Friday, 28 May 2010

Encyclopaedia Performance

A few customers have asked us for information on improving performance on both the Gen host ency and client/server ency. Rather than try and write out a definitive list of things to look for, I thought it would be useful (and less onerous) to provide occasional posts on this subject.

If you have any ideas or experiences that you would like to share, then please add comments to the postings, or if you prefer, e-mail them and they can be included in a new post.

The areas that will be considered in this section include encyclopaedia server performance, reducing contention, working practices and other factors that affect the overall performance of the encyclopaedia.

To start things off:

1) Model size rather than overall ency size has a big impact on performance. Smaller models perform much better than larger ones for the same function, i.e. downloading the same subset from a small model will be much faster than a large model. The speed is roughly proportional to the model size.

2) Encourage 'right sizing' subsets and working practices that are efficient, like only generating changed objects rather than all action blocks in a load module.

1) Use the support client and check the Object Cache setting. The default is far too low. We have ours set to 500,000

2) Database i/o has a major impact on performance. Does your DBMS have enough memory for caching? Oracle likes a lot!

Have you implemented DB2 type 2 indices for the encyclopaedia? Originally (many years ago now) these were not available for DB2, so if you have an old encyclopaedia, you may not have converted the indices to type 2. This can have a big impact on contention. Type 1 indices are not supported from DB2 v8 onwards, so if you are on v8, then this will have been taken care of.

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