How to calculate the row size

Question

Hi,
I am having a table of 4 column. First column is varchar2(10), Second column is Number(5), Third column is char(10) and Fourth column is Number(12,2).
Now how to calculate the size of each row. I want to know how much space it will take for each row.
Thanx & Regards,
Swarup

Answer 1

For a complete discussion of storage requirements for different datatypes see the Oracle 8i Concepts manual.
All Oracle documentation is available on-line via the 'Documentation' link on the OTN home page.
Your Col2 NUMBER(5) will take 4 bytes if it holds a 5 digit positive or negative number.
Your Col4 NUMBER(12,2) will take 7 bytes if it holds a number with 12 digits that is positive and will take 8 bytes if it holds a number with 12 digits that is negative.
The following is from the Concepts manual Chapter 12 (Copyright by Oracle)
Built-In Datatypes 12-9
Internal Numeric Format
Oracle stores numeric data in variable-length format. Each value is stored in
scientific notation, with one byte used to store the exponent and up to 20 bytes to
store the mantissa. The resulting value is limited to 38 digits of precision. Oracle
does not store leading and trailing zeros. For example, the number 412 is stored in a
format similar to 4.12 x 10 2 , with one byte used to store the exponent (2) and two
bytes used to store the three significant digits of the mantissa (4, 1, 2). Negative
numbers include the sign in their length.
Taking this into account, the column size in bytes for a particular numeric data
value NUMBER ( p), where p is the precision of a given value, can be calculated
using the following formula:
ROUND((length( p)+ s)/2))+1
where s equals zero if the number is positive and s equals 1 if the number is
negative.
Zero and positive and negative infinity (only generated on import from Version 5
Oracle databases) are stored using unique representations. Zero and negative
infinity each require one byte; positive infinity requires two bytes.
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