plt
| |--3.25%--appendBinaryStringInfo
| | --0.56%--pg_ultoa_n
| --0.69%--CopyAttributeOutText

perf result of v15:

# Children Self Command Shared Object Symbol
# ........ ........ ........ ................. .........................................
#
25.60% 10.47% postgres postgres [.] CopyToTextOneRow
|--15.39%--CopyToTextOneRow
| |--10.44%--FunctionCall1Coll
| | |--7.25%--int2out
| | | |--2.60%--pg_ltoa
| | | | --0.71%--pg_ultoa_n
| | | |--0.90%--FunctionCall1Coll
| | | |--0.84%--pg_ultoa_n
| | | --0.66%--AllocSetAlloc
| | |--0.79%--ExecProjectSet
| | --0.68%--int4out
| |--2.50%--appendBinaryStringInfo
| --0.53%--CopyAttributeOutText

The profiles on Michael's environment [2] showed that
CopyOneRow() % was increased by v15. But it
(CopyToTextOneRow() % not CopyOneRow() %) wasn't increased
by v15. It's decreased instead.

[2] https://www.postgresql.org/message-id/flat/ZdbtQJ-p5H1_EDwE%40paquier.xyz#6439e6ad574f2d47cd7220e9bfed3889

So I think that v15 doesn't have performance regression but
my environment isn't suitable for benchmark...

Thanks,
--
kou