Wednesday, February 19, 2020

The Unexpected Benefits Of Conn Flags Count

Some Foxhound 5 connection flags are more important than others, like #9 - Long uncommitted:

Performance Tip: This Flag is useful if you want to be warned when a single connection is sucking all the air out of the room; i.e., when a long-running transaction has a performed a large amount of work that is not yet committed to the database.
Other connection flags might not be so important, especially if they appear for single connections. For example, Connection Flag #15 - Index add rate might just mean one connection is doing a bit more work than normal.

But what if many connections each have one flag set, or worse, what if many connections have many flags?

That's where Conn Flags Count comes in

At the database sample level, Conn Flags Count is the total number of connection flags set across all connections for one sample; large values will draw your attention to where there may be many bottlenecks:
At the connection level, Conn Flags Count is the number of connection flags set for one connection. You can sort the connections to bring the interesting connections to the top:

Conn Flags Count Was An Afterthought

When the Connection Flags feature was first added to Foxhound 5,
  • the flags_set_count column wasn't displayed,

  • then it was displayed in the Connections section because "if it's worth calculating, it's worth showing",

  • then it was made sortable because "if it's worth showing, it's worth sorting",

  • then the Samples & Messages section got its own Conn Flags Count,

  • and the Peaks row got one too:
Now Conn Flags Count has become a valuable feature in its own right.

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