No Primary Index - skewing

Database

No Primary Index - skewing

Hi,  I have a table with approx 65,000 rows in, which I have defined as having "NO PRIMARY INDEX".  As far as I understood, such tables shouldn't skew, but I am calculating the skew at 86.91%.  The skew calculation I'm using is one I got from these forums which is roughly defined as avg(currentperm)/max(currentperm) * 100.  Is it possible for tables with no primary index to skew then?

3 REPLIES

Re: No Primary Index - skewing

For information, I have loaded this data using TPT.  I have tried loading the same data into new empty tables with the same structure, and the skew is still high but changes each time - 59.44%, 64.49%, etc...

Teradata Employee

Re: No Primary Index - skewing

A table that small will always be skewed. We round robin at the block level not the row level. A small number of amps will receive blocks and the rest will receive no data. Any table with less data than will require several blocks per AMP should be excluded from concern about skew. 

Re: No Primary Index - skewing

Thank you, I've learnt something ;-)  It seems that this behaviour can be flexed within TPT by specifying smaller BufferSize, but as you say, if this is only a problem with small tables, then I'm happy