[Serdev] Nested MySQL queries

[Jan Janak]

On 19-09-2005 19:59, Andreas Granig wrote:
> Jan Janak wrote:
> >The problem is that the conversion function does not allocate memory for 
> >strings and binary data, it just points to the memory region allocated by 
> >mysqlclient library. If you call mysql_free_result while the resulting 
> >(converted) data structures are still use then the pointers to strings and 
> >binary data would point to unallocated memory regions.
> 
> Oh, yes, haven't seen this and was surprised about the unexpected 
> results when trying it out a few minutes ago...
> 
> >You would need to make an explicit copy of all strings and binary data
> >before calling mysql_free_result (that would be slower).
> 
> Another possibility which is more elegant IMHO is storing the result in 
> a void-pointer in db_res_t, where it logically belongs to. Would this be 
> a passable solution?

  I don't know what is the internal structure of the data in mysqlclient
  library, the strings are zero terminated so most likely each of them
  has its own memory chunk.

    Jan.