Hi Sehrope, Thank you for the detailed review!
On Sat, Sep 5, 2026, Sehrope Sarkuni wrote: > I think this needs an opt-in from the client. Something like a > START_REPLICATION option or at least a protocol guard. I agree. v2 adds a SKIP_WAL_PADDING option to physical START_REPLICATION. Existing clients continue to receive ordinary WALData messages, and built-in clients request the new format only from PG20 servers. The receiver no longer truncates and extends the segment. A segment newly created by walreceiver is already zero-filled according to wal_init_zero. For an existing or recycled segment, walreceiver writes the zeros locally with the normal wait-event and pg_stat_io accounting. This also removes the short-file crash window. New uncompressed pg_receivewal output is already pre-padded. Resumed, compressed, and tar output generate the zeros locally. I also added the missing Meson registration and used pg_memory_is_all_zeros(). As a compatibility check, I connected a pre-patch PG20 pg_receivewal to the patched server and compared the resulting switched segment byte for byte. PFA v2. Thank you! Best regards, Andrey Borodin.
v2-0001-Avoid-streaming-zero-filled-WAL-switch-padding.patch
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