From: John Naylor <john.naylor@postgresql.org>
Date: Thu, 2 Jul 2026 06:26:56 +0000 (+0700)
Subject: Fix loss of precision in pg_stat_us_to_ms()
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=3eca140531f1c8e58e9a59af827488616699a052;p=thirdparty%2Fpostgresql.git

Fix loss of precision in pg_stat_us_to_ms()

Multiplying by the constant 0.001 can produce trailing-digit noise in
displayed values (for example 0.009000000000000001 instead of 0.009,
with default extra_float_digits) because 0.001 cannot be represented
exactly in binary floating point. Use division by 1000.0 instead,
matching code elsewhere in the tree.

Author: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Discussion: https://postgr.es/m/akIYkMK4bHe9qX/N@bdtpg
---

diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 0c6a20843a5..b5f27b0463c 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -1457,7 +1457,7 @@ pgstat_get_io_time_index(IOOp io_op)
 static inline double
 pg_stat_us_to_ms(PgStat_Counter val_ms)
 {
-	return val_ms * (double) 0.001;
+	return (double) val_ms / 1000.0;
 }
 
 /*