Re: Reduce timing overhead of EXPLAIN ANALYZE using rdtsc?

Hi,

It looks like this recent failure on buildfarm member drongo might be
related to the timing changes - mainly suspecting it because the
commits are in the (slightly larger) set that changed, and the error
is in a timing related module that uses INSTR_TIME_SET_CURRENT.

From https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=drongo&dt=2026-04-08%2001%3A57%3A00

# diff --strip-trailing-cr -U3
C:/prog/bf/root/HEAD/pgsql/contrib/tsm_system_time/expected/tsm_system_time.out
C:/prog/bf/root/HEAD/pgsql.build/testrun/tsm_system_time/regress/results/tsm_system_time.out
# --- C:/prog/bf/root/HEAD/pgsql/contrib/tsm_system_time/expected/tsm_system_time.out
2023-01-23 04:39:00.533642000 +0000
# +++ C:/prog/bf/root/HEAD/pgsql.build/testrun/tsm_system_time/regress/results/tsm_system_time.out
2026-04-08 04:03:15.248127800 +0000
# @@ -15,7 +15,7 @@
# SELECT count(*) FROM test_tablesample TABLESAMPLE system_time (100000);
# count
# -------
# - 31
# + 16
# (1 row)
#
# -- bad parameters should get through planning, but not execution:
# 1 of 1 tests failed.
# The differences that caused some tests to fail can be viewed in the
file "C:/prog/bf/root/HEAD/pgsql.build/testrun/tsm_system_time/regress/regression.diffs".
# A copy of the test summary that you see above is saved in the file
"C:/prog/bf/root/HEAD/pgsql.build/testrun/tsm_system_time/regress/regression.out".

Haven't had a chance to dig through it yet, just noting it to start.

Thanks,
Lukas

--
Lukas Fittl