[Info-vax] RDB Question

[Arne Vajhøj]

On 12/3/2018 9:50 PM, Kerry Main wrote:
>> From: Info-vax <info-vax-bounces at rbnsn.com> On Behalf Of Arne Vajhøj
>> Sent: December 3, 2018 3:17 PM
>> On 12/3/2018 12:41 AM, Phillip Helbig (undress to reply) wrote:
>>> In article <pu1po7$oh5$1 at gioia.aioe.org>, =?UTF-
>> 8?Q?Arne_Vajh=c3=b8j?=
>>> <arne at vajhoej.dk> writes:
>>>> Mimer if it still supports VMS.
>>>
>>> Not really an alternative to Rdb.
>>
>> Mimer is a relational database server.
>>
>> I think I looked a little into it 15-20 years ago, but I do not remember
>> anything.
>>
>> Any particular shortcomings compared to RDB.
> 
> Std question I always have for DB's on OpenVMS when comparing to Rdb - does
> the DB support active-active clustering?

Active/active is rarely a hard requirement.

If one look at Oracle and DB2 then even though they have RAC and
PureScale then only a small fraction actually use them.

> May of the popular DB's today like MySQL (if memory serves correctly) do not
> support active-active .. only the traditional active-passive mode.

MySQL can do active/active cluster, but it is using data replication
not shared storage.

> Also, Rdb supports row level locking which is a pretty big performance
> feature that some DB's do not support.

Row level locking is getting rather widely implemented these days.

The big commercial got it.

MySQL, Derby etc. got it.

> Not sure if Mimer supports either of these features.

Active/active probably not.

A quick google seems to indicate that Mimer is using
OCC (Optimistic Concurrency Control) similar to
GT.M and CouchDB.

Not sure what that really implies for suitability
in the context we are discussing.

Arne