DNA sequence data - requirement for a long and wide table of experimental data
Is what you suggest a standard method of storing DNA sequencing results? Apart from the technical difficulties - good luck finding a database that will allow that many columns (SciDB?) - it will make querying tricky. I would look into ways of having your tables be tall and skinny rather than short and fat.

I would do something like the following: 

CREATE TABLE sample
(
  bed INTEGER NOT NULL,
  sample_no INTEGER NOT NULL,
  ..
  .. other fields? 
  .. chromosomal location? sequence? phenotype? 
  .. dna_type (gene | promoter | mRNA | tRNA... &amp;c.)?
  ..
  CONSTRAINT sample_pk PRIMARY KEY (bed, sample_no)
);


I believe that such a schema will facilitate querying and be far more technically feasible - it will conform far better to the relational model and will ultimately save you a lot of grief! I asked above Is this a standard method of storing DNA sequencing results? - this work has been done before so why are you reinventing the wheel? 

Don't get me wrong - I'm all in favour of experimenting and trying to get a new perspective on biological phenomena, that's what science/molecular biology is all about, but others must have done this before - you may want to look at their work? For the record, I have a Masters in Cellular and Molecular Genetics from the Univeristé de Paris. HTH...