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maximum columns in a table

Posted on 2002-07-03
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Last Modified: 2012-06-27
1) How many columns can we include in a create table statement.
2)Does it depend on data types and sizes of the columns.
3) Is there a concept called page size in oracle. If so, what is it?

--- k_murli_krishna
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Question by:k_murli_krishna
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pennnn earned 300 total points
ID: 7127483
1)1000
2)Yes - if it's an object table (see details below)
3) I'm not aware of such a concept. Which doesn't mean that it doesn't exist...
The same question was asked a few days ago:
http://www.experts-exchange.com/oracle/Q_20317109.html
Here's what I posted there:
From the SQL Reference:
"The absolute maximum number of columns in a table is 1000. However, when you create an object table (or a relational table with columns of object, nested table, varray, or REF type), Oracle maps the columns of the user-defined types to relational columns, creating in effect "hidden columns" that count toward the 1000-column limit. For details on how Oracle calculates the total number of columns in such a table, please refer to Oracle8i
Administrator’s Guide."
The same is valid for a view:
"The subquery’s select list can contain up to 1000 expressions."
Hope that helps!
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by:Mark Geerlings
ID: 7127500
1. That depends on your version of Oracle, the limits are higher in the higher versions.  I have never come close to the limit of columns in a table, so I don't pay much attention to the actual limit in each version.

2. No, unless you use some of the newer object types or user-defined types, but if you do use these then yes, because Oracle will then automatically create some additional hidden columns that must be included in the total number of columns.

3. No, not as far as I know.  Oracle stores data in blocks.  These are grouped into extents and segments.  Thay are contained in datafiles and tablespaces.
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Expert Comment

by:asimkovsky
ID: 7129137
The concept of a "page size" is relevant to SQL Server, but it is basically the same concept of datablocks in Oracle. Oracle calls them datablocks, and SQL Server calls them pages.


Andrew

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