Wastage space on Teradata database

Database

Wastage space on Teradata database

I have one database having 50GB space free. But, actual space left after considering skew factor is 20GB..so,here wastage space is 30GB..Also there are few tables which having high skew factor.. Can anyone please help me to understand the AMP distribution in this case?
2 REPLIES
Teradata Employee

Re: Wastage space on Teradata database

The thing you have to remember about space, is that even if you specify it at the Database level, it is given at the AMP level.

When a DB has XX GB of MaxPerm, in fact it's each AMP who have a (XX / NbAMP) of MaxPerm.

So yes, skewed tables have the downside of wasting space.

 

You should change the PI of your skewed tables if possible.

You can even try NO PRIMARY INDEX (NoPI) tables, it will be evently distributed, but of course you will have impacts on queries, so this is not something to do blindly.

 

Senior Apprentice

Re: Wastage space on Teradata database

To add one other thought to the good answer from @Waldar ...

 

A NOPI table will typically be evenly distributed if you load it with data from outside of the dbms platform (using tpt stream, load or single row inserts etc.)

 

But, if you load it using an insert/select then the data distribution of the NOPI table is determined by the data distribution of the final Spool file - which you have no direct control over. If this becomes a problem then use the 'hash by' clause on the insert/select.

 

Cheers,

Dave

 

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