On Tue, Mar 1, 2022 at 8:31 PM Masahiko Sawada <sawada.m...@gmail.com> wrote: > > I’ve considered a plan for the skipping logical replication > transaction feature toward PG15. Several ideas and patches have been > proposed here and another related thread[1][2] for the skipping > logical replication transaction feature as follows: > > A. Change pg_stat_subscription_workers (committed 7a8507329085) > B. Add origin name and commit-LSN to logical replication worker > errcontext (proposed[2]) > C. Store error information (e.g., the error message and commit-LSN) to > the system catalog > D. Introduce ALTER SUBSCRIPTION SKIP > E. Record the skipped data somewhere: server logs or a table > > Given the remaining time for PG15, it’s unlikely to complete all of > them for PG15 by the feature freeze. The most realistic plan for PG15 > in my mind is to complete B and D. With these two items, the LSN of > the error-ed transaction is shown in the server log, and we can ask > users to check server logs for the LSN and use it with ALTER > SUBSCRIPTION SKIP command. >
It makes sense to me to try to finish B and D from the above list for PG-15. I can review the patch for D in detail if others don't have an objection to it. Peter E., others, any opinion on this matter? > If the community agrees with B+D, we will > have a user-visible feature for PG15 which can be further > extended/improved in PG16 by adding C and E. Agreed. > > I've attached an updated patch for D and here is the summary: > > * Introduce a new command ALTER SUBSCRIPTION ... SKIP (lsn = > '0/1234'). The user can get the commit-LSN of the transaction in > question from the server logs thanks to B[2]. > * The user-specified LSN (say skip-LSN) is stored in the > pg_subscription catalog. > * The apply worker skips the whole transaction if the transaction's > commit-LSN exactly matches to skip-LSN. > * The skip-LSN has an effect on only the first non-empty transaction > since the worker started to apply changes. IOW it's cleared after > either skipping the whole transaction or successfully committing a > non-empty transaction, preventing the skip-LSN to remain in the > catalog. Also, since the latter case means that the user set the wrong > skip-LSN we clear it with a warning. > As this will be displayed only in server logs and by background apply worker, should it be LOG or WARNING? -- With Regards, Amit Kapila.
