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26.12.3 Performance Schema Instance Tables
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Instance tables document what types of objects are instrumented. They provide event names and explanatory notes or status information:
cond_instances: Condition synchronization object instancesfile_instances: File instancesmutex_instances: Mutex synchronization object instancesrwlock_instances: Lock synchronization object instancessocket_instances: Active connection instances
These tables list instrumented synchronization objects, files,
and connections. There are three types of synchronization
objects: cond, mutex, and
rwlock. Each instance table has an
EVENT_NAME or NAME column
to indicate the instrument associated with each row. Instrument
names may have multiple parts and form a hierarchy, as discussed
in Section 26.6, “Performance Schema Instrument Naming Conventions”.
The mutex_instances.LOCKED_BY_THREAD_ID and
rwlock_instances.WRITE_LOCKED_BY_THREAD_ID
columns are extremely important for investigating performance
bottlenecks or deadlocks. For examples of how to use them for
this purpose, see Section 26.19, “Using the Performance Schema to Diagnose Problems”
Document created the 26/06/2006, last modified the 26/10/2018
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