Thanks a lot! Rongrong
Rongrong On Tue, Sep 9, 2014 at 8:18 AM, Sergey Petrunia <[email protected]> wrote: > On Mon, Sep 08, 2014 at 08:54:00PM +0100, Rongrong wrote: > > I'm trying to implement some feature that requires to get the list of > > fields for a given index. I'm trying to follow the optimizer code to find > > some clue but am not successful so far. Can anyone give me some pointers? > > > > A TABLE object has a member called key_info. It is an array of structures > describing each index. > > For an index $I, table->key_info[$I].usable_key_parts gives the number of > key > parts that the optimizer considers (it varies depending on > extended_keys=on|off > setting), > > Then, table->key_info[$I].key_part is an array of structures describing key > parts. > The most interesting are table->key_info[$I].key_part[$PART].field (the > field > itself) and table->key_info[$I].key_part[$PART].fieldnr (field number). > > > Alternatively, there is table->field[$FIELD_NO].part_of_key - this is a > bitmap > which tells which indexes this field is a part of. > > BR > Sergei > -- > Sergei Petrunia, Software Developer > MariaDB | Skype: sergefp | Blog: http://s.petrunia.net/blog > > >
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