Data type vs Storage

Question

Hi Guys,
lets say we have
TABLE1 (CHAR(1 BYTE))
TABLE2 (CHAR(1 CHAR))
The TABLE1 is clear, we store 20 records, it actual data will take up 20 bytes. What about the TABLE2?
Given the same data as TABLE1, will it still take up 20 bytes.
One thing for sure, if Multi Byte characters (UTF8 etc) are stored then obcviously it will take up more space :)
Thank you for your help.
Regards,
Faisal.

Answer 1

In general, the discussion of storage space is found in Chapter 2 of the SQL Reference manual. For 10gR2, you find that at http://download.oracle.com/docs/cd/B19306_01/server.102/b14200/sql_elements001.htm#i45441
WHen looking at UTF (8 or 16), a great extra reference is Chapter 6 of the Globalization Support Guide. Again for 10gR2 look http://download.oracle.com/docs/cd/B19306_01/server.102/b14225/ch6unicode.htm#sthref678
UTF is a standard and a lot of supporting information, including PDFs of all the characters, and how they are stored. can be found at http://www.unicode.org
In general, storing something at UTF8 will take 1,2,3 or 4 bytes (variable). UTF16 will take 2 or 4 bytes.
And anything stored in a multibyte CLOB will automatically be UCS-2 compatible regardless of your character set. http://download.oracle.com/docs/cd/B19306_01/server.102/b14225/ch6unicode.htm#i1007440