MySQL Bugs: #27806: table comments not passed in to storage engine during "CREATE ... LIKE ..."

Bug #27806	table comments not passed in to storage engine during "CREATE ... LIKE ..."
Submitted:	13 Apr 2007 11:17	Modified:	9 Aug 2007 13:26
Reporter:	Yoshinori Matsunobu	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: General	Severity:	S3 (Non-critical)
Version:	5.1.17	OS:	Any
Assigned to:	Konstantin Osipov	CPU Architecture:	Any
Tags:	HA_CREATE_INFO, Storage Engine API

Description:
When creating table by "CREATE ... LIKE ...", 
table comment is not passed into to the 
storage engine's ::create method.

How to repeat:
create table test.t1 (a int primary key comment "aaa")
   max_rows=1000 comment "bbb";
create table test2.t1 like test.t1;

gdb trace at "create table test2.t1 like test.t1;":
Breakpoint 1, ha_myisam::create (this=0x93cad00, name=0xb4b80d60 "./test2/t1",
    table_arg=0xb4b7f538, ha_create_info=0x93c8b60) at ha_myisam.cc:1778
1778      uint create_flags= 0, records, i;
(gdb) print *ha_create_info
$4 = {table_charset = 0x0, default_table_charset = 0x8715580, connect_string = {
    str = 0x0, length = 0}, password = 0x0, tablespace = 0x0, comment = {str = 0x0,
    length = 0}, data_file_name = 0x0, index_file_name = 0x0, alias = 0x93c8988 "t1",
  max_rows = 1000, min_rows = 0, auto_increment_value = 0, table_options = 8,
  avg_row_length = 0, used_fields = 0, key_block_size = 0, merge_list = {elements = 0,
    first = 0x0, next = 0x0}, db_type = 0x9372428, row_type = ROW_TYPE_DEFAULT,
  null_bits = 0, options = 0, merge_insert_method = 0, extra_size = 0,
  table_existed = false, frm_only = false, varchar = false,
  storage_media = HA_SM_DEFAULT}

Suggested fix:
diff -up table.cc.orig   table.cc
--- table.cc.orig      2007-04-13 15:46:50.000000000 +0900
+++ table.cc    2007-04-13 15:47:36.000000000 +0900
@@ -2217,6 +2217,7 @@ void update_create_info_from_table(HA_CR
   create_info->row_type= share->row_type;
   create_info->default_table_charset= share->table_charset;
   create_info->table_charset= 0;
+  create_info->comment= share->comment;

   DBUG_VOID_RETURN;
 }

Thank you for a problem report. Sorry, but I can not repeat the behaviour described with latest 5.1.18-BK on Linux:

openxs@suse:~/dbs/5.1> bin/mysql -uroot test
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.1.18-beta Source distribution

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql> drop table t1;
Query OK, 0 rows affected (0.01 sec)

mysql> drop table t2;
Query OK, 0 rows affected (0.01 sec)

mysql> create table test.t1 (a int primary key comment "aaa")    max_rows=1000
comment "bbb";
Query OK, 0 rows affected (0.01 sec)

mysql> create table test.t2 like test.t1;
Query OK, 0 rows affected (0.00 sec)

mysql> show create table t2\G
*************************** 1. row ***************************
       Table: t2
Create Table: CREATE TABLE `t2` (
  `a` int(11) NOT NULL COMMENT 'aaa',
  PRIMARY KEY (`a`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 MAX_ROWS=1000 COMMENT='bbb'
1 row in set (0.00 sec)

Maybe, I missed something. Please, check.

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/32237

ChangeSet@1.2561, 2007-08-08 14:02:07+04:00, kostja@bodhi.(none) +1 -0
  Apply patch for Bug#27806 table comments not passed in to storage engine 
  during "CREATE ... LIKE ..."
  Only affects engine writers.
  No change in server behaviour.

Queued in 5.1-runtime

Queued in 5.1-runtime

Pushed into 5.1.22-beta

Internal change only.