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Look at the size of my BCHR Expand / Collapse
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Posted Friday, January 9, 2009 12:38 PM
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Comments posted to this topic are about the item Look at the size of my BCHR
Post #633777
Posted Friday, January 9, 2009 2:23 PM


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BWAA-HAAA!!! "I'll show you mine if you show me yours."

I've never looked, but I'm just betting that the BCHR is nearly 100% for cursors... ;)


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Post #633892
Posted Friday, January 9, 2009 2:55 PM
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I have rarely seen anything below 99%, so I don’t pay much attention to it.

I look more at Average Page Life Expectancy and Page Reads/Sec. These seem to be more volatile and let you know how much thrashing of data pages in and out of memory the server is doing and how much of a bottleneck getting data from disk is.



Post #633923
Posted Saturday, January 10, 2009 11:14 AM


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I've honestly stopped checking this at many servers since they're usually > 90%. However I have seen it in the 80s or lower and more memory almost always solves this and gives a little boost.






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Post #634192
Posted Saturday, January 10, 2009 11:32 AM
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well its one of the default performance counters in MOM, which raises a critical alert if it goes below 90% for more than 15 mins (by default) so I guess MS still consider it an indicator of performance.

For myself i admit its nice to see it up high and its something I track as part of memory monitoring but I would only really worry about it if it was ALWAYS low.


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Post #634195
Posted Sunday, January 11, 2009 12:50 AM


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Hi,

Since not all memory requests will reflect in the counter you could have > 90% and still have memory issues (and with issues I don't mean low on memory; over consumption is more often the case :P).

But as Steve pointed out, if you encounter a low BCHR and add some memory, there will usually be a performance boost whereas a high number doesn't necessearily mean all is well.

There could be memory issues elsewhere in the bufferpool - anything that goes through the Memory Broker for instance (large memory requests, queries with sort/hash operators, memory for parallel plans etc.) or in the memory area formerly known as mem_to_leave.

I tend to ignore it completely when it's high.


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Post #634302
Posted Sunday, January 11, 2009 11:39 AM


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By itself it is not a key indicator, but it can be an important clue if you are having performance issues.

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Post #634384
Posted Monday, January 12, 2009 1:56 AM
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I dont use it. I measure the time/ workload it takes to perform different tasks that is prio.
Post #634508
Posted Monday, January 12, 2009 9:20 AM


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I've never bothered with it. Maybe I should, but I never have.

I've found tracking runtime on queries to be much more useful to me in performance tuning.


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Post #634779
Posted Monday, January 12, 2009 9:51 AM


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Interesting you've never used it. I use this as a first glance when I get a complaint about a new server. It's a thumb-sketch to see if this is grossly out of whack.

Once I'm familiar with a server, I'd probably never look at it again.







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Post #634805
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