Re: [gnome-db] Meta Store issue with MySQL.

[Bas Driessen <bas driessen xobas com>]

On Thu, 2009-07-30 at 16:17 +0200, Vivien Malerba wrote:
>     
>     
>     2009/7/30 Bas Driessen <bas driessen xobas com>
> >         
> >     
> >         > 2009/7/30 Bas Driessen <bas driessen xobas com>
> >         >
> >         >>  Hello,
> >         >>
> >         >> My database is in MySQL. When I run the following command to rebuild the
> >         >> MetaStore (which lives in a sqlite3 database):
> >         >>
> >         >> gda_connection_update_meta_store(connection, NULL, &error)
> >         >>
> >         >> I get the following error/warning:
> >         >>
> >         >> ** (process:22406): WARNING **: (+5): Wrong Holder value type, expected
> >         >> type 'boolean' when value's type is 'string' (Provider ThreadWrapper)
> >         >>
> >         >>
> >         >> and the MySQL table information is not in the MetaStore. In fact if I
> >         >> do:
> >         >>
> >         >> select * from _tables;
> >         >>
> >         >> nothing shows up.
> >         >>
> >         >> Anyone else having this problem?
> >         >>
> >         >
> >         > The reason for this error is that a SELECT statement internally run by the
> >         > MySQL provider to get meta data returned a column of type string instead
> >         > to
> >         > a boolean. To solve this, the correction consists in locating the faulty
> >         > SELECT, and use gda_connection_statement_execute_select_full() with an
> >         > array
> >         > of expected types for the columns instead of
> >         > gda_connection_statement_execute_select(). This is already done at several
> >         > places in gda-mysql-meta.c.
> >         >
> >         > If you want to try to correct it, and if you are in the master branch, you
> >         > can use the definitions in
> >         > libgda/providers-support/gda-meta-column-types.h
> >         > (which is dynamically generated).
> >         >
> >         > Otherwise, I'd need to have more information to correct the problem
> >         > myself.
> >         
> >         
> >     
> >         OK, I will try to locate and correct the issue in libgda. Just wanted to
> >         have confirmed first that this is an issue in libgda and not in my setup.
> >     
>     
>     To help you, you can uncomment the line 2324 of the gda-meta-store.c file, so you'll get debug info about all the results the provider is returning for the meta store.
>     

Thanks Vivien ... I tried, but it is difficult to get a handle on the flow of code etc. Therefore, I created a small reproducible. Probably faster to get to the core of this issue :)

Steps in the little program below as follows:

-1 Open connection to MySQL. My data source is called "mystock".
-2 Open a data store in sqlite format.
-3 Rebuild the complete store. This will fail. Even if there are no base tables, there should always be something in the _tables for instance. There is nothing there, which probably makes sense as a rollback is triggered if there is a problem.

To check the result:

sqlite3 /tmp/mysql_meta.db

select * from _tables;

Nothing returned.

Can you please test if this is failing in your environment too? The code is as follows:

==============
#include <libgda/libgda.h>

int
main (int argc, char *argv[])
{
        GdaConnection* connection;
        GError* error = NULL;
        GdaMetaStore *store;

        gda_init();
        error = NULL;

        /* open connection */
        printf("Start.\n");
        printf("Open connection.\n");
        connection = gda_connection_open_from_dsn ("mystock", NULL, GDA_CONNECTION_OPTIONS_NONE, &error);
        if (!connection)
        {
                fprintf (stderr, "%s\n", error->message);
                return -1;
        }

        /* Open Meta Store */
        printf("Open Meta Store.\n");
        store = gda_meta_store_new_with_file("/tmp/mysql_meta.db");
        g_object_set(G_OBJECT(connection), "meta-store", store, NULL);
        if (!store)
        {
                printf("Can not open store.\n");
                return -1;
        }

        /* Build Complete store */
        printf("Build complete store.\n");
        if (!gda_connection_update_meta_store(connection, NULL, &error))
        {
                fprintf (stderr, "%s\n", error->message);
                return -1;
        }

        /* The End */
        printf("End.\n");
        return 0;
}

==============

Thanks,
Bas.