Performance Tuning with SQL Server Dynamic Management Views

Chapter 5: Indexing Strategy and Maintenance
each usage in counted once. The operational stats object may have multiple values set
for each type of activity recorded. Finally, note that we cannot use APPLY operators with
this DMF.
Whereas the usage stats give a feel for how an index is used by the optimizer to satisfy the
needs of certain queries, the operational stats offer more detailed information about how
the index is used at a physical level, via columns such as leaf_insert_count, leaf_
update_count and leaf_delete_count (the cumulative number of leaf-level inserts,
updates and deletes), as well as the nonleaf_* equivalents, for modifications above the
leaf level.
For diagnosis of resource contention on the object, the following columns are
particularly useful:
• row_lock_count – number of row locks that have been requested against this index
• row_lock_wait_count – number of times a session has waited on a row lock
against this index
• row_lock_wait_in_ms – amount of time a session had to wait on a row lock against
this index
• page_lock_count, page_lock_wait_count, page_lock_wait_in_ms – same
as row_lock values at the page grain
• index_lock_promotion_attempt_count, index_lock_promotion_count
– number of times the lock grain for an operation using this index was attempted or
granted to be escalated (like from row to page)
• page_latch_wait_count, page_latch_wait_in_ms – number of waits and time
waited on the physical page of the object to have the latch removed
• page_io_latch_wait_count, page_io_latch_wait_in_ms – number of waits
and time while SQL loads pages from disk into memory for an index operation.
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