Hi,
Is there any "rule of thumb" on when to (not) use clustered indexes?
What appen to the table/index? (any change on the physical organisation?)
I've seen speed improvement on some queries but I'm not sure if I must use
them or not...
My rows are imported in batch of 100 (once the main script ha
The key expense in doing an index scan is the amount of randomness
involved in reading the base table. If a table is in the same order as
the index then reading the base table will be very fast. If the table is
in a completely random order compared to an index (it's correlation is
low), then an ind
Ok thank you,
so I can consider using clustered indexes when I need to 'reorder' random
data to improve the speed of a particular query...
In simple words:
Clustered indexes are like the alphabetical index in a book, where term are
randomly distibuted in the book and regular indexes are more like
On Wed, 2005-11-02 at 13:50, MaXX wrote:
> Ok thank you,
> so I can consider using clustered indexes when I need to 'reorder' random
> data to improve the speed of a particular query...
>
> In simple words:
> Clustered indexes are like the alphabetical index in a book, where term are
> randomly di
On Wed, Nov 02, 2005 at 08:50:45PM +0100, MaXX wrote:
> Ok thank you,
> so I can consider using clustered indexes when I need to 'reorder' random
> data to improve the speed of a particular query...
>
> In simple words:
> Clustered indexes are like the alphabetical index in a book, where term are
Jim C. Nasby wrote:
> On Wed, Nov 02, 2005 at 08:50:45PM +0100, MaXX wrote:
[...]
>> In simple words:
>> Clustered indexes are like the alphabetical index in a book, where term
>> are randomly distibuted in the book and regular indexes are more like the
>> table of content...
>> Right?
> You have t
Scott Marlowe wrote:
> On Wed, 2005-11-02 at 13:50, MaXX wrote:
[...]
>> In simple words:
>> Clustered indexes are like the alphabetical index in a book, where term
>> are randomly distibuted in the book and regular indexes are more like the
>> table of content...
>> Right?
> Not really. It's more
On Wed, Nov 02, 2005 at 10:55:36PM +0100, MaXX wrote:
> Jim C. Nasby wrote:
> > On Wed, Nov 02, 2005 at 08:50:45PM +0100, MaXX wrote:
> [...]
> >> In simple words:
> >> Clustered indexes are like the alphabetical index in a book, where term
> >> are randomly distibuted in the book and regular index
"Jim C. Nasby" <[EMAIL PROTECTED]> writes:
> That's because unfortunately PostgreSQL only keeps statistics on
> individual columns. There's no stats kept on multi-column indexes; the
> best the planner can do is use the stats for the first column.
That's not what we do at all: we do look at the st
