Re: [Tarantool-patches] [PATCH v2 1/1] sql: make NUMBER to be union of SQL numeric types

[Mergen Imeev <imeevma@tarantool.org>]

Hi! Thank you for review. My answer and new commit-message
below.

On Mon, Jan 13, 2020 at 03:58:29PM +0300, Nikita Pettik wrote:
> On 31 Dec 12:46, Mergen Imeev wrote:
> > Hi! Thank you for review. My answer below.
> > 
> > On Tue, Dec 31, 2019 at 10:56:07AM +0200, Nikita Pettik wrote:
> > > On 31 Dec 11:50, imeevma@tarantool.org wrote:
> > > > This patch makes number to be union of UNSIGNED, INTEGER and
> > > > DOUBLE numeric types.
> > > > 
> > > > Closes #4233
> > > > Closes #4463
> > > 
> > > Please, explain in details changes in explicit/implicit
> > > casts behaviour.
> > > 
> > Fixed:
> > 
> > commit 492646da4f781b863e5e3e488a0be53f31d28964
> > Author: Mergen Imeev <imeevma@gmail.com>
> > Date:   Sat Oct 26 17:27:53 2019 +0300
> > 
> >     sql: make NUMBER to be union of SQL numeric types
> >     
> >     This patch makes number to be union of UNSIGNED, INTEGER and
> >     DOUBLE numeric types.
> >     
> >     Closes #4233
> >     Closes #4463
> >     
> >     @TarantoolBot document
> >     Title: NUMBER type in SQL.
> 
> Could you please intead of 3 paragraphs just include following
> changelog list:
> 
> "This patch makes definition of NUMBER type be consistent with NoSQL.
>  Previously (for historic reasons) in half-cases NUMBER served as a
>  synonym of DOUBLE type.
>  After patch is applied following will change:
>  - CAST AS NUMBER operation no more longer results in any value
>    change in case value is already of numeric type. Example:
>    Obsolete behaviour:
> 	SELECT CAST(922337206854774800 AS NUMBER);
>         Result: 9223372036854774784
>    New behaviour:
>         SELECT CAST(922337206854774800 AS NUMBER);                              
>         Result: 9223372036854774800LL
>  - ...
> "
> 
> Or group implicit/explicit cast changes. Text below is quite
> compicated to perceive (IMHO).
> 
I removed the part that describes the cast from STRING and
VARBINARY to NUMBER, since I'm not sure if this is the
correct behavior. I think it will be fixed in #3809 and
#4230 issues:
https://github.com/tarantool/tarantool/issues/3809
https://github.com/tarantool/tarantool/issues/4230

> >     
> >     The NUMBER type in SQL is the union of all currently available
> >     numeric types in SQL: INTEGER, UNSIGNED, and DOUBLE. The types
> >     INTEGER and DOUBLE can be called subtypes of type NUMBER. Any
> >     value of type NUMBER has a subtype of INTEGER or DOUBLE. When
> >     any numeric value is implicitly or explicitly casted to NUMBER,
> >     the only thing that can change is its type. Its type will become
> >     NUMBER. When a value of type NUMBER is cast explicitly or
> >     implicitly to other numeric types, the rules applicable to the
> >     cast are determined by the subtype of the value.
> >     
> >     If a value of type STRING can be implicitly cast to value of
> >     type INTEGER or DOUBLE, then this value can be cast explicitly
> >     and implicitly to a value of type NUMBER. If this value can be
> >     implicitly cast to INTEGER, then its subtype will be INTEGER.
> >     The subtype will be DOUBLE in another case.
> >     
> >     If a value of type VARBINARY can be explicitly cast to type
> >     INTEGER or DOUBLE, then this value can be explicitly cast to a
> >     value of type NUMBER. If this value can be explicitly cast to
> >     INTEGER, then its subtype will be INTEGER. The subtype will be
> >     DOUBLE in another case.
> > > > ---

New commit-message:

commit ac5e4fcffe17767efa7da77427024e2d679bebf7
Author: Mergen Imeev <imeevma@gmail.com>
Date:   Sat Oct 26 17:27:53 2019 +0300

    sql: make NUMBER to be union of SQL numeric types
    
    This patch makes definition of NUMBER type be consistent with
    NoSQL. Previously (for historic reasons) in half-cases NUMBER
    served as a synonym of DOUBLE type.
    
    After patch is applied CAST AS NUMBER operation no more longer
    results in any value change in case value is already of numeric
    type.
    
    Example:
    Obsolete behaviour:
    	SELECT CAST(922337206854774800 AS NUMBER);
    	Result: 9223372036854774784
    New behaviour:
    	SELECT CAST(922337206854774800 AS NUMBER);
    	Result: 9223372036854774800LL
    
    Closes #4233
    Closes #4463