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Re: Pgoutput not capturing the generated columns

Peter Smith <smithpb2250@gmail.com>

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From: Peter Smith <smithpb2250@gmail.com>
To: Shubham Khanna <khannashubham1197@gmail.com>
Cc: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>, Shlok Kyal <shlok.kyal.oss@gmail.com>, vignesh C <vignesh21@gmail.com>, Rajendra Kumar Dangwal <dangwalrajendra888@gmail.com>, "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>, "euler@eulerto.com" <euler@eulerto.com>
Date: 2024-07-15T05:39:01Z
Lists: pgsql-hackers 
Hi, I had a quick look at the patch v17-0004 which is the split-off
new BMS logic.

IIUC this 0004 is currently undergoing some refactoring and
cleaning-up, so I won't comment much about it except to give the
following observation below.

======
src/backend/replication/logical/proto.c.

I did not expect to see any code fragments that are still checking
generated columns like below:

logicalrep_write_tuple:

  if (att->attgenerated)
  {
- if (!include_generated_columns)
- continue;

  if (att->attgenerated != ATTRIBUTE_GENERATED_STORED)
  continue;
~

  if (att->attgenerated)
  {
- if (!include_generated_columns)
- continue;

  if (att->attgenerated != ATTRIBUTE_GENERATED_STORED)
  continue;

~~~

logicalrep_write_attrs:

  if (att->attgenerated)
  {
- if (!include_generated_columns)
- continue;

  if (att->attgenerated != ATTRIBUTE_GENERATED_STORED)
  continue;

~
if (att->attgenerated)
  {
- if (!include_generated_columns)
- continue;

  if (att->attgenerated != ATTRIBUTE_GENERATED_STORED)
  continue;
~~~


AFAIK, now checking support of generated columns will be done when the
BMS 'columns' is assigned, so the continuation code will be handled
like this:

if (!column_in_column_list(att->attnum, columns))
  continue;

======

BTW there is a subtle but significant difference in this 0004 patch.
IOW, we are introducing a difference between the list of published
columns VERSUS a publication column list. So please make sure that all
code comments are adjusted appropriately so they are not misleading by
calling these "column lists" still.

BEFORE: BMS 'columns'  means "columns of the column list" or NULL if
there was no publication column list
AFTER: BMS 'columns' means "columns to be replicated" or NULL if all
columns are to be replicated

======
Kind Regards,
Peter Smith.

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Doc: Generated column replication.

  2. Rename pubgencols_type to pubgencols in pg_publication.

  3. Doc: Fix column name in pg_publication catalog.

  4. Fix buildfarm failure introduced by commit e65dbc9927.

  5. Change publication's publish_generated_columns option type to enum.

  6. Fix \dRp+ output when describing publications with a lower server version.

  7. Replicate generated columns when 'publish_generated_columns' is set.

  8. Doc: Update the behavior of generated columns in Logical Replication.

  9. Replicate generated columns when specified in the column list.

  10. Doc: Generated columns are skipped for logical replication.