Horton

Re: Skipping logical replication transactions on subscriber side

Peter Eisentraut <peter.eisentraut@enterprisedb.com>

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From: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: Masahiko Sawada <sawada.mshk@gmail.com>, "tanghy.fnst@fujitsu.com" <tanghy.fnst@fujitsu.com>, vignesh C <vignesh21@gmail.com>, Greg Nancarrow <gregn4422@gmail.com>, "houzj.fnst@fujitsu.com" <houzj.fnst@fujitsu.com>, Alexey Lesovsky <lesovsky@gmail.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>, "osumi.takamichi@fujitsu.com" <osumi.takamichi@fujitsu.com>
Date: 2022-01-25T12:48:38Z
Lists: pgsql-hackers 
On 25.01.22 03:54, Amit Kapila wrote:
>> I don't think this functionality allows a nonprivileged user to do
>> anything they couldn't otherwise do.  You can create inconsistent data
>> in the sense that you can choose not to apply certain replicated data.
>>
> I thought this will be the only primary way to skip applying certain
> transactions. The other could be via pg_replication_origin_advance().
> Or are you talking about the case where we skip applying update/delete
> where the corresponding rows are not found?
> 
> I see the point that if we can allow the owner to skip applying
> updates/deletes in certain cases then probably this should also be
> okay. Kindly let us know if you have something else in mind as well?

Let's start this again: The question at hand is whether ALTER 
SUBSCRIPTION ... SKIP should be allowed for subscription owners that are 
not superusers.  The argument raised against that was that this would 
allow the owner to create "inconsistent" data.  But it hasn't been 
explained what that actually means or why it is dangerous.

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