Latch and Resource Activity
The latch and resource activity dashboard provides detailed statistics on latch usage and waits. Many of the performance issues related to latch and resource waits can be resolved with simple configuration changes.
Each graph is described below.
These graphs show latch activity and waits. It is difficult to define "high" latch activity as it is directly correlated to database activity. You should attempt to minimize latch waits as much as possible.
In a very well tuned system such as this one, we see only a few dozen MTX latch waits per second during business hours, even though database reads are in the millions per second.
|AIB||After-image buffer and control blocks|
|BF1-4||Roll-up counters for buffer pool block latches|
|BFP||Buffer pool control blocks|
|BHT||Buffer pool hash table|
|BIB||Before-image buffer and control blocks|
|CDC||Change Data Capture ??|
|CPQ||Checkpoint queue latches|
|GST||Global storage pool latch|
|LHT||Lock table hash chains|
|LHT2||Lock table hash chains|
|LHT3||Lock table hash chains|
|LHT4||Lock table hash chains|
|LKF||Lock table free chain|
|LKP||Lock table purge chain|
|LRU||Buffer pool LRU chain|
|MTX||BI log space allocation and microtransaction|
|PWQ||Page writer queue|
|SCC||Shared schema cache|
|SEQ||Sequence cache latches|
|TXQ||Transaction queue latches|
|TXT||Transaction table latches|
|USR||User table latches|
These graphs show resource requests and waits. Similar to latches, our goal is to minimize resource waits.