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| author | Amit Kapila <akapila@postgresql.org> | 2025-02-25 09:22:16 +0530 |
|---|---|---|
| committer | Amit Kapila <akapila@postgresql.org> | 2025-02-25 09:22:16 +0530 |
| commit | 7c906c5b46f8189a04e67bc550cba33dd3851b6e (patch) | |
| tree | acd38764fdf6a43a1ee9dbe39449d452c74e253f /src | |
| parent | 174952ece1c04b725a2eafabf08d7192b99866ca (diff) | |
Doc: Fix pg_copy_logical_replication_slot description.
This commit documents that the failover option is not copied when using
the pg_copy_logical_replication_slot function.
In passing, we modify the comments in the function clarifying the reason
for this behavior.
Reported-by: <duffieldzane@gmail.com>
Author: Hou Zhijie <houzj.fnst@fujitsu.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Backpatch-through: 17, where it was introduced
Discussion: https://postgr.es/m/173976850802.682632.11315364077431550250@wrigleys.postgresql.org
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/replication/slotfuncs.c | 19 |
1 files changed, 12 insertions, 7 deletions
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c index dd6c1d5a7e3..43c3cc7336b 100644 --- a/src/backend/replication/slotfuncs.c +++ b/src/backend/replication/slotfuncs.c @@ -698,13 +698,18 @@ copy_replication_slot(FunctionCallInfo fcinfo, bool logical_slot) * hence pass find_startpoint false. confirmed_flush will be set * below, by copying from the source slot. * - * To avoid potential issues with the slot synchronization where the - * restart_lsn of a replication slot can go backward, we set the - * failover option to false here. This situation occurs when a slot - * on the primary server is dropped and immediately replaced with a - * new slot of the same name, created by copying from another existing - * slot. However, the slot synchronization will only observe the - * restart_lsn of the same slot going backward. + * We don't copy the failover option to prevent potential issues with + * slot synchronization. For instance, if a slot was synchronized to + * the standby, then dropped on the primary, and immediately recreated + * by copying from another existing slot with much earlier restart_lsn + * and confirmed_flush_lsn, the slot synchronization would only + * observe the LSN of the same slot moving backward. As slot + * synchronization does not copy the restart_lsn and + * confirmed_flush_lsn backward (see update_local_synced_slot() for + * details), if a failover happens before the primary's slot catches + * up, logical replication cannot continue using the synchronized slot + * on the promoted standby because the slot retains the restart_lsn + * and confirmed_flush_lsn that are much later than expected. */ create_logical_replication_slot(NameStr(*dst_name), plugin, |