Row header

Data Modeling
Enthusiast

Row header

Can anyone please let me know if there are cases where row header overhead for MVC  can increase or expand the capacity or size?

Thanks and regards,

Raja

2 REPLIES
Teradata Employee

Re: Row header

Raja, are you asking if there are times when the use of MVC can produce a table space that is actually larger than the table without compression?  If so, the answer is "yes".  It generally occurs when the column being compressed is small in size and the number of values compressed are high.  Each compressed value requires a bit in the row header, so when the number of bytes required in the row header for compressed value bits exceeds the (average) size of the column being compressed then you wind up with a bigger row than you would have had otherwise.  You can avoid this by reducing the number of values compressed to eliminate the least frequently used values.

Enthusiast

Re: Row header

Hi Jake,

Thanks for a quick respone. Now if I have this table say 100000 records:

ct abc( id integer, dob date, sex char(1), status char(2), trans_date date)......

I want to know in Teradata 14, how  the table header will be and how the row header header will be?

sex is having values M,F and status is having values of  A to Z and a combination totalling to 255 distinct values.

So what is the suggestion for these cases?

Also I have chance of making this table as MLPPI.

How are the row headers and table headers be in terms of bytes?

Thanks and regards,

Raja