Davi,

Thanks for the pointers! I'd like to lock an entire database. (I guess I can iterate through the tables in database if that's the only way. [I suppose there might be possible locking issues to deal with ...])

I'll look at the source you recommend ...

Weldon weldon@whipple.org

On Mon, Oct 18, 2010 at 12:48 PM, Davi Arnaut davi.arnaut@oracle.com wrote:

On 10/18/10 3:16 PM, Weldon Whipple wrote:

...

Well, I finished a working prototype that does everything except the locking and unlocking of databases. Someone mentioned that it's now possible to lock individual tables. Would you--anyone--be willing to point me toward places in the 5.5 code that use that locking/unlocking?

Do you want to lock the database, or individual tables, or both? Anyway, take a look at mysql_rm_db as the locking is all very similar. Roughly, the algorithm of a DROP DATABASE is:

// Protect against other schema operations        lock_schema_name("db1");        // Build list of tables in the db1 directory        table_list = ..        // Initialize metadata lock request        table_list->mdl_request.init(MDL_key::TABLE,                table_list->db,                table_list->table_name, MDL_EXCLUSIVE);        // Lock tables        lock_table_names(thd, tables, NULL ...)        // Remove from cache and drop the table...

The best thing at this point is to study (and debug) a similar statement and understand how metadata locks work (mdl prefix) or how tables are open/locked.

Regards,

Davi

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