Indexed attribute property

You index an attribute to optimize it for fast search results and fast value retrieval. Indexes only improve performance for attributes whose values are stored in the PI AF database. This means that you do not gain any benefit from indexing attributes that obtain their values from data references, as is the case with PI points and linked tables. For event frames, however, when attribute values are captured they are written to the PI AF server and as a result can benefit from indexing.

Note: The Indexed property can only be set for attribute templates. The Indexed property is selected from the Properties menu during attribute template creation. In addition, only the first 40 characters of indexed attributes with a String value type are used in searches.

When you index an attribute, both the attribute and the attribute value are returned more quickly in a search. However, indexed attributes increase the table size in your PI AF database and they create some CPU load on the SQL server. Indexed attributes are marked with the icon.

You typically index an attribute that you think users are likely to search for frequently. For example, if you know that you want to locate assets by searching for a serial number, you should index the serial number attribute.