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Re: Using GROUP By or @OrderColumn in JPA

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On Fri, 27 Nov 2015 17:43:27 +0100, Silvio wrote:

> On 11/27/2015 05:42 PM, Silvio wrote:
>> On 11/27/2015 03:22 PM, Jerry Stuckle wrote:
>>>
>>> Part of good programming is performance testing - that is, testing
>>> under a typical load you would see in real life.  This includes the
>>> number of concurrent users, database size, typical operations,
>>> hardware being used, etc.  Good testing will show performance
>>> problems.
>>>
>>> Just testing with one user and a minimal database is like an
>>> automobile manufacturer building a car and just testing it at 5mph in
>>> a large, empty parking lot.
>>>
>>>
>> I totally agree but good testing is difficult to organize. A good
>> integration test before a major release as we used to do in the past
>> would indeed uncover 99% of the performance bottlenecks.
>>
>> But nowadays with all the agility going on testing is often equivalent
>> to unit testing which is mostly in this area.
>>
>> I uphold that the majority of performance problems can easily be
>> prevented by the writer of the code given a competent coder.
> 
IME a major problem with sorting out performance during integration or 
system testing is getting anybody at all to say which transactions are 
the most used and/or important from a user POV, let alone getting usage 
volumes. On top of that, even after assuming the DB designer did a good 
job and added indexes etc to support all prime and alternate keys (this 
is often an unwarranted assumption but is usually obvious once you see 
the DB schema), it can be quite hard to find out what else bottlenecks 
the DB. I'm thinking of missing indexes that are needed for some joins or 
to obviate sorting to satisfy ORDER BY clauses. 

As a result, I've often had to instrument the application well enough to 
capture query frequencies and execution times just to find out which 
transactions to tackle first and, that decided, to use JDBC or ODBC 
tracing to see what the problem queries were doing.


-- 
martin@   | Martin Gregorie
gregorie. | Essex, UK
org       |

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Using GROUP By or @OrderColumn in JPA Cecil Westerhof <Cecil@decebal.nl> - 2015-11-25 09:07 +0100
  Re: Using GROUP By or @OrderColumn in JPA Arne Vajhøj <arne@vajhoej.dk> - 2015-11-25 20:02 -0500
    Re: Using GROUP By or @OrderColumn in JPA Cecil Westerhof <Cecil@decebal.nl> - 2015-11-26 07:28 +0100
      Re: Using GROUP By or @OrderColumn in JPA Jerry Stuckle <jstucklex@attglobal.net> - 2015-11-26 08:25 -0500
      Re: Using GROUP By or @OrderColumn in JPA Arne Vajhøj <arne@vajhoej.dk> - 2015-11-26 20:22 -0500
        Re: Using GROUP By or @OrderColumn in JPA Silvio <silvio@internet.com> - 2015-11-27 12:28 +0100
          Re: Using GROUP By or @OrderColumn in JPA Jerry Stuckle <jstucklex@attglobal.net> - 2015-11-27 09:22 -0500
            Re: Using GROUP By or @OrderColumn in JPA Silvio <silvio@internet.com> - 2015-11-27 17:42 +0100
              Re: Using GROUP By or @OrderColumn in JPA Silvio <silvio@internet.com> - 2015-11-27 17:43 +0100
                Re: Using GROUP By or @OrderColumn in JPA Martin Gregorie <martin@address-in-sig.invalid> - 2015-11-27 18:21 +0000
          Re: Using GROUP By or @OrderColumn in JPA Arne Vajhøj <arne@vajhoej.dk> - 2015-11-28 23:01 -0500
            Re: Using GROUP By or @OrderColumn in JPA Silvio <silvio@internet.com> - 2015-11-29 12:42 +0100
        Re: Using GROUP By or @OrderColumn in JPA Arne Vajhøj <arne@vajhoej.dk> - 2015-11-28 22:44 -0500
      Re: Using GROUP By or @OrderColumn in JPA Martin Gregorie <martin@address-in-sig.invalid> - 2015-11-27 11:07 +0000

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