Horton

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

Sutou Kouhei <kou@clear-code.com>

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From: Sutou Kouhei <kou@clear-code.com>
To: sawada.mshk@gmail.com
Cc: michael@paquier.xyz, zhjwpku@gmail.com, andrew@dunslane.net, nathandbossart@gmail.com, pgsql-hackers@postgresql.org
Date: 2024-01-16T02:53:00Z
Lists: pgsql-hackers 
Hi,

In <CAD21AoB5x86TTyer90iSFivnSD8MFRU8V4ALzmQ=rQFw4QqiXQ@mail.gmail.com>
  "Re: Make COPY format extendable: Extract COPY TO format implementations" on Mon, 15 Jan 2024 16:03:41 +0900,
  Masahiko Sawada <sawada.mshk@gmail.com> wrote:

>> Defining one more static const struct instead of providing a
>> convenient (but a bit tricky) macro may be straightforward:
>>
>> static const CopyToFormatRoutine testfmt_copyto_routine = {
>>     .type = T_CopyToFormatRoutine,
>>     .start_fn = testfmt_copyto_start,
>>     .onerow_fn = testfmt_copyto_onerow,
>>     .end_fn = testfmt_copyto_end
>> };
>>
>> static const CopyFormatRoutine testfmt_copyto_handler = {
>>     .type = T_CopyFormatRoutine,
>>     .is_from = false,
>>     .routine = (Node *) &testfmt_copyto_routine
>> };
> 
> Yeah, IIUC this is the option 2 you mentioned[1]. I think we can go
> with this idea as it's the simplest.
>
> [1] https://www.postgresql.org/message-id/20240110.120034.501385498034538233.kou%40clear-code.com

Ah, you're right. I forgot it...

>                  That is CopyFormatRoutine will be like:
> 
> typedef struct CopyFormatRoutine
> {
>     NodeTag     type;
> 
>     /* either CopyToFormatRoutine or CopyFromFormatRoutine */
>     Node       *routine;
> }           CopyFormatRoutine;
> 
> And the core can check the node type of the 'routine7 in the
> CopyFormatRoutine returned by extensions.

It makes sense.


If no more comments about the current design, I'll start
implementing this feature based on the current design.


Thanks,
-- 
kou

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.