Re: Single transaction in the tablesync worker?

Hi Amit.

PSA the v18 patch for the Tablesync Solution1.

Main differences from v17:
+ Design change to use TEMPORARY tablesync slots [ak0122] means lots
of the v17 slot cleanup code became unnecessary.
+ Small refactor in LogicalReplicationSyncTableStart to fix a deadlock scenario.
+ Addressing some review comments [ak0121].

[ak0121] https://www.postgresql.org/message-id/CAA4eK1LGxuB_RTfZ2HLJT76wv%3DFLV6UPqT%2BFWkiDg61rvQkkmQ%40mail.gmail.com
[ak0122] https://www.postgresql.org/message-id/CAA4eK1LS0_mdVx2zG3cS%2BH88FJiwyS3kZi7zxijJ_gEuw2uQ2g%40mail.gmail.com

====

Features:

* The tablesync slot name is no longer tied to the Subscription slot name.

* The tablesync worker is now allowing multiple tx instead of single tx

* A new state (SUBREL_STATE_FINISHEDCOPY) is persisted after a
successful copy_table in tablesync's LogicalRepSyncTableStart.

* If a re-launched tablesync finds state SUBREL_STATE_FINISHEDCOPY
then it will bypass the initial copy_table phase.

* Now tablesync sets up replication origin tracking in
LogicalRepSyncTableStart (similar as done for the apply worker). The
origin is advanced when first created.

* The tablesync replication origin tracking record is cleaned up by:
- process_syncing_tables_for_apply
- DropSubscription
- AlterSubscription_refresh

* Updates to PG docs.

* New TAP test case

Known Issues:

* None.

---
Kind Regards,
Peter Smith.
Fujitsu Australia