RE: DWH varchar2(4000)

From: Mark W. Farnham <>
Date: Tue, 23 Dec 2014 13:26:56 -0500
Message-ID: <00ac01d01ede$09469ce0$1bd3d6a0$>


And knowing which bits and where to optimize is all about understanding 1) orders of operations and 2) the difference between a human waiting for elapsed time to do the next thing and multiple machines kicking in each in turn. Which makes me think of Cary: profiling, so at least after the fact you get a clue about your orders of operation, and method-R, so you track response time when it is important.  


From: [] On Behalf Of Iggy Fernandez
Sent: Tuesday, December 23, 2014 11:52 AM To:; Oracle-L
Subject: RE: DWH varchar2(4000)  

The quote is about premature optimization.

"There is no doubt that the grail of efficiency leads to abuse. Programmers waste enormous amounts of time thinking about, or worrying about, the speed of noncritical parts of their programs, and these attempts at efficiency actually have a strong negative impact when debugging and maintenance are considered. We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil.  

Yet we should not pass up our opportunities in that critical 3 %. A good programmer will not be lulled into complacency by such reasoning, he will be wise to look carefully at the critical code; but only after that code has been identified. It is often a mistake to make a priori judgments about what parts of a program are really critical, since the universal experience of programmers who have been using measurement tools has been that their intuitive guesses fail. After working with such tools for seven years, I've become convinced that all compilers written from now on should be designed to provide all programmers with feedback indicating what parts of their programs are costing the most; indeed, this feedback should be supplied automatically unless it has been specificMly turned off."      

> Date: Tue, 23 Dec 2014 08:42:40 -0700
> From:
> To:
> Subject: RE: DWH varchar2(4000)
> We only have 3 sizes of VARCHAR2 1, 255, and 2000 (soon to be 4000). Does
not matter whether it is OLTP, hybrid or DW
> Doesn't Knuth have something to say about unnecessary optimization
> My job is not to make the duhvelopers job easier, it is to make the lives
of data entry clerks easier.
> Limiting the size of VARCHAR2 fields causes production outages. The same
way limiting the size of numeric fields does.
> Duhveloper: "We will never have over 1000000 rows"
> DBA: "Tell someone who cares. The field will be NUMBER(12,0)"
> 3 years later the table holds over 5 million rows.
> :)
> LF
> --
> Dave Morgan
> Senior Consultant, 1001111 Alberta Limited
> 403 399 2442
> --

Received on Tue Dec 23 2014 - 19:26:56 CET

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