There are some performance considerations that must be made
when using DB2NSF. The two biggest areas of concern are the number
of DB2NSF databases per group, and the design of DB2NSF enabled databases.
It should be noted that using DB2NSF will never be faster than just
using a normal NSF database. There is overhead when using DB2NSF
(namely integrating DB2 into Domino), where when just using a normal NSF
database you only have Domino to act as a performance barrier.
Number of Databases per Group
Domino groups DB2NSF enabled databases to try to increase
performance when performing SQL queries against them. In DB2, these
groups are schemas, and the reasons that grouping these databases
increases performance when performing SQL queries against the DB2NSF enabled
databases is that DB2 caches SQL queries across an entire schema. The
default number of databases per group is 10. There is a downside
to having a larger number of databases per group. The largest downside
is that if at any time Domino needs to get a lock on one of the databases
in the group, it can only do so by locking the whole group of databases.
This type of lock occurs for example, when a database is queued to
be deleted, or being deleted. While the group is locked, there will
be severe performance hits taken until the lock is released. Because
of the downside, it is generally recommended to change the number of databases
per group to 1 unless you are performing similar queries to multiple databases
and you would gain a significant advantage in having them grouped together.
It is not recommended to take an existing database and
just drop it into DB2. Databases enabled for DB2NSF should be done
so to accomplish a specific purpose, and as such should be designed specifically
for DB2NSF. This being the case, if you want to move a database to
DB2, you very well might have to re-design the entire database. Some
examples of database design that do well in DB2 can be found here:
Domino DB2 Integration Features to Enhance the Functionality and Performance
of Domino Applications
It is strongly recommended that no mail files are ever
moved to DB2. Unfortunately the default setting for Database creation
type is DB2. This causes all new databases, be it mail files, databases
not specifically designed for DB2, etc to be moved to DB2 uneccesarily.
It is strongly recommended that the Database creation type be set
- JCUS6W9QKH - DB2 - Unusable performance when using categorized