Mark Lewis wrote:
On Thu, 2006-06-15 at 14:05 -0400, John Vincent wrote:
Now I've been told by our DBA that we should have been able to wholy
satisfy that query via the indexes.
DB2 can satisfy the query using only indexes because DB2 doesn't do
MVCC.
You can get pretty much the same effect with materialized views.
Create a table that LOOKS like the index (just those columns),
with a foreign key relationship to the original table (cascade delete),
and have the after-insert trigger on the main table write a row to the derived table.
Now (index and) query the skinny table.
Advantage of these tables: you can cluster them regularily,
because it doesn't hard-lock the main table.
--
Engineers think that equations approximate reality.
Physicists think that reality approximates the equations.
Mathematicians never make the connection.
