SQL Anywhere database replication - Permanent passthrough mode

Author

Permanent passthrough mode

Pavel Karady

2006-01-30, 7:23 am

Taking advice for starting a new thread with this:

ASA 9.0.2.2551

The PASSTHROUGH statement was tested and it does exactly what we wanted to
achieve. But here's the shock (at least for us): it's connection dependent.
Thus, this renders it unusable for us.

If there could be a way, how to ensure that every connection, even through
dbisqlc only, has the PASSTHROUGH as the first statement processed, it would
be fine (1). Or, having a dbremote agent with a passthrough switch would be
fine (2).

If (1) is possible, then (2) is not necessary. Is there any way?

Thanks - thanks
Pavel

Rob Waywell

2006-01-30, 9:24 am

Yes the PASSTHROUGH state applies to a specific connection. I always
recommend that any passthrough changes be executed from scripts rather than
from Sybase Central. The important benefit of using scripts is that the
script can be written, tested, debugged, re-tested and verified on the test
system then taken and run on the production system. In contrast, any changes
done through Sybase Central rely on a human to manually execute the correct
steps and this is not sufficiently reliable for a production system.

Assuming that you are making your PASSTHROUGH changes using scripts, then it
is certainly possible for the appropriate line of the script to be
"PASSTHROUGH FOR ..."

--
-----------------------------------------------
Robert Waywell
Sybase Adaptive Server Anywhere Developer - Version 8
Sybase Certified Professional

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"Pavel Karady" <pavel_ns. ns_karady@ns_kogerus
a.com> wrote in message
news:43ddfdfe@forums
-2-dub...
> Taking advice for starting a new thread with this:
>
> ASA 9.0.2.2551
>
> The PASSTHROUGH statement was tested and it does exactly what we wanted to
> achieve. But here's the shock (at least for us): it's connection
> dependent.
> Thus, this renders it unusable for us.
>
> If there could be a way, how to ensure that every connection, even through
> dbisqlc only, has the PASSTHROUGH as the first statement processed, it
> would
> be fine (1). Or, having a dbremote agent with a passthrough switch would
> be
> fine (2).
>
> If (1) is possible, then (2) is not necessary. Is there any way?
>
> Thanks - thanks
> Pavel
>

Reg Domaratzki \(iAnywhere Solutions\)

2006-01-30, 11:24 am

Passthrough mode was designed in order to allow administrators at the
consolidated database to perform routine administration from time to time at
the remote sites. IMHO, running every connection in passthrough is using
SQL Remote in a method for which is was not intended, and you'll get
yourself into trouble.

Passthrough has to be connection dependant. Image an administrator running
a script that adds some new database users to the remote databases. Should
other connections that are modifying data at the same time as the
passthrough session also have their data executed in passthrough mode?
Absolutely not. If you forget to end you passthrough session (or the DB
crashes during a passthrough session), should the fact that the passthrough
was never specifically halted mean that everything you execute from now on
also be passed down in passthrough mode? No way.

IMHO, you're trying to fit a square peg into a round hole by having SQL
Remote execute everything in passthrough. Although you could probably find
a way to get the peg to fit eventually, it's going to make a lot of rattling
noises going through the hole. If you execute an single update statement
that modifies 1000 rows, SQL Remote will send 1000 updates. I think it's
better for you to live with that than try to use PASSTHROUGH mode for
something it was not intended for.

Having said all that, and going against every fiber in my body, I might
suggest you look into the login_procedure if you want to make every
connection execute in passthrough. You are destroying SQL Remote's conflict
resolution mechanism, and I have no idea what the effects of having the SQL
Remote connections to the database run in passthrough mode would be, as this
is something we would never test.
--
Reg Domaratzki, Sybase iAnywhere Solutions
Sybase Certified Professional - Sybase ASA Developer Version 8
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"Pavel Karady" <pavel_ns. ns_karady@ns_kogerus
a.com> wrote in message
news:43ddfdfe@forums
-2-dub...
> Taking advice for starting a new thread with this:
>
> ASA 9.0.2.2551
>
> The PASSTHROUGH statement was tested and it does exactly what we wanted to
> achieve. But here's the shock (at least for us): it's connection
dependent.
> Thus, this renders it unusable for us.
>
> If there could be a way, how to ensure that every connection, even through
> dbisqlc only, has the PASSTHROUGH as the first statement processed, it
would

> be fine (1). Or, having a dbremote agent with a passthrough switch would
be
> fine (2).
>
> If (1) is possible, then (2) is not necessary. Is there any way?
>
> Thanks - thanks
> Pavel
>
>

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