[Info-Ingres] non blocking sysmod

[Karl & Betty Schendel]

At 1:14 PM +0100 4/17/07, martin.bowes at ctsu.ox.ac.uk wrote:
>Hi Everyone,
>
>I seem to recall a rumour that sysmod would be altered so that with an
>appropriate flag it would not seek an exclusive database lock.
>


I don't know what current plans exist, if any.
The last time I remember it being talked about, the only way
anyone could think of to actually implement it was to do a trick
along the lines of what online checkpoint does at startup:
don't actually boot sessions, but stall new transactions and
wait for any existing transactions to end.  Then, run the
sysmod (keeping new transactions stalled until the core catalogs
are done), and release the block.

Only in this case it would have to be all transactions I think,
not just updating transactions.

(Problem is, DMF keeps the four core catalogs open at all times
when the database is open (ie sessions are connected), and you
can't modify the core catalogs while they are open.)

Anyway, I have no idea whether this is still the best idea
around, or if someone has come up with a better way since a
year ago.

Karl