Hi, Alexey!
On Feb 19, Alexey Botchkov wrote:
Hi, Sergei.
Could you, please remove that piece of fine creativity and
thd->clear_error() too and use the error handler instead?
There's one puzzle.
This field is set here:
sql_show.cc:4899 (get_schema_tables_record())
if (res || info_error)
{
/*
If an error was encountered, push a warning, set the TABLE COMMENT
column with the error text, and clear the error so that the operation
can continue.
*/
const char *error= thd->is_error() ? thd->stmt_da->message() : "";
table->field[20]->store(error, strlen(error), cs);
if (thd->is_error())
{
push_warning(thd, MYSQL_ERROR::WARN_LEVEL_WARN,
thd->stmt_da->sql_errno(), thd->stmt_da->message());
thd->clear_error();
}
}
As we're supposed to block that error with the Error_handler, the
error message gets lost there and cannot be recovered later in the
get_schema_tables_record. So we either have stop showing the error
message in that field, or we have to store it somewhere.
The Error_handler looks like a good place to store that error message.
But i can't figure out how to send it to the
get_schema_tables_record() nicely. Another place is the TABLE_LIST *
parameter. Seems to be convenient for everything. Though the
TABLE_LIST structure will get even more polluted.
Error handler looks perfect - it could have a char[] buffer and remember
there the first error message for SHOW TABLES.
But I agree that it's difficult to reach from get_schema_tables_record().
One option would be to use
THD::get_internal_handler()
it'll allow you to access the current error handler. The problem with
this solution - there's no easy way to verify that you've got an object
of the correct class. If someone has pushed another error handler after
you, this will crash.
Another solution could to have a char* pointer in THD or TABLE_LIST and
set it to point to this buffer. This will work even if there's another
handler on top of yours. But it'll need a pointer in THD or TABLE_LIST.
I'd probably use the THD::get_internal_handler() approach and a test
case for it (it'll make sure the calling convention is maintained).
Seems silly to add another member to THD or TABLE_LIST that are used
literally everywhere only to show an open table error in I_S.TABLES.
Regards,
Sergei
