Re: SET NOLOGGING in JDBC url?

On 18 ene, 22:04, Gerhard Hofmann <ghof050...@xxxxxxxxxxxxxx> wrote:
On 18 Jan., 21:17, "James Gramling" <jimwgraml...@xxxxxxxxx> wrote:



Does that "simple update" have a where clause? Unless the output is
truncated in IPM, that's what it looks like is running. If it doesn't have
a where clause, then that's an obvious cause for the slowness and it has
nothing to do with JDBC: the update is hitting all rows in the table. If
they are running this query in a loop, then it the application is
redundantly updating every row in the table over and over again!

It's right it does not have a where clause, the query *should* run
only once against the whole table but maybe it really is executed many
times. I have repeatedly executed refresh / SHIFT F3 in IPM and the
state of the query changed from DIOR to COM and back to DIOR and so
on. I'll ask the developer if (by accident...) the query may be run
multiple times.

Thanks + best regards
Gerhard


Hi Gerhard,

Just in case, in this tread
http://groups.google.es/group/comp.databases.ingres/browse_thread/thread/8c54352890abb229
you can see how to disable locks in the table iisynonym while you are
doing an jdbc statement with CA driver. I think this could be quite
obsolete now, but if it not, it could impact your statement while
others are running. This thread also talks about isolation scope
during trasactions which I think it is probably more important in your
case.

I do not see clearly the use (or meaning) of the statement you
mentioned. If I get it right this statement could have more that one
execution at a time (i.e two threads, or two sessions in parallel)? If
so, what do you want as result when two executions of the statement
are in the same moment, the second update should wait till the first
one finishes or not? if you want the former the whole table should be
locked (and it will -must- be slow). If not (it could be quite strange
without a where clause) you should look to fine grain the isolation of
the statement permiting the read/update of some rows while others are
still updating. This at first seems a bit nonsense (dirty reads and
all of that), but perhaps could be some reason for it (?). Anyway, the
isolation level could be the key in this case. Finally, remember that
the scope is intended for managing the isolation level of individual
transactions, you have to stablish it in every JDBC statement.

Hope this helps

Carlos
.

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