General Lotus Notes View Performance Tips
Here are some tips about view performance, regardless of whether or not reader access controlled documents are present.
Time/date formulas
Using @Now or @Today in a column or selection formula forces a view rebuild every time the view is refreshed. Therefore, if you use this kind of formula, consider making the view refresh Manually or “Auto, at most every n hours.” That way, when users open the view, they will not have to wait for a view rebuild (or rarely so, in the latter case). The downside to this is that the view may be out-of-date because it opened without trying to refresh. Consider the contents of these views and how fast they change to determine whether or not you can use these indexing options safely.
Use click-sort judiciously
Click-sort is a brilliant feature, one that we use in most public views in our applications. But it’s worth checking your hidden lookup views to be sure that no columns have click-sort enabled because having it increases the disk space and indexing requirements without adding any functionality for your users. On this same topic, consider using ascending or descending, but not both, when you use this feature to save on disk space and indexing time without impairing functionality. We would argue that the functionality is preferable when there is only one arrow because it is an on-off toggle rather than a three-way toggle.
Generate unique keys in index
One of the lesser known performance enhancing features, the “Generate unique keys in index” option for lookup views can dramatically improve lookup times. When selected, the view discards all duplicate entries. For example, if you have 400,000 documents all displaying only CompanyName, and there are only 1,000 unique company names, then selecting this feature results in only the first document for each company being held in the view index. Although there is a slight overhead to this feature, it is easily outweighed by the fact that your view may dramatically decrease in size. One warning is that if you are displaying the results of a multi-value field, you need to use a code trick to avoid losing data.
For example, imagine a database has 100,000 documents, all containing a multi-value field called Industry. You want to look up a unique list of industries already selected so that the Industry drop-down list can display the values when users create new documents. If you use this unique keys feature in a view that has a single column displaying Industry, it is possible that a new document containing the values Automotive and Air would not display because another document containing Automotive was already being displayed in the view. Thus, your new value of Air would never be picked up by the lookup formula.
To avoid this problem, use a formula such as @Implode(Industry; “~”) in the column formula, and then the drop-down field lookup formula may be @Explode(@DbColumn(“Notes”; “”; “(LookupViewName)”; 1); “~”). Although you will have some minor duplication of data in your view, you will be guaranteed no data loss.
Color profiles
If you use color profiles (as in the mail template), then any change to that color profile document necessitates a view rebuild for any views that reference that color profile.
Default view
Whenever your application is opened, your default view is opened. Always be sure that this is a view that opens quickly. An interesting example of this is your mail file. For many users, the view that opens by default is the Inbox (folder). If a user is not in the habit of cleaning out her Inbox and if it has many thousands of documents, then it will be slower to open her mail file than if she regularly cleaned out her Inbox and if the view/folder had only dozens or hundreds of documents. Incidentally, this is why some companies have a policy that old documents in the Inbox are deleted periodically. It forces users to move those documents into other folders, thus improving performance both for that user and the server.
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