Database Reference
In-Depth Information
Figure 28-13.
SQL Server 2008/2008R2 Extended Events targets
Figure 28-14.
SQL Server 2012-2014 Extended Events targets
Now let's look at targets in greater depth.
The
ring_buffer
target stores data in an in-memory ring buffer of a predefined size.
When it is full, new events override the oldest ones in the buffer. Therefore, events can be
consumed indefinitely. However, only the newest events are retained. This target is most
useful when you need to perform troubleshooting and do not need to retain event data
afterwards. This is an asynchronous target (more about it later).
The
asynchronous_file_target
(SQL Server 2008/2008R2) and
event_file
(SQL Server
2012/2014) targets store events in the file using a proprietary binary format. These targets
are most useful when you want to retain raw event data collected by a session. These targets
are asynchronous.
The
etw_classic_sync_target
is a file-based target, which writes data in a format that
can be used by ETW-enabled readers. This target is used when you need to correlate SQL
Server events with Event Tracing events that are generated by Windows Kernel and other
non-SQL Server components. (These scenarios are outside of the scope of this topic.) This
is a synchronous target.
The
synchronous_event_counter
(SQL Server 2008/2008R2) and the
event_counter
(SQL Server 2012/2014) targets count the number of occurrences of each event in an
event session. This target is useful when you need to analyze the particular metrics from
a workload without introducing the overhead of full event collection. You can think
about counting the number of queries in the system as an example. These targets are
synchronous.
The
synchronous_bucketizer
(SQL Server 2008/2008R2),
asynchronous_bucketizer
(SQL Server 2008/2008R2), and
histogram
(SQL Server 2012/2014) targets allow you to
count the number of specific events, grouping the results based on a specified event data
column or action. For example, you can count the number of queries in the system on
a per-database basis. The bucketizer targets in SQL Server 2008/2008R2 can be either
synchronous or asynchronous, while the histogram target is asynchronous.
