On Monday, July 28, 2025, Daniel Bauman <danielban...@gmail.com> wrote:
> The doc fragment you shared is explaining to customers that basic syntax > checks are done before postgres gets to logging the transaction. > I don't think that is the same as clearly explaining to users statement > logging happens before execution. > He quoted the wrong sentence. This is the definitive one: For clients using extended query protocol, logging occurs when an Execute message is received, and values of the Bind parameters are included (with any embedded single-quote marks doubled). David J. > At least for me, as a user and reader of the docs but not someone familiar > with the code, the docs didn't make it clear to me how statement logging > corresponded to query execution. > > Do you think there's room to document something like > "Statements are logged before they are executed. It's not guaranteed that > logged statements have been successfully executed." > I'd be happy to submit and iterate on a pull request if you do. > The first sentence maybe. If you find this important enough to submit a patch using our submission process go ahead. On that note, please observe that we in-line reply and trim here, not top-post. > > I'd also like to understand what happens if there are errors writing the > log - like the disk where the log directory is configured being full. > My understanding is the following. ereport (https://github.com/postgres/ > postgres/blob/71c0921b649d7a800eb2d6f93539890eaa14d979/src/include/utils/ > elog.h#L163) will end up calling errfinish and errfinish will call > EmitErrorReport (https://github.com/postgres/postgres/blob/master/src/ > backend/utils/error/elog.c#L543) which will call > send_message_to_server_log (https://github.com/postgres/postgres/blob/ > 71c0921b649d7a800eb2d6f93539890eaa14d979/src/backend/utils/ > error/elog.c#L1733) and that will call write_syslogger_file ( > https://github.com/postgres/postgres/blob/71c0921b649d7a800eb2d6f9353989 > 0eaa14d979/src/backend/utils/error/elog.c#L3443C2-L3443C16). > write_syslogger_file looks like it handles errors by logging to stderr but > not raising an error condition that would cancel the transaction ( > https://github.com/postgres/postgres/blob/71c0921b649d7a800eb2d6f9353989 > 0eaa14d979/src/backend/postmaster/syslogger.c#L1126) > > Do I understand correctly or am I on the wrong codepath? > That sounds right. It’s deemed overly harsh to crash the server just because some logging doesn’t happen. David J.
