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Physical sizes of data types

Can you tell me the physical size of the data types, including as Date, Number, VARCHAR2? How about physical size...

of an index? Does each index have a ROWID also? Or is ROWID only for the table? I need this information so that I can calculate the size of physical record space occupied.

Oracle sizing can be quite complex. In fact, they have even removed this information from many of the manuals. Generally numeric data is n/2+1 where n is the physical size. Dates are 8 bytes (7 bytes plus a header byte) varchar2 are the actual length plus a header byte, except if you exceed 255 long then they are 2 header bytes, blob, clob are special cases. Char are always the full length specified plus a header byte (they are blank padded).

Indexes are tricky since they store rowid as well as the index data. E-mail me at mike@ault.cc, and I can get you some spreadsheets for sizing.


This was last published in July 2004

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