oracle9i [message #334946] |
Fri, 18 July 2008 15:26 ![Go to next message Go to next message](/forum/theme/orafaq/images/down.png) |
shrinika
Messages: 306 Registered: April 2008
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Senior Member |
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Hello,
Why don't we declare max length(VARCHAR2(4000)) length for all string columns? Even if we store Hello, oracle would not allocate 4000. It allocate what we enter in the columns.
Tom has answered for this question.
http://tkyte.blogspot.com/2006/11/see-you-just-cannot-make-this-stuff-up.html
After reading the above link, i have one qestion on his below Tom's statement.
[B]Say the code prepares a query that selects ten columns
that are VARCHAR2. The developers, for performance, would like
to array fetch (very important). They would like to array fetch
say 100 rows (very typical). So, you have 4,000 * 10 * 100
= almost 4MB of RAM the developers must allocate! Now, consider
if that were ten VARCHAR2(80) fields (it’s probably much
smaller than that). That’s about 78KB. Ask the data modeler
how much RAM he is willing to kick in for this system [/B]
He is saying array fetch. Is this operating system specific or db specifc? Can we chane the array fetch? If so how do we change the array fetch? Any answer appreciated..
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Re: oracle9i [message #335043 is a reply to message #335034] |
Sun, 20 July 2008 00:55 ![Go to previous message Go to previous message](/forum/theme/orafaq/images/up.png) |
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Michel Cadot
Messages: 68678 Registered: March 2007 Location: Nanterre, France, http://...
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Senior Member Account Moderator |
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The answer is: it depends on the tools or language you use.
Regards
Michel
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