[Info-vax] The best VMS features, was: Re: openvms renaming file

[Craig A. Berry]

On 5/28/18 2:58 PM, Arne Vajhøj wrote:
> On 5/28/2018 3:17 PM, seasoned_geek wrote:
>> On Monday, May 28, 2018 at 1:31:49 PM UTC-5, Arne Vajhøj wrote:
>>> On 5/28/2018 11:01 AM, Dave Froble wrote:
>>>>>
>>>>> But maybe great for replacing index-sequential files.
>>>>
>>>> I don't think so.  RMS indexed files allow concurrent use, using the 
>>>> DLM.
>>>
>>> You are right.
>>>
>>> SQLite will only replace let us say the low-end of index-sequential
>>> files usage.
>>
>> That is making the grand assumption that SQLite on VMS wouldn't integrate
>> DLM support.
> 
> That would be a major rewrite of SQLite. Not realistic.

Have a look at the port here:

<https://sourceforge.net/projects/vms-ports/files/SQLITE3/>

In particular note the file called "sqlite3_prv_lock.dcl" the header of
which starts with:

$!							1.5, 30-SEP-2015
$! Build the sqlite_prv_lock proteced shareable image to support 
implementing
$! the SQLITE3 database locking model with distributed lock manager locks.
$! The protected image provides exec mode system services to create system
$! locks associated with files open by the caller via SYS$OPEN().
$!

I have not delved deeply enough to see if it provides more granular
locking than is available on other platforms, but it does provide an
option to use the DLM.