Обсуждение: BTree index and optimizer

Hello:
I am trying to find out, how is the B-tree index implemented for
multiple columns? does Postgres, justconcatenate the columns --- if this is the case, then how is the
search performed? Also, does the optimizerchoose the index, only when the constraining is on the leading
subset of the index column?
ThanksVJ 

Anand, VJ (MED, GEMS-IT) kirjutas K, 03.12.2003 kell 18:18:
>     Hello:
> 
>     I am trying to find out, how is the B-tree index implemented for
> multiple columns? does Postgres, just
>     concatenate the columns --- 

Yes.

> if this is the case, then how is the
> search performed? Also, does the optimizer
>     choose the index, only when the constraining is on the leading
> subset of the index column?

Yes.

If you want it more complicated, you could check out if PG's R-tree
indexes suit you.

-------------
Hannu