data_get precision loss for numbers with many digits

[acautin]

Using data_get after executing the following query results in loss of precision:
SELECT 2.700000000000005 FROM dual
Is returned as 2.70000000000001

I am not really convinced we are properly using the full precision of erlang as this is getting rounded even before the erlang precision is a problem.

Also maybe related: oracle/odpi#4

[acautin]

Question to odpi, ref: oracle/odpi#100 (comment)

[stoch]

@acautin Just a small remark:

Assuming that tools like TOAD are the norm, we have to be careful:

SELECT to_char(2.700000000000005) FROM dual
gives
TO_CHAR(2.700000000000005)

2.700000000000005
1 row selected.

whereas

SELECT 2.700000000000005 FROM dual
gives:
2.700000000000005

   2.70000000

1 row selected.

The inherent precision is conserved but the default rendering in TOAD (probably Oracle) does some default rounding to 8 digits.

SELECT 2.700100021200305 FROM dual
gives
2.700100021200305

   2.70010002

1 row selected.

[c-bik]

@acautin is oracle/odpi#100 (comment) good enough to close this issue?

[acautin]

@c-bik haven't tried it yet, as soon as I try it out (after finishing with edits) will confirm and close.