Horton

RE: Skipping logical replication transactions on subscriber side

tanghy.fnst@fujitsu.com <tanghy.fnst@fujitsu.com>

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From: "tanghy.fnst@fujitsu.com" <tanghy.fnst@fujitsu.com>
To: Masahiko Sawada <sawada.mshk@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>
Cc: Greg Nancarrow <gregn4422@gmail.com>, vignesh C <vignesh21@gmail.com>, Peter Eisentraut <peter.eisentraut@enterprisedb.com>, "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>, "osumi.takamichi@fujitsu.com" <osumi.takamichi@fujitsu.com>, Alexey Lesovsky <lesovsky@gmail.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2022-01-13T01:07:49Z
Lists: pgsql-hackers 
On Wed, Jan 12, 2022 2:02 PM Masahiko Sawada <sawada.mshk@gmail.com> wrote:
> 
> I've attached an updated patch that incorporated all comments I got so far.
> 

Thanks for updating the patch. Here are some comments:

1)
+      Skip applying changes of the particular transaction.  If incoming data

Should "Skip" be "Skips" ?

2)
+      prepared by enabling <literal>two_phase</literal> on susbscriber.  After h
+      the logical replication successfully skips the transaction, the transaction

The "h" after word "After" seems redundant.

3)
+   Skipping the whole transaction includes skipping the cahnge that may not violate

"cahnge" should be "changes" I think.

4)
+/*
+ * True if we are skipping all data modification changes (INSERT, UPDATE, etc.) of
+ * the specified transaction at MySubscription->skipxid.  Once we start skipping
...
+ */
+static TransactionId skipping_xid = InvalidTransactionId;
+#define is_skipping_changes() (TransactionIdIsValid(skipping_xid))

Maybe we should modify this comment. Something like:
skipping_xid is valid if we are skipping all data modification changes ...

5)
+					if (!superuser())
+						ereport(ERROR,
+								(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+								 errmsg("must be superuser to set %s", "skip_xid")));

Should we change the message to "must be superuser to skip xid"?
Because the SQL stmt is "ALTER SUBSCRIPTION ... SKIP (xid = XXX)".

Regards,
Tang

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