From: Zardosht Kasheff
Date: September 22 2010 4:09am
Subject: Re: question on mysql_alter_table
List-Archive: http://lists.mysql.com/internals/38108
Message-Id: <AANLkTikaRZ_Bdu4-qmMonUX1onTRd8RxfOevOxaQ1sFK@mail.gmail.com>
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Hello all,

Any ideas on how to do this? I guess what I am looking for is some way
to differentiate between using new_mysql_alter_table and
old_mysql_alter_table. I thought one way would be to query flags of
the engine of the table being altered, but if that is too complicated,
perhaps some other idea works?

Thoughts?

Thanks
-Zardosht

On Mon, Sep 20, 2010 at 12:26 AM, Zardosht Kasheff <zardosht@stripped> wro=
te:
> Hello all,
>
> I am trying to make a change to mysql_alter_table, but I want the
> change to apply only when the table being altered is created with my
> storage engine. So, I have two different versions of mysql_alter_table
> written, one named old_mysql_alter_table, which is the current
> functionality, and the other is new_mysql_alter_table, which has my
> changes.
>
> I would like to implement mysql_alter_table as such:
> =A0 =A0if (use_new) {
> =A0 =A0 =A0 =A0return new_mysql_alter_table(
> =A0 =A0 =A0 =A0 =A0 =A0thd,
> =A0 =A0 =A0 =A0 =A0 =A0new_db,
> =A0 =A0 =A0 =A0 =A0 =A0new_name,
> =A0 =A0 =A0 =A0 =A0 =A0create_info,
> =A0 =A0 =A0 =A0 =A0 =A0table_list,
> =A0 =A0 =A0 =A0 =A0 =A0alter_info,
> =A0 =A0 =A0 =A0 =A0 =A0order_num,
> =A0 =A0 =A0 =A0 =A0 =A0order,
> =A0 =A0 =A0 =A0 =A0 =A0ignore
> =A0 =A0 =A0 =A0 =A0 =A0);
> =A0 =A0}
> =A0 =A0else return old_mysql_alter_table(
> =A0 =A0 =A0 =A0thd,
> =A0 =A0 =A0 =A0new_db,
> =A0 =A0 =A0 =A0new_name,
> =A0 =A0 =A0 =A0create_info,
> =A0 =A0 =A0 =A0table_list,
> =A0 =A0 =A0 =A0alter_info,
> =A0 =A0 =A0 =A0order_num,
> =A0 =A0 =A0 =A0order,
> =A0 =A0 =A0 =A0ignore
> =A0 =A0 =A0 =A0);
>
> I do not know how to evaluate use_new. Ideally, I would do something
> like the following:
> =A0 =A0ulong alter_flags=3D 0;
> =A0 =A0alter_flags=3D table_list->table->s->db_type() ?
> table_list->table->s->db_type()->alter_table_flags(alter_info->flags)
> : 0;
> =A0 =A0bool use_new =3D (alter_flags & HA_FLAG_THAT_ONLY_MY_ENGINE_HAS) ?=
 true:false;
>
> The problem is that table_list->table is not yet set, and I do not see
> how to get easily get access to the table that is about to be altered.
>
> Any ideas on how I could solve this problem?
>
> Thanks
> -Zardosht
>