SQL error: BCD overflow caused by too many coalesce - sql

Question

To eliminate null values from fields for some reason the use of too many coalesce results in BCD Overflow errors
I eliminated the error to 1 line in the select part.
If any (of the 4) coalesces are replaced by a fixed value it's ok
If any coalesce is removed, the result is also ok
If for any field another is used, the error remains
Replacing the '/' with '-' also gives a result but not the correct value.
All fields are numeric(10,4).
It's Firebird version 2.5.8
select
coalesce(Field1, 0) * coalesce(Field2, 0) * ((100 - coalesce(Field3, 0)) / 100) * ((100 + coalesce(Field4, 0)) / 100)
from Table
A calculated column is expected, the actual result is a BCD overflow

Answer 1

Not quite an answer, just a test.
Firebird 2.1.7, IBExpert, SQL Dialect 3
create table t58096187 (
f1 numeric(10,4),
f2 numeric(10,4),
f3 numeric(10,4),
f4 numeric(10,4)
);
insert into t58096187 values ( 50, 50, 50, 50 );
select
coalesce(F1, 0) * coalesce(F2, 0) * ((100 - coalesce(F3, 0)) / 100) * ((100 + coalesce(F4, 0)) / 100)
from t58096187;
ERROR: Unsuccesful execution ... integer overflow ... cause the most significant bit of the result to carry
•Dialect 3 databases allow numbers (DECIMAL and NUMERIC data types) to be stored as INT64 when the precision is greater than 9
https://firebirdsql.org/manual/gfix-dialect.html
https://firebirdsql.org/file/documentation/reference_manuals/fblangref25-en/html/fblangref25-datatypes-fixedtypes.html
Same error with Numeric(9,4) which should avoid use if int64 internal datatype.
If I declare fields as float though, the select yields result 1875, which is well within Numeric(10,4) datatype.
Maybe some INTERMEDIATE result in reverse-polish goes out of bounds?
This also works if to avoid use of INT64 using
recreate table t58096187 (
f1 numeric(6,2),
f2 numeric(6,2),
f3 numeric(6,2),
f4 numeric(6,2)
)
It seems Firebird 3.0.5 is also affected - https://dbfiddle.uk/?rdbms=firebird_3.0&fiddle=57729b31e0a5019aea68a136638d9f50
There is no error - but no results either!
Numeric-as-Int32 works: https://dbfiddle.uk/?rdbms=firebird_3.0&fiddle=c4a4230e855b0ce4fd2b0c7b3b697cda
Reported as https://www.sql.ru/forum/1317439-a/
Mark's assumption of fractional part accuracy as causing this is probably correct.
recreate table t58096187 (
f1 numeric(10,4),
f2 numeric(10,4),
f3 numeric(10,4),
f4 numeric(10,3)
)
Still works.
https://dbfiddle.uk/?rdbms=firebird_3.0&fiddle=29a6c15d6e1854be230d29aea30307cf
Coalesce seems to have nothing with this my problem, dunno if it is relevant to the topic starter's problem, as it is ambiguous what he meant by "removing coalesce". After I removed coalesce it becomes like that
select
F1 * F2 * F3 * F4
from t58096187
And likely the same error
https://dbfiddle.uk/?rdbms=firebird_3.0&fiddle=1f29aff4102ace57e8fa27d83e59b93f

Answer 2

Apparently the problem is a little more specific: The result of an integer operation caused the most significant bit of the result to carry.
So applying the suggested solution (define the format for the resulting number we want to use) we would do:
select
cast( (cast(coalesce(f1, 0) as numeric(10,4)) * cast(coalesce(f2, 0) as numeric(10,4)) ) as numeric(10,4)) * cast(((100 - coalesce(f3, 0)) / 100) as numeric(10,4)) * cast(((100 + coalesce(f4, 0)) / 100) as numeric(10,4))
-- cast(coalesce(f1, 0) as numeric(10,4)) * cast(coalesce(f2, 0) as numeric(10,4)) * cast(((100 - coalesce(f3, 0)) / 100) as numeric(10,4)) * cast(((100 + coalesce(f4, 0)) / 100) as numeric(10,4)) -- sigue dando el mismo error
-- coalesce(F1, 0) * coalesce(F2, 0) * ((100 - coalesce(F3, 0)) / 100) * ((100 + coalesce(F4, 0)) / 100)
from t58096187;
Thanks to Arioch 'The for the great analysis and example to reproduce the error!