Re: Improve error reporting in 027_stream_regress test

On Wed, Dec 03, 2025 at 11:01:31PM -0800, Brandon Tat wrote:
> Regarding the function regression_log_helper(), this function reads
> all the lines in the logs at line 219 of
> src/test/recovery/t/027_stream_regress.pl. It seems wasteful to read
> the file again twice in read_file_ends(). Alternatively, we could
> read the file once within regression_log_helper() and index lines to
> emit the lines that we want. 

It seems to me that you are looking at v4-0001 and v4-0002 posted at
[1], which I did not author.  So your suggestion would be to call
read_file_ends() once with the file opened once, with three modes
instead of the two presented in the patch: fetch the head, the tail,
or both at the same time.  Yes, that would be more efficient.

While looking at the patch with fresher eyes (didn't look at this
thread for a couple of months, sorry), it looks like there is no point
in having regression_log_helper() at all.  We could just return the
tail and the head in a single call of read_file_ends() with two output
variables.  Then we could embed in read_file_ends() the knowledge that
if we are dealing with a file that has less lines than twice
PG_TEST_FILE_READ_LINES, we can just print the whole file, returning
only the full contents as in a variable for what would have been the
head content, leaving the tail content empty.

If somebody would like to send a patch among these lines, feel free..

[1]: https://www.postgresql.org/message-id/CAN55FZ09GfUAg5X5CFDgSA0K-u3W8e2HoWHW7CdMFdo_7Fa-Ug@mail.gmail.com
--
Michael