DBMS timeouts or deadlocks occur when two users attempt to access a database record or table that is locked. Some of the earlier supported DBMS's lock records at page level. Data for different models were stored on the same DBMS page. Because of this, any two users, regardless of the models being accessed or updated, can experience timeouts and deadlocks. Even though it is not easily predictable, certain encyclopedia functions have a tendency to cause timeouts and deadlocks. Model deletion is one of these functions.
These functions, especially when run on large models, perform thousands of DBMS inserts, updates, and deletes to key encyclopedia tables such as DOBJ and DASC. Functions like copy model and upload of a new model may perform thousands of inserts and updates but tend to access new pages rather than existing ones. Model delete accesses existing pages that can be spread across the entire encyclopedia. This amount of activity increases the chance of another user attempting to access the same page of a table or index.
Another group of encyclopedia functions have a tendency to cause timeouts and deadlocks because they are not capable of taking interim commits. Because these functions must force a complete rollback if they fail, they cannot take an interim commit, which causes the DBMS page locks to escalate to tablespace locks when run on a large amount of data. These functions are:
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