Horton

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

Andrew Dunstan <andrew@dunslane.net>

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From: Andrew Dunstan <andrew@dunslane.net>
To: Michael Paquier <michael@paquier.xyz>, Sutou Kouhei <kou@clear-code.com>
Cc: sawada.mshk@gmail.com, zhjwpku@gmail.com, nathandbossart@gmail.com, pgsql-hackers@postgresql.org
Date: 2024-01-24T12:15:55Z
Lists: pgsql-hackers 
On 2024-01-24 We 03:11, Michael Paquier wrote:
> On Wed, Jan 24, 2024 at 02:49:36PM +0900, Sutou Kouhei wrote:
>> For COPY TO:
>>
>> 0001: This adds CopyToRoutine and use it for text/csv/binary
>> formats. No implementation change. This just move codes.
> 10M without this change:
>
>      format,elapsed time (ms)
>      text,1090.763
>      csv,1136.103
>      binary,1137.141
>
> 10M with this change:
>
>      format,elapsed time (ms)
>      text,1082.654
>      csv,1196.991
>      binary,1069.697
>
> These numbers point out that binary is faster by 6%, csv is slower by
> 5%, while text stays around what looks like noise range.  That's not
> negligible.  Are these numbers reproducible?  If they are, that could
> be a problem for anybody doing bulk-loading of large data sets.  I am
> not sure to understand where the improvement for binary comes from by
> reading the patch, but perhaps perf would tell more for each format?
> The loss with csv could be blamed on the extra manipulations of the
> function pointers, likely.


I don't think that's at all acceptable.

We've spent quite a lot of blood sweat and tears over the years to make 
COPY fast, and we should not sacrifice any of that lightly.


cheers


andrew

--
Andrew Dunstan
EDB: https://www.enterprisedb.com

Commits

  1. Refactor Copy{From|To}GetRoutine() to use pass-by-reference argument.

  2. Refactor COPY FROM to use format callback functions.

  3. Refactor COPY TO to use format callback functions.

  4. Another try to fix BF failure introduced in commit ddd5f4f54a.

  5. Revert "Refactor CopyReadAttributes{CSV,Text}() to use a callback in COPY FROM"

  6. Improve COPY TO performance when server and client encodings match

  7. Simplify signature of CopyAttributeOutCSV() in copyto.c

  8. Revert "Refactor CopyAttributeOut{CSV,Text}() to use a callback in COPY TO"

  9. Refactor CopyAttributeOut{CSV,Text}() to use a callback in COPY TO

  10. Refactor CopyReadAttributes{CSV,Text}() to use a callback in COPY FROM

  11. Add progress reporting of skipped tuples during COPY FROM.

  12. pgbench: Add \syncpipeline

  13. meson: Make gzip and tar optional

  14. Export the external file reader used in COPY FROM as APIs.