Re: a bit strange btree index tuples

Dne 1.5.2011 05:30, Tom Lane napsal(a):
> Tomas Vondra <tv(at)fuzzy(dot)cz> writes:
>> testdb=# select bt_page_items('test_index', 3);
>> bt_page_items
>> ----------------------------------
>> (1,"(1,1)",8,f,f,"")
>> (2,"(2,1)",12,f,f,"ca 01 00 00")
>> (3,"(4,1)",12,f,f,"93 03 00 00")
>> (3 rows)
>
>> I don't understand the first row and I've been unable to find out if
>> it's something special for the btree indexes or what.
>
> You should read src/backend/access/nbtree/README, which would explain to
> you why it is that leftmost tuples on interior btree pages don't contain
> key values.

Thanks, I somehow missed that doc yesterday (ok, it was 3 AM so it's
understandable). I guess the last paragraph in "Notes About Data
Representation" explains this behaviour.

Tomas