MySQL Bugs: #26469: Falcon: searches fail if decimal(6,6) column and index exists

Bug #26469	Falcon: searches fail if decimal(6,6) column and index exists
Submitted:	18 Feb 2007 0:49	Modified:	20 Apr 2007 14:45
Reporter:	Peter Gulutzan	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: Falcon storage engine	Severity:	S2 (Serious)
Version:	5.2.4-falcon-alpha-debug	OS:	Linux (SUSE 10.0 / 64-bit)
Assigned to:	Jim Starkey	CPU Architecture:	Any

Description:
I create a table with a decimal(6,6) indexed column.
I insert ... 0.000001.
I search for 0.000001.
Nothing is found.

This doesn't happen with a decimal(5,5) column.
This doesn't happen with an unindexed column.

How to repeat:
mysql> create table t27 (s1 decimal(6,6), key(s1)) engine=falcon;
Query OK, 0 rows affected (0.01 sec)

mysql> insert into t27 values      (0.000001);
Query OK, 1 row affected (0.00 sec)

mysql> select * from t27 where s1 = 0.000001;
Empty set (0.00 sec)

Verified as described. Added test case falcon_bug_26469.test and pushed into mysql-5.1-falcon tree.

TEST                           RESULT         TIME (ms)
-------------------------------------------------------

falcon_bug_26469               [ fail ]

Errors are (from /home/hakan/work/mysql/mysql-5.1-falcon/mysql-test/var/log/mysqltest-time) :
mysqltest: Result content mismatch
(the last lines may be the most important ones)
Below are the diffs between actual and expected results:
-------------------------------------------------------
*** r/falcon_bug_26469.result   2007-02-18 05:15:16.000000000 +0300
--- r/falcon_bug_26469.reject   2007-02-18 05:15:19.000000000 +0300
***************
*** 5,9 ****
  INSERT INTO t1 VALUES (0.000001);
  SELECT count(*) FROM t1 WHERE a = 0.000001;
  count(*)
! 1
  DROP TABLE t1;
--- 5,9 ----
  INSERT INTO t1 VALUES (0.000001);
  SELECT count(*) FROM t1 WHERE a = 0.000001;
  count(*)
! 0
  DROP TABLE t1;
-------------------------------------------------------
Please follow the instructions outlined at
http://www.mysql.com/doc/en/Reporting_mysqltest_bugs.html
to find the reason to this problem and how to report this.

Regards, Hakan

BigInt and Value where using different algorithms to scale double
number resulting in a low bit error.  They now use the same code.

Passes now:

TEST                           RESULT         TIME (ms)
-------------------------------------------------------

falcon_bug_26469               [ pass ]            254
-------------------------------------------------------
Stopping All Servers
All 1 tests were successful.
The servers where restarted 1 times
Spent 0.254 seconds actually executing testcases

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/24910

ChangeSet@1.2623, 2007-04-19 19:11:44+02:00, hakank@lu0011.wdf.sap.corp +1 -0
  Test for Bug#26469 passes now.

A note has been added to the 5.2.4 changelog.

This bug report entry has been moved to the 6.0.0 Falcon changelog.