[Info-vax] CRTL and RMS vs SSIO

[Arne Vajhøj]

On 10/6/2021 9:25 PM, Greg Tinkler wrote:
> What a good conversation, some feedback.
>> To be honest then I think the safest way to implement this is
>> to put lots of restrictions on when it is doable.
>>
>> Examples:
>> * No cluster support (announcement already states that!)
>> * Only FIX 512, STMLF and UDF are supported
>> * no mixing with traditional RMS calls
> 
> My point is SSIO seems to be focused on just PostgreSQL, whereas an
> RMS solution is much much easier to program, uses well tested code,
> and is already cluster ready putting the team ahead of the game and
> not building issues for the future.
I very much doubt that  a full RMS solution is much easier.

:-)

>> For this case, RMS really doesn't work at all well. Says why right
>> there in the name, too. Record management, not stream management.
> 
> Well yes and no.  If you think about it most Unix text IO is record,
> ie LF terminated, and binary is fixed records not necessarily the
> same length in the file.
> 
> RMS for $GET and $PUT are record based, but $READ and $WRITE are
> block based, missing is $READB and $WRITEB, not just for CRTL but
> useful for various applications.
> 
> RMS ISAM with fixed length records is a pain, I have long argued ISAM
> should support variable length records, don’t care if they are VFC or
> STMLF, I would allow for both as VFC could allow for binary variable
> length records.
????

Index-sequential files and RMS API supports variable length.

Not all language API's on top of RMS does.

>> The use of Oracle Rdb isn't viable as a dependency for many folks, and
>> lock granularity doesn't work at all well for arbitrary and overlapping
>> locking ranges.

> I think you will be a B-Tree style dynamic resource tree, similar to
> what Rdb uses, will work well.  Any ‘byte range’ implementation will
> need some index to find interesting locks, DLM uses hash which is as
> efficient as you can get.
Hash is effective for finding exact matches but useless for finding
other matches aka "starting with". For those a tree is better.

Arne