mslink Column

The mslink column serves as a primary key for the table. This means that any row can be uniquely specified solely by its mslink column value.

Key Index

When a SELECT, UPDATE, or DELETE statement is submitted, the specified table is searched. Indexes are used whenever available to speed the search. An index is a linked list that contains only the column of interest and its row number in the table. Indexes are optional, but they greatly improve performance. Any column in a table can have its own index. Of course each index takes disk space, so you need to make a trade-off between files size and performance.

As the mslink column is the primary key for a table, it makes sense to create an mslink index. You must create this index using your database program. Bentley recommends you create this index as a unique index and do not allow NULLS in the mslink column.