Shaun Forbes created EMPIREDB-208:
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Summary: Decimal fields don't support scales above 9
Key: EMPIREDB-208
URL: https://issues.apache.org/jira/browse/EMPIREDB-208
Project: Empire-DB
Issue Type: Bug
Components: Core
Reporter: Shaun Forbes
The code for determining a decimal/numeric columns scale from it's size is
assuming that 9 is the maximum value for the scale value, when in fact the
scale can be as large as the columns precision (up to 38 I believe).
Precision and scale for a decimal field is encoded in a double as
"precision.scale", so a numeric(10,3) field size is encoded as the double value
10.3.
numeric(17,12) is also a valid numeric field, but because the code assumes that
the scale is less than 10 this causes problem, even if it's stored as 17.12 in
the columns size field.
Even worse would be numeric(17,10), which would be interpreted as having a
scale of 1 rather than 10.
The manifests itself in 2 location, that I've found so far, when validating a
decimal field and when generating a DDL statement.
The offending code in DBTableColumn.validateNumber(DataType type, Number n) is:
{code}
int reqScale =((int)(size*10)-(reqPrec*10))
{code}
and in DBDDLGenerator.appendColumnDataType(DataType type, double size,
DBTableColumn c, StringBuilder sql) is:
{code}
int scale = (int) ((size - prec) * 10 + 0.5);
{code}
By first suggestion for a fix would be to alter the 2 pieces of code above to
perform the correct conversions from double to precision/scale, using something
like BigDecimal, but the problem is by then it's too late, numeric(17,12) would
be fine, but it would not fix the problem for numeric(17,10) as it would
already be stored as 17.1 in the column size.
I don't see any option but to either move the scale into a separate value and
stop encoding it in the size, or change the column size field to be a
BigDecimal (or some other value that can represent both the precision and scale
correctly).
The former feels more correct to me, but the later would seem easier to
implement, unfortunately both of those options are API breaking changes.
Thanks,
Shaun
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