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.

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Latches

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.

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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.


Latch Description
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
OM Object cache
PWQ Page writer queue
SCC Shared schema cache
SEQ Sequence cache latches
TXQ Transaction queue latches
TXT Transaction table latches
USR User table latches

Resources

These graphs show resource requests and waits. Similar to latches, our goal is to minimize resource waits.

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