Обсуждение: type of b-tree

Hi, could anybody tell me which variation of B-tree PostgreSQL uses, that
it can handle more than one column?
Some link would be great.
Thanks,
       David Hoksza

David Hoksza <david.hoksza@seznam.cz> writes:
> Hi, could anybody tell me which variation of B-tree PostgreSQL uses, that
> it can handle more than one column?

Plain old b+ tree ... we just treat the keys as compound, ie the
"compare" operation compares columns until finding a difference.

> Some link would be great.

Use the source Luke ...

http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/nbtree/

            regards, tom lane

OK, thanks. And I would like have one more question about B-tree index
- how many records are usualy stored in one node (what's arity of the tree)?

Thanks,
       David Hoksza

________________________________
23. července 2006, 20:03:03, napsal jste:

TL> David Hoksza <david.hoksza@seznam.cz> writes:
>> Hi, could anybody tell me which variation of B-tree PostgreSQL uses, that
>> it can handle more than one column?

TL> Plain old b+ tree ... we just treat the keys as compound, ie the
TL> "compare" operation compares columns until finding a difference.

>> Some link would be great.

TL> Use the source Luke ...

TL> http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/nbtree/

TL>                         regards, tom lane