Hi Stewart,
I think I have solved the low hanging fruit ( Bug # 626893 -
https://bugs.launchpad.net/drizzle/+bug/626893 ).
The changes were made in file create_table.cc ( line # 198 ) . The part of
the code that was sending the error to the client is given below
if (unique_table(create_table_list, select_tables))
{
*my_error(ER_UPDATE_TABLE_USED, MYF(0),
create_table_list->alias);*
/* put tables back for PS rexecuting */
lex().link_first_table_back(create_table_list, link_to_local);
res= true;
break;
}
After looking at how warnings and errors are set in drizzle, I have changed
the following line of code
*my_error(ER_UPDATE_TABLE_USED, MYF(0), create_table_list->alias);*
to
*push_warning_printf(&session(), DRIZZLE_ERROR::WARN_LEVEL_NOTE,
ER_TABLE_EXISTS_ERROR, ER( ER_TABLE_EXISTS_ERROR),create_table_list->alias )
*
Now the desired behavior ( i.e warning instead of error ) is acquired
I am just going to commit this solution so you can review it.
I also sent you a private email regarding some questions about project
proposal and replication code. Please answer my queries.
Regards,
Kinaan Khan Sherwani
On Mon, Mar 26, 2012 at 5:55 PM, Stewart Smith <stew...@flamingspork.com>
wrote:
> Hi!
>
> On Mon, 26 Mar 2012 15:50:27 +0500, Kinaan Khan Sherwani <
mr.sherw...@gmail.com> wrote:
>> Hello,
>>
>> I'm an undergraduate student currently in the 3rd year of my Computer
>> Science degree at *FAST-National University of Computer and Emerging
>> Sciences, Lahore, Pakistan.* I am interested in* "table definition files
>> in an innodb table" *idea under 'Stewart Smith' as a mentor.
>
> Great to meet you!
>
>> For the past few days , I have been studying the mysql innodb storage
>> engine. I studied in mysql reference manual that MySQL server keeps data
>> dictionary information in .frm files which it stores in the database
>> directories, whereas InnoDB also stores the information into its own data
>> dictionary inside the table space files. According to my knowledge , in
>> case of drizzle, the problems occur when the innodb internal data
>> dictionary goes out-of-sync with the table definition files ( same as in
>> mysql ).
>
> correct.
>
>> The GSoC idea is
>> " To make DDL truly crash safe, we should instead store them inside a
>> InnoDB table as part of the data dictionary transaction ".
>> My question is that what is the basic purpose to store the information
>> inside the data dictionary when it is already present there? Why don't we
>> just remove the mechanism of using table definition ( .frm / .dfe ) files
>> so that drizzle just checks the information in data dictionary.
>
> There is more information in the table definition protobuf message than
> just what ends up in the InnoDB data dictionary. This includes: table
> and column comments, default values and even the exact data types of
> each column (many user visible types can map to the one internal innodb
> type).
>
>> I have built the source of Drizzle in Linux. I am curious to know which
>> debugging tool you guys would recommend to use on Linux to debug and
study
>> the source base of Drizzle.
>
> GDB when needed, but if you want to track what storage engine calls
> happen, check out the storage_engine_api_tester plugin test/result files
> to see the traces of some simple queries.
>
>> I intend to solve a bug and I am on it. After starting work on MySQL i
was
>> always interested to work on innodb engine and planned to do it in
summers
>> as I will be totally free. This GSoC project will give me chance to work
on
>> innodb which will also help me in learning MySQL/Drizzle and develop them
>> further.
>>
>> PS. I didn't look into the innodb source so it's just an educated guess
>> based on my learning in previous days. I need an expert opinion on it.
>
> You can have a look at how the replication code writes the replication
> messages to an innodb table, and that will form a template for how to
> write the table protobuf message.
>
> For seeing an engine that implements storing the table definition in a
> table, you can check out the 7.0 source (elliot) and the HailDB engine.
>
> --
> Stewart Smith
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