Thread

Missing empty transaction optimization in pgoutput plugin

Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> — 2025-12-08T06:48:55Z

Hi All,
test_decoding output plugin skips sending stream_start and stream_end
if no change from a segment of a streamed transaction is sent
downstream. If no change has been sent downstream across all the
streamed segments it doesn't send commit or abort for that streamed
transaction. But I don't see similar changes in stream related
callbacks in pgoutput output plugin.

While the changes discussed in thread [1] were committed, those didn't
include this optimization for test_decoding plugin as well. The
optimization was discussed in [2] separately as a bug fix. Maybe
because it wasn't considered as an optimization that time, we may not
have considered it for pgoutput plugin which doesn't have explicit
skip-empty-xacts option. I think the optimization would be useful in
setups where multiple publications and long transactions are common.
Any reason not to have it.

[1] https://www.postgresql.org/message-id/flat/688b0b7f-2f6c-d827-c27b-216a8e3ea700%402ndquadrant.com
[2] https://www.postgresql.org/message-id/flat/CAA4eK1%2BOqgFNZkf7%3DETe_y5ntjgDk3T0wcdkd4Sot_u1hySGfw%40mail.gmail.com
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Best Wishes,
Ashutosh Bapat