From 59bb147353ba274e0836d06f429176d4be47452c Mon Sep 17 00:00:00 2001
From: Bruce Momjian <bruce@momjian.us>
Date: Fri, 3 Feb 2006 12:45:47 +0000
Subject: [PATCH] Update random() usage so ranges are inclusive/exclusive as
 required.

---
 src/backend/commands/analyze.c      | 13 +++----------
 src/backend/storage/lmgr/s_lock.c   |  4 ++--
 src/backend/utils/adt/float.c       |  6 +++---
 src/include/optimizer/geqo_random.h |  4 ++--
 4 files changed, 10 insertions(+), 17 deletions(-)

diff --git a/src/backend/commands/analyze.c b/src/backend/commands/analyze.c
index 095ffe783f..06bbe5d324 100644
--- a/src/backend/commands/analyze.c
+++ b/src/backend/commands/analyze.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/analyze.c,v 1.90 2005/11/22 18:17:08 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/analyze.c,v 1.91 2006/02/03 12:45:47 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -927,18 +927,11 @@ acquire_sample_rows(Relation onerel, HeapTuple *rows, int targrows,
 	return numrows;
 }
 
-/* Select a random value R uniformly distributed in 0 < R < 1 */
+/* Select a random value R uniformly distributed in (0 - 1) */
 static double
 random_fract(void)
 {
-	long		z;
-
-	/* random() can produce endpoint values, try again if so */
-	do
-	{
-		z = random();
-	} while (z <= 0 || z >= MAX_RANDOM_VALUE);
-	return (double) z / (double) MAX_RANDOM_VALUE;
+	return ((double) random() + 1) / ((double) MAX_RANDOM_VALUE + 2);
 }
 
 /*
diff --git a/src/backend/storage/lmgr/s_lock.c b/src/backend/storage/lmgr/s_lock.c
index e0ffcecc79..774731f2c6 100644
--- a/src/backend/storage/lmgr/s_lock.c
+++ b/src/backend/storage/lmgr/s_lock.c
@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/storage/lmgr/s_lock.c,v 1.41 2005/11/22 18:17:21 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/storage/lmgr/s_lock.c,v 1.42 2006/02/03 12:45:47 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -120,7 +120,7 @@ s_lock(volatile slock_t *lock, const char *file, int line)
 
 			/* increase delay by a random fraction between 1X and 2X */
 			cur_delay += (int) (cur_delay *
-				  (((double) random()) / ((double) MAX_RANDOM_VALUE)) + 0.5);
+				  ((double) random() / (double) MAX_RANDOM_VALUE) + 0.5);
 			/* wrap back to minimum delay when max is exceeded */
 			if (cur_delay > MAX_DELAY_MSEC)
 				cur_delay = MIN_DELAY_MSEC;
diff --git a/src/backend/utils/adt/float.c b/src/backend/utils/adt/float.c
index d50e4eaf6f..488b43461b 100644
--- a/src/backend/utils/adt/float.c
+++ b/src/backend/utils/adt/float.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/float.c,v 1.119 2005/12/02 02:49:11 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/float.c,v 1.120 2006/02/03 12:45:47 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1833,8 +1833,8 @@ drandom(PG_FUNCTION_ARGS)
 {
 	float8		result;
 
-	/* result 0.0-1.0 */
-	result = ((double) random()) / ((double) MAX_RANDOM_VALUE);
+	/* result [0.0 - 1.0) */
+	result = (double) random() / ((double) MAX_RANDOM_VALUE + 1);
 
 	PG_RETURN_FLOAT8(result);
 }
diff --git a/src/include/optimizer/geqo_random.h b/src/include/optimizer/geqo_random.h
index 5d97143046..1bc54a60c5 100644
--- a/src/include/optimizer/geqo_random.h
+++ b/src/include/optimizer/geqo_random.h
@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/optimizer/geqo_random.h,v 1.16 2004/12/31 22:03:36 pgsql Exp $
+ * $PostgreSQL: pgsql/src/include/optimizer/geqo_random.h,v 1.17 2006/02/03 12:45:47 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -28,7 +28,7 @@
 
 /* geqo_rand returns a random float value between 0 and 1 inclusive */
 
-#define geqo_rand() (((double) random()) / ((double) MAX_RANDOM_VALUE))
+#define geqo_rand() ((double) random() / (double) MAX_RANDOM_VALUE)
 
 /* geqo_randint returns integer value between lower and upper inclusive */
 
-- 
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