Re: a bit strange btree index tuples - Mailing list pgsql-hackers

From Tomas Vondra
Subject Re: a bit strange btree index tuples
Date
Msg-id 4DBD4D85.30406@fuzzy.cz
Whole thread Raw
In response to Re: a bit strange btree index tuples  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Dne 1.5.2011 05:30, Tom Lane napsal(a):
> Tomas Vondra <tv@fuzzy.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


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