I've found the decimal numbers to be most generally useful in narrow
ranges. For reference, here are a couple notes on how other databases
implement them:
MSSQL stores up to 38 digits in 17 bytes, with a specific precision.
http://msdn.microsoft.com/en-us/library/aa258832(v=sql.80).aspx
PostgreSQL is more flexible and supports up to 1000 digits.
http://www.postgresql.org/docs/current/static/datatype-numeric.html#DATATYPE-NUMERIC-DECIMAL
In order to get a jump on the implementation, I would suggest that it
might be possible to use C routines from the PostgreSQL project or
some appropriately licensed library. Perhaps an author from a numeric
library would be willing to donate their work to the SQLite project.
Patrick Earl
On Sat, Mar 26, 2011 at 7:43 PM, Simon Slavin <slav...@bigfraud.org> wrote:
>
> On 27 Mar 2011, at 2:39am, Patrick Earl wrote:
>
>> Base-10 numbers are frequently used in financial calculations because
>> of their exact nature. SQLite forces us to store decimal numbers as
>> text to ensure precision is not lost. Unfortunately, this prevents
>> even simple operations such as retrieving all rows where an employee's
>> salary is greater than '100' (coded as a string since decimal types
>> are stored as strings).
>>
>> I would like to encourage the developers to consider adding support
>> for base-10 numbers. This is clearly a very pertinent issue, as even
>> this month there was another thread regarding decimal support.
>
> Intersting idea. You will need to develop your own C routines to do
> calculations with decimals. Do you feel they should be implemented at a
> fixed length or would you want to be able to use decimal strings of arbitrary
> lengths ?
>
> Simon.
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