Re: Single transaction in the tablesync worker?

Hi Amit.

PSA the v20 patch for the Tablesync Solution1.

Main differences from v19:
+ Updated TAP test [ak0123-7]
+ Fixed comment [ak0125-1]
+ Removed redundant header [ak0125-2]
+ Protection against race condition [ak0125-race]

[ak0123-7] https://www.postgresql.org/message-id/CAA4eK1JhpuwujrV6ABMmZ3jXfW37ssZnJ3fikrY7rRdvoEmu_g%40mail.gmail.com
[ak0125-1] https://www.postgresql.org/message-id/CAA4eK1JmP2VVpH2%3DO%3D5BBbuH7gyQtWn40aXp_Jyjn1%2BKggfq8A%40mail.gmail.com
[ak0125-2] https://www.postgresql.org/message-id/CAA4eK1L1j5sfBgHb0-H-%2B2quBstsA3hMcDfP-4vLuU-UF43nXQ%40mail.gmail.com
[ak0125-race] https://www.postgresql.org/message-id/CAA4eK1%2ByeLwBCkTvTdPM-hSk1fr6jT8KJc362CN8zrGztq_JqQ%40mail.gmail.com

====

Features:

* 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:

* Some records arriving between FINISHEDCOPY and SYNCDONE state may be
lost (currently under investigation).

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Kind Regards,
Peter Smith.
Fujitsu Australia