FreeTDS Development Group

[Frediano Ziglio <freddy77 AT gmail.com>]

Il giorno mar, 04/11/2008 alle 20.48 -0800, Man Min Yan ha scritto:
> Hi Frediano,
> 
> You're right, tds_free_dynamic doesn't seem to be right. It's not removing 
> the items from the tds->dyns list properly. Also, my previous patch is not 
> right as it would throw away any previously prepared statement. Here's my 
> 2nd go at fixing this problem.
> 
> I've also tried to identify where the prepares were happening, and it seems 
> to be a freetds problem. Here's the call stack:
>     main()
>     perl_run()
>     Perl_runops_standard()
>     Perl_pp_entersub()
>     XS_DBI_dispatch()
>     XS_DBD__ODBC__st_execute()
>     odbc_st_execute()
>     SQLExecute()    from libodbc.so.1
>     SQLExecute() at odbc.c:3343
>     _SQLExecute() at odbc.c:3142
>     tds_submit_prepare() at query.c:1007
> 
> The code in _SQLExecute is actually un-preparing the statement, 
> re-preparing it, then executing it every time it is called.
> 
> Rgds,
> Man Min
> 

Mmmm... currently there are 3 issues:
- generated ids can create duplication leading to dynamic reuse, perhaps
we should throw error on same id and generate betters ids. TODO: test in
libTDS to check no duplication on generated ids
- on reused dynamic I had cur_dyn set but no dynamic on list... that is
a huge memory problem! TODO: test in odbc to remove the problem
- odbc prepare too much, in this case due to rebinding. TODO: cache
argument and query in libTDS to avoid this case.

freddy77