Thread: Default numeric scale of zero in JDBC?

Hello,

I have discovered that the jdbc driver apparently uses a default scale of zero decimal places for SQL numeric
operators,including the sum() aggregate operator.  For example, this query: 

select (1.5 + 2);

This returns 4 from jdbc, but it returns 3.5 when run from within PGAdmin.  The only way I can coerce the value to
returndecimal places is to explicity cast the value to a numeric with scale: 

select cast(1.5 + 2 as numeric(10,2)) as value

This returns 3.5.

Also, queries like "select sum(value) from table" returns a rounded value, even though the column 'value' is
numeric(16,2). Is there a magic vmparam or setting to default the precision at the jdbc driver level?  I am trying to
runa large existing system on PostgreSQL and it is not feasible to hunt down all numeric operations in thousands of
classesto explicitly cast them.   Have others have encountered this issue? 

Thanks,

-Todd

Hello,

I downloaded the jdbc source and noted that if I specified a default scale of 4 in
AbstractJdbc2ResultSetMetadata.getScale()(if the column is numeric and the scale is -1), I received the desired
results. I further updated the code to provide a private DEFAULT_NUMERIC_PRECISION that defaults to 4, which can be
overriddenwith the System property org.postgresql.jdbc2.DEFAULT_NUMERIC_SCALE.  I built this and tested it within
SquirrelSQL and it works properly, and the system property is working to override this default.  Would this be an
updatethat the jdbc driver developers would be interested in? 

I suppose my other question is, what do other JDBC drivers default this to?  Also, does this imply that others do not
usenon-integer arithmetic with sql through JDBC? 

-Todd

----- Original Message ----
From: Todd Shoemaker <jtshoe11@yahoo.com>
To: pgsql-jdbc@postgresql.org
Sent: Thursday, January 18, 2007 8:05:42 AM
Subject: [JDBC] Default numeric scale of zero in JDBC?

Hello,

I have discovered that the jdbc driver apparently uses a default scale of zero decimal places for SQL numeric
operators,including the sum() aggregate operator.  For example, this query: 

select (1.5 + 2);

This returns 4 from jdbc, but it returns 3.5 when run from within PGAdmin.  The only way I can coerce the value to
returndecimal places is to explicity cast the value to a numeric with scale: 

select cast(1.5 + 2 as numeric(10,2)) as value

This returns 3.5.

Also, queries like "select sum(value) from table" returns a rounded value, even though the column 'value' is
numeric(16,2). Is there a magic vmparam or setting to default the precision at the jdbc driver level?  I am trying to
runa large existing system on PostgreSQL and it is not feasible to hunt down all numeric operations in thousands of
classesto explicitly cast them.   Have others have encountered this issue? 

Thanks,

-Todd






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Todd Shoemaker wrote:
> Hello,
>
> I downloaded the jdbc source and noted that if I specified a default scale of 4 in
AbstractJdbc2ResultSetMetadata.getScale()(if the column is numeric and the scale is -1), I received the desired
results. I further updated the code to provide a private DEFAULT_NUMERIC_PRECISION that defaults to 4, which can be
overriddenwith the System property org.postgresql.jdbc2.DEFAULT_NUMERIC_SCALE.  I built this and tested it within
SquirrelSQL and it works properly, and the system property is working to override this default.  Would this be an
updatethat the jdbc driver developers would be interested in? 
>
> I suppose my other question is, what do other JDBC drivers default this to?  Also, does this imply that others do not
usenon-integer arithmetic with sql through JDBC? 

Given that the reported metadata scale does not affect what the driver
does at all, and all the computation is done on the server side, I'd say
that any rounding that is happening is happening in whatever is using
the driver's metadata ("Squirrel SQL?")

-O