Performance Tuning with SQL Server Dynamic Management Views

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Introduction
on those objects that, as DBAs, we find most useful in periodic to day-to-day
troubleshooting. We'll describe the most important columns that these DMOs return,
and provide a core set of scripts that can be saved and adapted for your own environment,
to shine some light on previously dark corners of SQL Server performance optimization.
In the process, we'll cover about a third of the total number of available DMOs, spanning
6 of the available 19 categories of DMO, outlined below.
Execution related – Chapters 2 and 3 show how to investigate the activity generated by
SQL statements executed against our SQL Server instances, and how to establish a chain
of ownership, from the user connections, to the sessions they spawn, to the resulting
requests that generate the SQL workload. Chapter 2 focuses on activity that is occurring
right now, on a given instance, and Chapter 3 takes a more historical perspective,
examining CPU, I/O, and memory use by statements for which a plan exists in the cache,
and also investigating critical issues such as plan reuse.
Transaction related – Chapter 4 steps down to the transaction level, showing how
to pinpoint locking and blocking issues, expose open but inactive transactions, and
investigate transactions that are causing substantial transaction log writes. It also
covers those DMOs dedicated to snapshot isolation level, and use of the version store
in tempdb.
Index related – Defining an effective indexing strategy is the best way to ensure that the
most significant and frequent queries in your workload are able to read only the required
data, and in a logical, ordered fashion, thus returning that data quickly and efficiently,
with minimal I/O. The DMOs in this category, covered in Chapter 5, are among the most
frequently used by DBAs, and we'll provide scripts for investigating index use, missing
indexes and index fragmentation.
Database related and I/O related – A critical aspect of SQL Server performance is how
the engine uses the disk I/O subsystem, and the ability of that subsystem to cope with
the I/O throughput (I/Os per second) demanded by the system workload. Chapter 6
investigates those DMOs that expose I/O activity at the file, database, and even table level,