Cache Statistics
The cache statistics record (type 1) is listed in the following table.
| Statistic | Description |
|---|---|
| Record type | Integer value representing the type of statistics sampling record |
| Node number | Node number relative to the system |
| Process number | Process number relative to the system |
| Clock ticks | 64-bit number of microseconds elapsed since the node was initialized |
| Node CPU time | 64-bit number of microseconds of CPU time charged for node |
| Node ticks | 64-bit number of logical operations performed by the node |
| Process CPU time | 64-bit number of microseconds of CPU time (including start process CPU time and end process CPU time) charged for the process |
| Process ticks | 64-bit number of logical operations performed by the process |
| Process logical clock | Sequential 64-bit number for inter-node process context switches |
| User number | Number supplied by the write sample request |
| User text | Text supplied by the write sample request |
| Cache type | For details, see "Cache Type", later in this chapter |
| Hits | 64-bit number of cache requests to existing buffers |
| Misses | 64-bit number of cache requests to non-existing buffers |
| Top of LRU hits | 64-bit number of requests where the buffer was at the top of the LRU (least-recently used) chain |
| Created buffers | 64-bit number of buffers created |
| Clean swapped buffers | 64-bit number of buffers swapped with no put operation |
| Dirty swapped buffers | 64-bit number of buffers swapped with put operation |
| Resized buffers | 64-bit number of buffers resized |
| Maximum buffer size | Maximum size (in bytes) allowed for the cache |
| Total number of buffers | Number of current buffers in cache |
| Available buffer size | Current available size (in bytes) |
| Maximum overdraft buffer size | Maximum size (in bytes) allowed for the process overdrafts |
| Overdraft buffer size | Current overdraft size (in bytes) for process overdrafts |
| Total cumulative operations | 64-bit number of total cumulative logical operations for all buffers (a logical operation is equivalent to an access in cache) |
| Total current operations | 64-bit number of total logical operations for all buffers currently in cache |
| Deleted buffers | 64-bit number of buffers deleted (that is, removed from cache) |
| Dead buffers | 64-bit number of total cumulative buffers marked as dead (that is, pending deletion) |
| Copied buffers | 64-bit number of buffers that were copied due to being resized |
| New buffers | 64-bit number of buffers created for new objects |
| Total fetches | 64-bit number of times an object was fetched from the database to be placed in cache |
| Duplicate fetches | 64-bit number of times an object was fetched from the database but not copied into the cache because the same or later edition was already in cache |
| Stubbed buffers | 64-bit number of times buffers containing an uncommitted update were converted to stubs (that is, minimally-sized buffers) instead of being swapped out of cache |
| Swapped buffers | 64-bit number of times buffers were removed from cache to make room for other buffers |
| Total operations when swapped | 64-bit number of total logical operations for all swapped buffers (that is, removed from cache to make room for other buffers) |
| Minimum operations when swapped | 64-bit number |
| Maximum operations when swapped | 64-bit number |
| Total age when swapped | 64-bit number of total age for all swapped buffers (age is measured in node ticks elapsed since the buffer was created) |
| Minimum age when swapped | 64-bit number |
| Maximum age when swapped | 64-bit number |
| LRU traversals | 64-bit number of recordings for the top of LRU processing to the bottom position |
| Total LRU traversal ticks | 64-bit number of total elapsed node ticks for all LUR traversals |
| Latest LRU traversal ticks | 64-bit number of node ticks elapsed for the latest recording of top of LRU processing to the bottom position |
| Total cache coherency notifications | Total number of cache coherency notifications received |
| Cache coherency notification hits | Number of cache coherency notifications that resulted in objects in cache being made obsolete |
| Cache coherency updated objects | Number of objects that have been updated |
| Cache coherency object hits | Number of objects listed in cache coherency notifications that were found in cache |
| Cache coherency object misses | Number of objects listed in cache coherency notifications that were not found in cache |
| Cache coherency range requests | Only for internal use by JADE |
| Node lock remove requests received | Number of requests received to remove a node lock |
| Node lock remove requests sent | Number of requests sent to remove a node lock |
| Node lock swap out requests sent | Number of requests sent to remove a node lock due to a stable object being removed from the cache |
For details about the
An LRU traversal represents the time, measured in elapsed node ticks, it would take a buffer at the top if the LRU chain to progress to the bottom position, assuming it is not referenced again.
