Horton

Re: Skipping logical replication transactions on subscriber side

Greg Nancarrow <gregn4422@gmail.com>

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From: Greg Nancarrow <gregn4422@gmail.com>
To: Masahiko Sawada <sawada.mshk@gmail.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>, "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>, "tanghy.fnst@fujitsu.com" <tanghy.fnst@fujitsu.com>, "osumi.takamichi@fujitsu.com" <osumi.takamichi@fujitsu.com>, Alexey Lesovsky <lesovsky@gmail.com>, Peter Eisentraut <peter.eisentraut@enterprisedb.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2021-10-08T11:17:38Z
Lists: pgsql-hackers 
On Thu, Sep 30, 2021 at 3:45 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
>
> I've attached updated patches that incorporate all comments I got so
> far. Please review them.
>

Some comments about the v15-0001 patch:

(1) patch adds a whitespace error

Applying: Add a subscription errors statistics view
"pg_stat_subscription_errors".
.git/rebase-apply/patch:1656: new blank line at EOF.
+
warning: 1 line adds whitespace errors.

(2) Patch comment says "This commit adds a new system view
pg_stat_logical_replication_errors ..."
BUT this is the wrong name, it should be "pg_stat_subscription_errors".


doc/src/sgml/monitoring.sgml

(3)
"Message of the error" doesn't sound right. I suggest just saying "The
error message".

(4) view column "last_failed_time"
I think it would be better to name this "last_error_time".


src/backend/postmaster/pgstat.c

(5) pgstat_vacuum_subworker_stats()

Spelling mistake in the following comment:

/* Create a map for mapping subscriptoin OID and database OID */

subscriptoin -> subscription

(6)
In the following functions:

pgstat_read_statsfiles
pgstat_read_db_statsfile_timestamp

The following comment should say "... struct describing subscription
worker statistics."
(i.e. need to remove the "a")

+ * 'S' A PgStat_StatSubWorkerEntry struct describing a
+ * subscription worker statistics.


(7) pgstat_get_subworker_entry

Suggest comment change:

BEFORE:
+ * Return the entry of subscription worker entry with the subscription
AFTER:
+ * Return subscription worker entry with the given subscription

(8) pgstat_recv_subworker_error

+ /*
+ * Update only the counter and timestamp if we received the same error
+ * again
+ */
+ if (wentry->relid == msg->m_relid &&
+ wentry->command == msg->m_command &&
+ wentry->xid == msg->m_xid &&
+ strncmp(wentry->message, msg->m_message, strlen(wentry->message)) == 0)
+ {

Is there a reason that the above check uses strncmp() with
strlen(wentry->message), instead of just strcmp()?
msg->m_message is treated as the same error message if it is the same
up to strlen(wentry->message)?
Perhaps if that is intentional, then the comment should be updated.

src/tools/pgindent/typedefs.list

(9)
The added "PgStat_SubWorkerError" should be removed from the
typedefs.list (as there is no such new typedef).


Regards,
Greg Nancarrow
Fujitsu Australia

Commits

  1. Test ALIGNOF_DOUBLE==4 compatibility under ALIGNOF_DOUBLE==8.

  2. Reorder subskiplsn in pg_subscription to avoid alignment issues.

  3. Add ALTER SUBSCRIPTION ... SKIP.

  4. Optionally disable subscriptions on error.

  5. Update docs of logical replication for commit 8d74fc96db.

  6. Respect permissions within logical replication.

  7. Fix regression test failure caused by commit 8d74fc96db.

  8. Add a view to show the stats of subscription workers.

  9. Add logical change details to logical replication worker errcontext.

  10. Rename LOGICAL_REP_MSG_STREAM_END to LOGICAL_REP_MSG_STREAM_STOP.

  11. Fix typo in protocol.sgml.

  12. Remove unused argument in apply_handle_commit_internal().

  13. Fix replication of in-progress transactions in tablesync worker.

  14. Reorder pg_sequence columns to avoid alignment issue