To summarize the proposed change:
The SQL_DEC_FIXED type is dropped in favour of using SQL_DEC34 with
subtypes, and I assume this to also mean the blr_dec_fixed is removed,
including the need to send the scale separately in the request BLR.
As a result, SQL_DEC34 will represent:
DECFLOAT with subtype = 0
NUMERIC(p > 18) with subtype = 1
DECIMAL(p > 18) with subtype = 2
For subtypes 1 and 2, isc_info_sql_scale (and XSQLVAR.sqlscale and
equivalent in new API) will report the defined scale of the column or
parameter. For subtype 0 (decfloat), it will always report scale as 0.
Open issues
===========
1. When sending values from client to server, will Firebird reject
values with the wrong scale for subtypes 1 and 2, or round them to the
correct scale?
As an example, will sending 12.345 (12345e-3) for a DECIMAL(34,2) be
rejected with an incorrect scale error, or will it be rounded
appropriately (to 12.34 (1234e-2) assuming half even rounding)? Similar
sending 123 (123e0) will that throw an error, or 'round' to 123.00
(12300e-2)?
If the second option, errors would only be raised if this would produce
an overflow (eg sending 123e34 can never be made to fit a decimal(34,2))
If we follow the SQL rules for store and retrieval assignment (9.1 and
9.2), then we should allow values with a different scale, and round
appropriately.
But would this lead to differences in behavior compared to DECIMAL and
NUMERIC with precision <= 18? I'm not sure if it is currently possible
to send 12345 with sqlscale = -3 and have it converted correctly to a
scale 2, or not. I can experiment with Jaybird to check, but if someone
knows that would save me some time (as Jaybird itself already rounds
before sending, and circumventing that is a bit of a pain).
Am I missing anything else?
Mark
--
Mark Rotteveel
------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
Firebird-Devel mailing list, web interface at
https://lists.sourceforge.net/lists/listinfo/firebird-devel
