never knew the rows were stored in chain for more than 255 columns
Vijay, December 14, 2005 - 4:20 am UTC
Hi Tom,
good day to you, I knew the maximum number of columns for a table are 1000,but didn't know that if more than 255 columns are there in a table the rows are stored in chained way, I never came across a table having requirement of 255 or more columns so in case there's a requirement of more than 255 columns then will the chaining impact performance and why is the limit in chunks of 255, only just curious.
Kind Regards,
Vijay
December 14, 2005 - 8:32 am UTC
because 255 is the biggest number a byte can store.
the limit used to be 255.
rather than change the entire format of a block, they kept it at 255 - but allow for chaining of multiple pieces.
Single or Multiple table?
A reader, March 01, 2007 - 1:17 pm UTC
Hi Tom
I have some data in one of the existing table of 30 columns. As per the new requirement there are 15 more attributes added to it.
1. Most of the time these data are required by the clients separately
2.The newly added set of data is optional.
3. The newly added set is either present for all the rows or not present in any of the rows
Should I have a new table or add columns to the existing table?
March 02, 2007 - 12:53 pm UTC
#3 is very confusing
if it is present for all rows - it is not optional
if it is not present for any row - it is not there
Oracle 10g
Bibin, August 31, 2012 - 12:40 am UTC
What is the maximum number of tables we can created in oracle 10g ?
September 10, 2012 - 6:26 pm UTC
in theory, infinite.
in reality, your mind would be blown before you get to the limit.
it would be restricted only by the size of the system tablespace.
Thanks a lot
Vasant Chauhan, October 05, 2012 - 6:20 am UTC
Thank you so much.
I have added multiple columns as required by me......
Columns in a Table
Sana, June 05, 2013 - 12:00 pm UTC
what is maximum number of columns in Oracle 11G? What is the impact of Normalization in table creation when it goes beyond 255 columns? Jus for information Im asking this question. Any answers or suggestion will be appreciated.
June 05, 2013 - 2:26 pm UTC
1,000 is the documented maximum
http://docs.oracle.com/cd/E11882_01/server.112/e25513/limits003.htm ... hat is the impact of
Normalization in table creation when it goes beyond 255 columns? ....
same impact as when it goes beyond 5? I'm not sure what you are looking for here. What do you mean by "impact".
It would be rare to have a entity with hundreds of attributes, many times when I see that, i see attribute named "x_1, x_2, x_3, .... x_100" - meaning they are not normalizing...
Mastan, April 29, 2015 - 12:08 pm UTC
DECLARE
gtable varchar2(30):='&givtablename';
cnt number(38):=&numofcolumns;
BEGIN
execute immediate 'create table '||gtable||'(col1 number(2))';
for i in 2..cnt
LOOP
execute immediate 'alter table '||gtable||' add col'||i||' '||'number(2)';
END LOOP;
END;
Check above syntax and Run ,it let us know the limit of columns in a table
Mastan, April 29, 2015 - 12:10 pm UTC