fix csv precision

[cmcarthur]

dbt 0.9.2 RC had a bug where we miscalculate the precision required for decimal values like 0.001. we were attempting to create a numeric(1,3) which doesn't make sense -- according to the Postgres docs:

NUMERIC(precision, scale)
The scale of a numeric is the count of decimal digits in the fractional part, to the right of the decimal point. The precision of a numeric is the total count of significant digits in the whole number, that is, the number of digits to both sides of the decimal point. So the number 23.5141 has a precision of 6 and a scale of 4. Integers can be considered to have a scale of zero.

So the precision should be 4, not 1. This branch fixes that.

[cmcarthur]

Used the file in #683 to test, also wrote unit tests for that max_digits fn

[drewbanin]

@cmcarthur lgtm! Nice job on that test

[joevandyk]

is this needed?

[joevandyk]

not a fan of that code climate "duplicate code" check that's currently failing btw. duplicate code is not always bad, trying to solve it often makes for more complicated code.

[drewbanin]

right there with you @joevandyk -- sometimes no abstraction is better than a bad abstraction

[joevandyk]

I confirmed this fixed my issue with loading the csv file. I think getting rid of the datatype limits is a good idea, as it allows for the truncate/insert strategy with different lengths of data.

[drewbanin]

lgtm!