Re: pg_stat_replication write_lsn documentation ambiguity?

[Rui DeSousa <rui@xxxxxxxxxxxxx>]

On Mar 26, 2025, at 12:35 PM, Ron Johnson <ronljohnsonjr@xxxxxxxxx> wrote:

https://www.postgresql.org/docs/14/monitoring-stats.html#MONITORING-PG-STAT-REPLICATION-VIEW

write_lsn pg_lsn

Last write-ahead log location written to disk by this standby server

flush_lsn pg_lsn

Last write-ahead log location flushed to disk by this standby server

They both say "to disk".  Should the write_lsn description be changed to "to the OS"?

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It is understandable to me, especially in the context of write vs flush. Maybe to ‘to the WAL file” if ‘to disk’ is not clear. 

From write() man page:

The write() system call attempts to write nbytes of data to the object

     referenced by the descriptor fd

From sync() man page:

The sync() system call forces a write of dirty (modified) buffers in the

     block buffer cache out to disk.