[Info-vax] OpenVMS x86-64 and RDB and DB's in general on OpenVMS

[Jan-Erik Soderholm]

Arne Vajhøj skrev den 2015-07-01 00:46:
> On 6/30/2015 3:55 PM, Jan-Erik Soderholm wrote:
>> JF Mezei skrev den 2015-06-30 21:12:
>>> On 15-06-30 09:08, clairgrant71 at gmail.com wrote:
>>>> Porting Oracle and Rdb to VMS are both huge, but very different,
>>>> undertakings.
>>>
>>> On the one hand, one is told that for most ports, it is just a matter of
>>> recompiling.  (I realise there is the cost/trouble of testing/validating
>>> etc).
>>>
>>> What sort of system features would Oracle and RDB use which are
>>> architecture specific and require much work to port from one 64 bit
>>> architecture to another on the same opertating system ?
>>
>> The specific architecture in itself!
>>
>> Today Rdb produces IA64 machine code on the fly (and before that
>> VAX and Alpha naitive machine code), and that will need to be
>> ported to X86 machine code. The same for the pre-compilers that
>> also compiles the SQL EXEC, END EXEC sections into machine code.
>
> The precompilers do not generate XXX source code that are sent
> through the XXX compiler??

No.
(Say) the precompiler for C, generates machine code (object
code) from the SQL statements, *not* C code!

The only C code the precompiler generates is the function
call to the generated machine object code. In the C code the
EXEC SQL/END EXEC block is replaced with a function call.

The list file from the precompiler contains the generated
machine code (formatted using assembly mnemonics together
with the rest of the C code as, well C code, with the EXEC
block commented and a function call inserted instead.

The rest of the file (the pure C code) is then sent throught
the standard C compiler and finaly the object code created
from the SQL statements are linked together to the object
code created by the standard C compiler into the EXE.

That is the same for all languages.

The runtime generation of machine code happens at, well, runtime. :-)



>
>> There is also a need for a supported X86 version of BLISS. The
>> lack of that made the "Rdb8 for NT" to be canceled. That is
>> probably also need for VMS in itself, anyway... :-)
>
> I would say so.
>
> Arne
>
>