From 5af449e98660a42d59347ec4119dec84ffb99f7e Mon Sep 17 00:00:00 2001
From: tgl <tgl>
Date: Mon, 6 Jul 2009 20:29:23 +0000
Subject: [PATCH] Use floor() not rint() when reducing precision of fractional
 seconds in timestamp_trunc, timestamptz_trunc, and interval_trunc().  This
 change only affects the float-datetime case; the integer-datetime case
 already behaved like truncation instead of rounding.  Per gripe from Mario
 Splivalo.

This is a pre-existing issue but I'm choosing not to backpatch, because
it's such a corner case and there have not been prior complaints.  The
issue is largely moot anyway given the trend towards integer datetimes.
---
 src/backend/utils/adt/timestamp.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/backend/utils/adt/timestamp.c b/src/backend/utils/adt/timestamp.c
index a0bf47c264..e00f729e6f 100644
--- a/src/backend/utils/adt/timestamp.c
+++ b/src/backend/utils/adt/timestamp.c
@@ -3338,13 +3338,13 @@ timestamp_trunc(PG_FUNCTION_ARGS)
 #ifdef HAVE_INT64_TIMESTAMP
 				fsec = (fsec / 1000) * 1000;
 #else
-				fsec = rint(fsec * 1000) / 1000;
+				fsec = floor(fsec * 1000) / 1000;
 #endif
 				break;
 
 			case DTK_MICROSEC:
 #ifndef HAVE_INT64_TIMESTAMP
-				fsec = rint(fsec * 1000000) / 1000000;
+				fsec = floor(fsec * 1000000) / 1000000;
 #endif
 				break;
 
@@ -3494,12 +3494,12 @@ timestamptz_trunc(PG_FUNCTION_ARGS)
 #ifdef HAVE_INT64_TIMESTAMP
 				fsec = (fsec / 1000) * 1000;
 #else
-				fsec = rint(fsec * 1000) / 1000;
+				fsec = floor(fsec * 1000) / 1000;
 #endif
 				break;
 			case DTK_MICROSEC:
 #ifndef HAVE_INT64_TIMESTAMP
-				fsec = rint(fsec * 1000000) / 1000000;
+				fsec = floor(fsec * 1000000) / 1000000;
 #endif
 				break;
 
@@ -3591,12 +3591,12 @@ interval_trunc(PG_FUNCTION_ARGS)
 #ifdef HAVE_INT64_TIMESTAMP
 					fsec = (fsec / 1000) * 1000;
 #else
-					fsec = rint(fsec * 1000) / 1000;
+					fsec = floor(fsec * 1000) / 1000;
 #endif
 					break;
 				case DTK_MICROSEC:
 #ifndef HAVE_INT64_TIMESTAMP
-					fsec = rint(fsec * 1000000) / 1000000;
+					fsec = floor(fsec * 1000000) / 1000000;
 #endif
 					break;
 
-- 
2.11.4.GIT