1 – latch_requests_field
This field displays the total number of latch requests that have occurred. A latch is requested whenever an internal data structure needs to be atomically modified, and indicates a potential stall point. The duration of the latch is essentially non-measureable.
2 – __retried_field
This field indicates the latch could not be immediately acquired and the latch had to be requested again. This field provides an indication of the contention on the row cache. Ideally, this field should be as close to zero as possible.
3 – cache_searches_field
This field displays the total number of times the row cache was searched for a particular row (DBKEY). Values within this field are subdivided into the following fields: found in workset found in cache found too big
4 – __found_in_workset_field
This field indicates the particular row was found in the process' working set and no additional work was required to fetch the row. This is the ideal situation.
5 – __found_in_cache_field
This field indicates the particular row was not found in the process' working set, but was found in the global row cache. When this occurs, it is possible that the process will have to make room in the working set by removing an existing row to the global cache.
6 – __found_too_big_field
This field indicates the particular row was found in the global cache, but the row is now too large to fit into the specified cache buffer. At one time, the row fit into the cache, but it no longer does. Therefore, the cache effectiveness is reduced because a cache entry is reserved for the row but no row caching is possible.
7 – insert_cache_field
This field indicates the total number of times new rows have been inserted into the row cache. Values within this field are subdivided into the following fields: row too big cache full collision
8 – __row_too_big_field
This field indicates the row was initially too large to fit into the specified row cache buffer.
9 – __cache_full_field
This field indicates that all row cache entries were modified and could not be flushed to disk in order to make space for the new row. This is an indication that the row cache checkpointing intervals specified for the database may be too large.
10 – __collision_field
This field displays the total number of row cache hash table collisions that occurred when inserting new rows. This field provides an indication of the effectiveness of the cache size.
11 – VLM requests field
This field displays the number of VLM requests made.
12 – __window_turns_field
This field displays the number of VLM requests made for which the VLM address range was not immediately available.
13 – skipped_dirty_slot_field
This field displays the total number of cache entries that could not be replaced because the slot contained modified data rows. This field provides an indication of the relative amount of work required to find space in order to insert a new row into the cache.
14 – skipped_inuse_slot_field
This field displays the total number of cache entries that could not be replaced because the slot was referenced by other processes. This field provides an indication of the relative amount of work required to find space in order to insert a new row into the cache.
15 – hash_misses_field
This field displays the total number of times the row cache hash table overflowed.
16 – cache_unmark_field
This field displays the total number of times a row in the cache was flushed to disk, thus making it eligible to be replaced. However, this field does not indicate whether or not the row was emptied from the cache.