Horton

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

jian he <jian.universality@gmail.com>

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From: jian he <jian.universality@gmail.com>
To: Sutou Kouhei <kou@clear-code.com>
Cc: sawada.mshk@gmail.com, david.g.johnston@gmail.com, tgl@sss.pgh.pa.us, zhjwpku@gmail.com, michael@paquier.xyz, pgsql-hackers@postgresql.org
Date: 2025-04-06T11:29:46Z
Lists: pgsql-hackers 
On Thu, Mar 27, 2025 at 11:29 AM Sutou Kouhei <kou@clear-code.com> wrote:
> We can merge 0001 quickly, right?

I did a brief review of v39-0001 and v39-0002.

text:
COPY_FILE
COPY_FRONTEND
still appear on comments in copyfrom_internal.h and copyto.c,
Should it be removed?


+#include "commands/copyto_internal.h"
#include "commands/progress.h"
#include "executor/execdesc.h"
#include "executor/executor.h"
#include "executor/tuptable.h"

"copyto_internal.h" already include:

#include "executor/execdesc.h"
#include "executor/tuptable.h"
so you should removed
"
#include "executor/execdesc.h"
#include "executor/tuptable.h"
"
in copyto.c.



CREATE FUNCTION test_copy_format(internal)
    RETURNS copy_handler
    AS 'MODULE_PATHNAME', 'test_copy_format'
    LANGUAGE C;
src/backend/commands/copy.c: ProcessCopyOptions
            if (strcmp(fmt, "text") == 0)
                 /* default format */ ;
            else if (strcmp(fmt, "csv") == 0)
                opts_out->csv_mode = true;
            else if (strcmp(fmt, "binary") == 0)
                opts_out->binary = true;
            else
            {
                List       *qualified_format;
                ....
            }
what if our customized format name is one of "csv", "binary", "text",
then that ELSE branch will never be reached.
then our customized format is being shadowed?


https://www.postgresql.org/docs/current/error-message-reporting.html
"The extra parentheses were required before PostgreSQL version 12, but
are now optional."

means that
    ereport(NOTICE, (errmsg("CopyFromInFunc: attribute: %s",
format_type_be(atttypid))));
can change to
    ereport(NOTICE, errmsg("CopyFromInFunc: attribute: %s",
format_type_be(atttypid)));

all
ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE), ....

can also be simplified to

ereport(ERROR, errcode(ERRCODE_INVALID_PARAMETER_VALUE), ....

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.