RE: DWH varchar2(4000)

From: Kenneth Naim <>
Date: Mon, 22 Dec 2014 10:50:10 -0500
Message-ID: <009001d01dfe$f89ef4d0$e9dcde70$>

I agree with you, it is a waste and it leads to many issues. It is standard warehouse practice to increase the size of the column to allow for future grow from the source system but it should be reasonable (50-100% larger). A 200 byte column from the source system should be created as 300 or 400 bytes not 4000 bytes, and a 10 byte column no more than 20 bytes.  


From: [] On Behalf Of Ricard Martinez Sent: Monday, December 22, 2014 10:02 AM To:
Subject: DWH varchar2(4000)  

Hi list,  

We have a DWH database on

The developers/data modelers are creating all the tables with varchar2(4000) as standard by default. They don't care if they just insert 10 bytes, 200 or nothing.

When asked about why this standard is in place, the answer is just: "Just in case we need it".  

For my point of view this is not a good practice, as can cause memory waste on client applications, as well as data garbage or errors like ORA-01450: maximum key length (3218) exceeded.  

But as i'm not a DWH expert, maybe im missing information that proves that this is really a good practice, and not just a laziness way of working.  

I will be glad to know your opinion, or point me to any doc/test that proves me wrong, in order to learn about this.  


Received on Mon Dec 22 2014 - 16:50:10 CET

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