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NH ProfWhy you should use it

This is a screen shot one of NH Prof’s users has sent me:


A picture is worth a thousand words, I believe is the saying. But in this case, I think it is worth about 1755 queries.

More posts in "NH Prof" series:

  1. (09 Dec 2010) Alert on bad ‘like’ query
  2. (10 Dec 2009) Filter static files
  3. (16 Nov 2009) Exporting Reports
  4. (08 Oct 2009) NHibernate Search Integration
  5. (19 Aug 2009) Multiple Session Factory Support
  6. (07 Aug 2009) Diffing Sessions
  7. (06 Aug 2009) Capturing DDL
  8. (05 Aug 2009) Detect Cross Thread Session Usage
  9. (22 May 2009) Detecting 2nd cache collection loads
  10. (15 May 2009) Error Detection
  11. (12 May 2009) Queries by Url
  12. (04 Feb 2009) View Query Results
  13. (18 Jan 2009) Superfluous <many-to-one> update
  14. (18 Jan 2009) URL tracking
  15. (10 Jan 2009) Detecting distributed transactions (System.Transactions)
  16. (06 Jan 2009) The Query Cache
  17. (05 Jan 2009) Query Duration
  18. (24 Dec 2008) Unbounded result sets
  19. (24 Dec 2008) Row Counts


Fabio Maulo

4 minutes was not enough to understand that something should be studied more deeper ?

Frank Quednau

More than 6 alerts per entity? Amazing...


I believe this qualifies as "studying deeper"


A picture is worth a thousand words...

..and you seem too selfish, which is more that a thousand words indeed.


isn't Select N+1 when you select entity after entity, each in its own query?

Then how can you have 890 select N+1s with only 501 entities loaded?

Also, why would there be a large number of individual writes for a select?

Maybe it's because I don't know NH or NHProf, but I don't think I understand this picture fully.



Select n+1 means you're executing the same select statement several times in a session, selects that probably return the same entities. So nothing wrong with the screenshot. Also in the same session he is doing some updates.

Erik van Brakel

This is exactly what my experience was with using NHProf, although less severe. Usually it's not hard to figure out what's happening (or at least get a gut feeling), but with NHProf it's so easy to spot the errors! I was hesitant at first, but when the possibility to use it for Java Hibernate seemed to be possible I was sold ;-)

Brian Henderson

One step forward, two back.. (i.e. One db call, for every 2 alerts) something wrong with this picture. (1735/3534)

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