Re: Postgres 9.0 has a bias against indexes

On 1/27/2011 3:37 PM, Scott Marlowe wrote:
> On Thu, Jan 27, 2011 at 1:31 PM, Mladen Gogala
> <mladen.gogala@vmsinfo.com>  wrote:
>> There is INDEX UNIQUE SCAN PK_EMP.  Oracle will use an index.
> That's because Oracle has covering indexes.
>
I am not sure what you mean by "covering indexes" but I hope that for
the larger table I have in mind,  indexes will be used.  For a small
table like this, not using an index may actually be a better plan. I
cannot compare because my development PostgreSQL cluster is on a much
weaker machine than the development Oracle database.
I even looked into Wikipedia for the notion of "covering index" and it
is defined as an index which contains all the data requested in a query.
This is not the case, EMP is not an index-organized table. The only
index used was the primary key, also available in the PostgreSQL version
of the table.

--
Mladen Gogala
Sr. Oracle DBA
1500 Broadway
New York, NY 10036
(212) 329-5251
www.vmsinfo.com