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DECFLOAT should not throw exceptions when +/-NaN, +/-sNaN and +/-Infinity is used in comparisons [CORE5699] #5965

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firebird-issue-importer opened this issue Jan 7, 2018 · 10 comments

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@firebird-issue-importer firebird-issue-importer commented Jan 7, 2018

Submitted by: @mrotteveel

Replaces CORE5698

The datatype DECFLOAT currently supports storing +/-NaN, +/-sNaN and +/-Infinity (because the underlying Decimal64 / Decimal128 supports that), this should be disallowed and when attempting to store these values, a "data exception — numeric value out of range" error (or equivalent) should be raised. Storing these values can be achieved by either storing it using parameters, or using conversion from string.

See also SQL:2016, 6.29 <numeric value expression>.

Currently Firebird already disallows overflow to +/- Infinity during calculations with DECFLOAT, nor is it (or should it be possible) to produce NaN during calculation.

Currently, storing +/-NaN or +/-sNaN in a column can lead to problems, for example in a select with a condition involving a decfloat column, having a NaN in that column leads to an error during fetch:

====
*** IBPP::SQLException ***
Context: Statement::Fetch
Message: isc_dsql_fetch failed.

SQL Message : -901
Unsuccessful execution caused by system error that does not preclude successful execution of subsequent statements

Engine Code : 335545141
Engine Message :
Decimal float invalid operation. An indeterminant error occurred during an operation.

Commits: d0d92de

====== Test Details ======

See functional\datatypes\decfloat-nan-and-infinity-comparison.fbt

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@firebird-issue-importer firebird-issue-importer commented Feb 2, 2018

Modified by: @AlexPeshkoff

Link: This issue replaces CORE5698 [ CORE5698 ]

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@firebird-issue-importer firebird-issue-importer commented Feb 2, 2018

Modified by: @AlexPeshkoff

assignee: Alexander Peshkov [ alexpeshkoff ]

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@firebird-issue-importer firebird-issue-importer commented Mar 22, 2018

Commented by: @AlexPeshkoff

Making it impossible to store special decimal float values in a field does not look like good idea. We can store such values in double field:
SQL> show table dou;
V DOUBLE PRECISION Nullable
SQL> select * from dou;

                  V 

=======================
0.5000000000000000
Infinity
NaN

(I've used c++ program to add such records to the table - insert with parameter.)
What should better be fixed is use of such values in comparison operators - with double precision values that works somehow:

SQL> select v, v < 1 from dou;

                  V         

======================= =======
0.5000000000000000 <true>
Infinity <false>
NaN <true>

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@firebird-issue-importer firebird-issue-importer commented Mar 22, 2018

Commented by: @mrotteveel

That could also work.

As far as I can tell from the SQL standard, technically double precision shouldn't support NaN and infinities either, but as we already do that, we could extend that to DECFLOAT as well.

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@firebird-issue-importer firebird-issue-importer commented Mar 23, 2018

Modified by: @AlexPeshkoff

summary: DECFLOAT should disallow +/-NaN, +/-sNaN and +/-Infinity => DECFLOAT should not through exceptions when +/-NaN, +/-sNaN and +/-Infinity is used in comparisons

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@firebird-issue-importer firebird-issue-importer commented Mar 23, 2018

Modified by: @AlexPeshkoff

status: Open [ 1 ] => Resolved [ 5 ]

resolution: Fixed [ 1 ]

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@firebird-issue-importer firebird-issue-importer commented Mar 23, 2018

Modified by: @mrotteveel

summary: DECFLOAT should not through exceptions when +/-NaN, +/-sNaN and +/-Infinity is used in comparisons => DECFLOAT should not throw exceptions when +/-NaN, +/-sNaN and +/-Infinity is used in comparisons

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@firebird-issue-importer firebird-issue-importer commented Mar 23, 2018

Modified by: @AlexPeshkoff

Fix Version: 4.0 Beta 1 [ 10750 ]

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@firebird-issue-importer firebird-issue-importer commented Mar 25, 2018

Modified by: @pavel-zotov

status: Resolved [ 5 ] => Resolved [ 5 ]

QA Status: No test => Covered by another test(s)

Test Details: See functional\datatypes\decfloat-nan-and-infinity-comparison.fbt

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@firebird-issue-importer firebird-issue-importer commented Mar 25, 2018

Modified by: @pavel-zotov

status: Resolved [ 5 ] => Closed [ 6 ]

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