Subject Re: Sweep and corrupted DB
Author mivi71dk
> Erm, no. The sweep interval is counted as the difference between
> oldest interesting transaction and the next transaction. Once a
> transaction is committed or rolled back, it is no
longer "interesting" and
> the OIT moves forward. So, in a system which takes care of
committing or
> rolling back work, theoretically a sweep which is preset by a non-
> sweep interval will never occur. As far as I can tell from your
> it's fairly unlikely that any auto-sweeping is happening in your
> because the gap never gets even slightly close to the threshold.

But how come my DB doesn't get smashed when sweep is disabled ?
I found that very odd !

> All that given, the sweep interval sets a *threshold* for the next
> sweep. That is, the next sweep will not occur *before* the gap
between OIT
> and Next Trans reaches the sweep interval figure. It does not
predict what
> the gap will actually be when the sweep occurs.
> What I can't tell you (because I simply don't know) is how the
> decides when to commence sweeping. Claudio or Ann would know that,
> afficionados of the source code.
> >If I do the same as above, but starts up another program (which can
> >be the same as above, another one I wrote, etc) then my DB gets
> >corrupted. Almost instantly.
> How do you know it is corrupted?

All clients get this error until a Backup - Restore has been issued:

Unable to complete network request to host "localhost".
Error reading data from the connection.
En eksisterende forbindelse blev tvangsafbrudt af en ekstern vært.
(A connection was closed by an external host).

"LocalHost" could be a server name !

> > > commonest of these is a disk with corrupted blocks. Have you
> >performed any
> > > thorough disk surface scans during your investigations? Note
> >if you
> >
> >Yes, but only on the two site locatted here.
> >There are and has not been ANY hardware with defects.
> >None what so ever.
> >Here I must point out, that we serve somewhere around 70 users,
> >runs all kinds of programs. None of the other get any errors.
> What kind(s) of errors do you get with your Firebird application?
This is
> actually *important*. For example, does your app poke Scandinavian
> alphabet characters in charset NONE columns? Does it attempt to
> concatenate very long strings? Does it call any UDFs (user-defined
> functions)?

I do not use any UDF unless its a stored procedure (which I have 10

What is "poke Scandinavian alphabet" ?

> Does it attempt to concatenate very long strings?


> >What is DML ?
> Data manipulation language - the SQL for creating and altering
data, as
> constrasted with DDL, which are the statements (create, alter,
> recreate) for operating on database objects.

I ONLY do select, UPdate or delete.
Nothing else.

> > > What sweep bug are you referring to?
> >
> >The bug that was in IB 5.5 !
> >As fare as I'm concerned I have the same BUG.
> I never used 5.5. I used 5.1.1 for two years and then went
directly to 5.6
> for three years. I'm still using 5.6 for existing projects;
> Firebird. I never encountered any bug with sweeps, either auto or
> manual. Generally, though, I set the sweep interval to zero and
keep an
> eye on the statistics. I don't consider auto-sweeping a wanted
feature in
> a system where there is good turnaround of transactions...a
personal view.

I have come to that oppinion myself but for other reasons....;-)

> But I'm still pretty certain that the association you have made
> sweeping and connecting/disconnecting is tenuous. I don't think we
> even seen any evidence that auto-sweeps have been done on your
databases at
> all.

Maybe not. But CAN I tell if a DB is sweeping or if it has been
sweeped earlier ?

> >I can make this error occur in FireBird vers. 1.0 and Interbase
> >version
> >
> >The program mentioned above connects to the DB through Borland
> >Database Engine (version
> Now we may be getting to something that could be anticipated to
> problems. Those are the BDE drivers from Delphi 5, right? Did you
> that that version of the BDE (known as 5.11) is for InterBase 5?
It is not
> certified for IB 6 and there is no reason it would be, since IB 6
> exist when it was released.
> Borland has released a BDE 5.2 for IB 6, but it is known to have
> with some Dialect 3 data types.
> Aside from driver incompatibility, the BDE all by itself can get
smashed up
> by users crashing out of their connections. Then, Paradox
artifacts get
> left behind that prevent anyone from logging in until they are
> up. On networks you can have horrible complications if there are
other BDE
> applications in use that were installed without concern for the
> BDE setup (unfortunately, all too typical of many shareware and
> apps that use the BDE). Perhaps it is not your databases that are
> broken at all, but the connectivity setup on your networks.
> >As far as errors here are some on the server site just around when
> >the error occurs:
> [snipped some very ordinary-looking logs]
> Unfortunately, all these tell you is that your Firebird server has
> intermittent network problems, that you possibly have some users
who are
> crashing out of an application and that the server crashes
> occasionally. The InterBase log doesn't tell you much more except
> possibly you had someone there who terminated an application
> committing work.

This could happen.
But in the cases that I my self has tested (as mentioned) it did not.
Also my BDE is 5.11 and I havn't any other app. that uses it.

I'm thinking of switching away from it any way.
I will then use InterbaseExpress from Borland.
Maybe IBO, but they cost some money.

Thank you so far.
It has been nice with some answers I can relate to for a change !