bk commit into 5.0 tree (holyfoot:1.2490) BUG#27984

[holyfoot]

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5.0 repository of hf. When hf does a push these changes will
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ChangeSet@stripped, 2007-05-20 00:34:53+05:00, holyfoot@stripped +3 -0
  Bug #27984 Long Decimal Maths produces truncated results
  decimal_round failed to round the number starting
  with nine 9-s, setting first nine digits of the decimal to zero.

  mysql-test/r/type_newdecimal.result@stripped, 2007-05-20 00:34:51+05:00, holyfoot@stripped
+3 -0
    Bug #27984 Long Decimal Maths produces truncated results
    test result

  mysql-test/t/type_newdecimal.test@stripped, 2007-05-20 00:34:51+05:00, holyfoot@stripped +5
-0
    Bug #27984 Long Decimal Maths produces truncated results
    test case

  strings/decimal.c@stripped, 2007-05-20 00:34:51+05:00, holyfoot@stripped +2 -1
    Bug #27984 Long Decimal Maths produces truncated results
    when to == from we break the data if we do to->buf[0]=0
    So now doing this after the data is moved back and only
    if we need to set to->buf[0] to zero

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	holyfoot
# Host:	hfmain.(none)
# Root:	/home/hf/work/27984/my50-27984

--- 1.46/mysql-test/r/type_newdecimal.result	2007-05-20 00:34:57 +05:00
+++ 1.47/mysql-test/r/type_newdecimal.result	2007-05-20 00:34:57 +05:00
@@ -1465,4 +1465,7 @@ Error	1264	Out of range value adjusted f
 Error	1264	Out of range value adjusted for column 'cast(a as DECIMAL(3,2))' at row 1
 Error	1264	Out of range value adjusted for column 'cast(a as DECIMAL(3,2))' at row 1
 Error	1264	Out of range value adjusted for column 'cast(a as DECIMAL(3,2))' at row 1
+SELECT 99.999999999998 / 100;
+99.999999999998 / 100
+0.9999999999999800
 End of 5.0 tests

--- 1.44/mysql-test/t/type_newdecimal.test	2007-05-20 00:34:57 +05:00
+++ 1.45/mysql-test/t/type_newdecimal.test	2007-05-20 00:34:57 +05:00
@@ -1149,4 +1149,9 @@ select cast(a as DECIMAL(3,2)), count(*)
   UNION select 12.1234
  ) t group by 1;
 
+#
+# Bug #27984 Long Decimal Maths produces truncated results 
+#
+
+SELECT 99.999999999998 / 100;
 --echo End of 5.0 tests

--- 1.79/strings/decimal.c	2007-05-20 00:34:57 +05:00
+++ 1.80/strings/decimal.c	2007-05-20 00:34:57 +05:00
@@ -1517,9 +1517,10 @@ decimal_round(decimal_t *from, decimal_t
     dec1 *p0= buf0+intg0+max(frac1, frac0);
     dec1 *p1= buf1+intg1+max(frac1, frac0);
 
-    to->buf[0]= 0;
     while (buf0 < p0)
       *(--p1) = *(--p0);
+    if (unlikely(intg1 > intg0))
+      to->buf[0]= 0;
 
     intg0= intg1;
     buf0=to->buf;