Re: b-tree index search algorithms

Am 18.07.12 23:56, schrieb Tom Lane:
> Samuel Vogel <s@muel-vogel.de> writes:
>> How would the b-tree know exactly that a value is only a reference? And
>> even in that case you say that it could get the bits, but make no use of
>> it, since it does not know what they represent, right?
> It has access to the data type's basic storage parameters, which are
> typbyval, typlen, and typalign; and we have standard conventions for
> identifying the length etc of variable-length values.  It's just the
> meaning of the payload data bytes that's data-type-private.

Okay, so with these I know if and how I would have to "dereference" the 
data.
But how do I get to this info from inside _bt_binsrch? 
RelationGetDescr(rel)->tdtypeid was my closest guess, but I need to get 
a reference to FormData_pg_type somehow.

Regards,
Samuel Vogel