Always declare a cursor’s intent: read-only or updatable. This gives you greater control over concurrency implications. If you do not specify the intent, Adaptive Server decides for you, and very often it chooses updatable cursors. Updatable cursors use update locks, thereby preventing other update locks or exclusive locks. If the update changes an indexed column, the optimizer may need to choose a table scan for the query, resulting in potentially difficult concurrency problems. Be sure to examine the query plans for queries that use updatable cursors.
