Subject | RE: [firebird-support] Re: Performance when deleting a lot of records, again |
---|---|
Author | Gili Buzaglo |
Post date | 2005-04-07T14:43:04Z |
Can this be the reason:
I have the following scenarion:
1) A connection is open and I have read query run on it.
2) I perform a write query through another connection.
3) I commit the write query
4)I close the statement of the read query.
Can it be because step 3 is before step 4 ?
Thanks
-gili
-----Original Message-----
From: Ann W. Harrison [mailto:aharrison@...]
Sent: Thursday, April 07, 2005 5:33 PM
To: firebird-support@yahoogroups.com
Subject: Re: [firebird-support] Re: Performance when deleting a lot of records, again
Daniel Rail wrote:
record versions that are visible to active transactions. The problem is
a long-lived snapshot transaction.
doesn't have to have touched the two bad tables. Remember, a snapshot
is a stable view of the database, not just a particular table. That's
important for consistency in many cases. Consider the case of two
tables, credits and debits. If you read credits before another
transaction makes a credit/debit adjustment, then read debits, you must
read the debit table in the state it was in before the change.
Regards,
Ann
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I have the following scenarion:
1) A connection is open and I have read query run on it.
2) I perform a write query through another connection.
3) I commit the write query
4)I close the statement of the read query.
Can it be because step 3 is before step 4 ?
Thanks
-gili
-----Original Message-----
From: Ann W. Harrison [mailto:aharrison@...]
Sent: Thursday, April 07, 2005 5:33 PM
To: firebird-support@yahoogroups.com
Subject: Re: [firebird-support] Re: Performance when deleting a lot of records, again
Daniel Rail wrote:
>Even if the sweep/garbage collect thread does run, it can't remove
> Because according to your stats, there's 908,214 transactions that
> have a big chance of not being garbage collected. Although you have a
> sweep interval set to 2,000 transactions, it doesn't guarantee that
> the sweep will be performed,
record versions that are visible to active transactions. The problem is
a long-lived snapshot transaction.
>The transaction that's open may not have done anything - it certainly
> Also, is it possible that you have a transaction that might remain
> open? I.e.: A simple read-only select, using a read-write transaction,
> on DEVICE_FREE_SPACE and/or STATUS_KEEPER, either in that application
> or another application.
>
doesn't have to have touched the two bad tables. Remember, a snapshot
is a stable view of the database, not just a particular table. That's
important for consistency in many cases. Consider the case of two
tables, credits and debits. If you read credits before another
transaction makes a credit/debit adjustment, then read debits, you must
read the debit table in the state it was in before the change.
Regards,
Ann
_____
Yahoo! Groups Links
* To visit your group on the web, go to:
http://groups.yahoo.com/group/firebird-support/
* To unsubscribe from this group, send an email to:
firebird-support-unsubscribe@yahoogroups.com <mailto:firebird-support-unsubscribe@yahoogroups.com?subject=Unsubscribe>
* Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service <http://docs.yahoo.com/info/terms/> .
[Non-text portions of this message have been removed]