pbxt-discuss team mailing list archive

[Brian Aker <brian@xxxxxxxxxxx>]

Hi!

If you know the table name you can do a getTableDefinition() for the table and get back the definition. Do you need anything beyond that?

Cheers,
	-Brian

On May 10, 2010, at 1:20 AM, Paul McCullagh wrote:

> Yup, This is a C hack, so I agree it should be done differently for Drizzle.
> 
> my_close_table() is only used to close "tables" opened by my_open_table().
> 
> In my_open_table() we have:
> 
> 	if (!(buffer = (char *) xt_malloc(self, size)))
> 		return NULL;
> 	table = (TABLE *) buffer;
> 	buffer += sizeof(TABLE);
> 	share = (TABLE_SHARE *) buffer;
> 
> So things have been setup so that:
> 
> share == (TABLE_SHARE *) ((char *) table + sizeof(TABLE))
> 
> To get rid of this hack, we need to look at the purpose of this code:
> 
> PBXT requires a reference (or a copy of) the internal MySQL/Drizzle data dictionary (i.e. the structure that is created when a .frm file is loaded).
> 
> This is required for 2 purposes:
> 
> 1. To determine the internal MySQL row and key structures.
> 2. PBXT uses reference to MySQL collation sequence based comparison routines.
> 
> MySQL/Drizzle supply this reference when opening a table handler. However, for PBXT this is not good enough, because there are background threads (like the recovery thread) that need the information as well.
> 
> Ideally Drizzle would supply a set of callback services. One of these would be to get a reference to Drizzle data dictionary for a table, and another would be a function to release the reference.
> 
> Then I could remove the hack for the Drizzle case entirely.
> 
> On May 9, 2010, at 1:24 AM, Brian Aker wrote:
> 
>> Hi!
>> 
>> This code:
>> 
>> static void my_close_table(TABLE *table)
>> {
>> #ifdef DRIZZLED
>>       TABLE_SHARE     *share;
>> 
>>       share = (TABLE_SHARE *) ((char *) table + sizeof(TABLE));
>>       share->free_table_share();
>> #else
>>       delete_table(table, true);  // TODO: Q, why did Stewart remove this?
>> #endif
>>       xt_free_ns(table);
>> }
>> 
>> 
>> This is not going to go well in Drizzle, since we the assumption that the memory allocation will be aligned this way is wrong. In my local tree I am going to drop the free_table_share().
>> 
>> I'm not really sure what to do though. I believe what you will be wanting to do is call delete on table->s, though if what you are using is an TableInstance then it should clean up just fine on its own.
>> 
>> Is there something I can do to make this code a bit more straightforward for you?
>> 
>> Cheers,
>> 	-Brian
>> 
>> 
>> 
>> 
>> 
>> 
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> 
> 
> 
> --
> Paul McCullagh
> PrimeBase Technologies
> www.primebase.org
> www.blobstreaming.org
> pbxt.blogspot.com
> 
> 
>