Updates

Number of deferred and direct row updates. The “% of total” column reports the percentage of each type of update as a percentage of the total number of row updates. sp_sysmon reports the following types of updates:

“APL Direct Cheap” in the “Fully Logged” section indicates the number of fully logged all-pages-locked direct updates. “APL Direct Cheap” in the “Minimally Logged” section, refers to the number of minimally-logged all-pages-locked direct updates that occured.

Direct updates incur less overhead than deferred updates and are generally faster because they limit the number of log scans, reduce locking, save traversal of index B-trees (reducing lock contention), and can save I/O because Adaptive Server does not have to prefetch pages to perform modification based on log records.

For a description of update types, see Chapter 1, “Understanding Query Processing,” in Performance and Tuning Series: Query Processing and Abstract Plans.


Total Rows Updated

Reports all deferred and direct updates combined. The “% of total” columns shows the percentage of rows updated, based on all rows modified.