Re: bzr commit into mysql-5.1 branch (davi:2667) Bug#21704, Bug#33873

[Vasil Dimov]

On Tue, Jun 17, 2008 at 11:12:30 -0300, Davi Arnaut wrote:
> # At a local mysql-5.1 repository of davi
> 
>  2667 Davi Arnaut	2008-06-17
>       Bug#33873: Fast ALTER TABLE doesn't work with multibyte character sets
>       
>       The problem was that when comparing tables for a possible
>       fast alter table, the comparison was being performed using
>       the parsed information and not the final definition.
>             
>       The solution is to use the possible final table layout to
>       compare if a fast alter is possible or not.
> modified:
>   mysql-test/include/mix1.inc
>   mysql-test/r/alter_table.result
>   mysql-test/r/innodb_mysql.result
>   mysql-test/t/alter_table.test
>   sql/sql_table.cc
[...]

Hi,

This commit introduces the following change in behavior:

--- cut ---
DROP TABLE t1, t2, t3;

CREATE TABLE t1 (a INT, b BLOB, c TEXT, d TEXT NOT NULL)
ENGINE=INNODB DEFAULT CHARSET=UTF8;

CREATE TABLE t2 (d VARCHAR(17) PRIMARY KEY) ENGINE=INNODB DEFAULT CHARSET=UTF8;

CREATE TABLE t3 (a INT PRIMARY KEY) ENGINE=INNODB;

INSERT INTO t2 VALUES ('jejdkrun87'), ('adfdijn0loKNHJik');

INSERT INTO t3 VALUES (22), (44), (66);

INSERT INTO t1 SELECT
a, LEFT(REPEAT(d, 100), 65535), REPEAT(d,100), d FROM t2, t3;

ALTER TABLE t1 ADD PRIMARY KEY (a, b(255), c(255)), ADD KEY (b(767));

EXPLAIN SELECT * FROM t1 WHERE b LIKE 'adfd%'\G
--- cut ---

Before r2667:

*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: t1
         type: range
possible_keys: b
          key: b
      key_len: 769
          ref: NULL
         rows: 2
        Extra: Using where
1 row in set (0.00 sec)

After r2667:

*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: t1
         type: ALL
possible_keys: b
          key: NULL
      key_len: NULL
          ref: NULL
         rows: 6
        Extra: Using where
1 row in set (0.00 sec)

The change can be observed by only applying the attached patch
(bzr diff -r2666..2667 sql/sql_table.cc).

Do you have any idea whether this is expected or it is some
side-effect or it is a bug?

Thank you!

-- 
Vasil Dimov
moc.elcaro@stripped        Software Developer @ Oracle/Innobase Oy
gro.DSBeerF@dv                Committer @ FreeBSD.org
gro.d5v@dv                    Home @ Sofia, Bulgaria

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