Database Snapshot Performance

Hi,
I'm developing a Data Mart and i'm experiencing a performance gap
between my fact table and its snapshot.
I create snapshot with the istruction:
CREATE DATABASE DB_SNAP ON ( NAME = DB_SNAP_Data, FILENAME = 'C:
\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\Data
\DB_SNAP_Data.ss' ) AS SNAPSHOT OF DB;
And it works. But executing queries on the snapshot result very
"Slow".
Can anyone tell me why?
Tanks.
F.A snapshot is slow because it makes a copy of of modified data in tempdb.
Thus reads are scattered all over. The real question is why would you NEED
a snapshot of a fact table? This is non-standard DW practice AFAIK.
TheSQLGuru
President
Indicium Resources, Inc.
"Johnny" <xxx.johnny@.gmail.com> wrote in message
news:1171290125.043815.129030@.v33g2000cwv.googlegroups.com...
> Hi,
> I'm developing a Data Mart and i'm experiencing a performance gap
> between my fact table and its snapshot.
> I create snapshot with the istruction:
> CREATE DATABASE DB_SNAP ON ( NAME = DB_SNAP_Data, FILENAME = 'C:
> \Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\Data
> \DB_SNAP_Data.ss' ) AS SNAPSHOT OF DB;
> And it works. But executing queries on the snapshot result very
> "Slow".
> Can anyone tell me why?
> Tanks.
> F.
>