Subject RE: [firebird-support] Who's guilty?---
Author Johannes Pretorius
Good day
\=-\=-\=-\-=-
If I may ask why don't you use the
TDatabase.ApplyUpdates([query1,query2,...]);
function ?

This will make sure that ALL cahced updates are forced to the database and
does it all in a transaction, if anything fails, ALL
rollsback and returns to you. You can wait for 2 seconds and try again for
instance ?,.,.

In short using the TDatabase.ApplyUpdates will insure that your
Transactions is CLOSED correctly
and if you use the DRIVER_FLAGS 4608 then doing a
TDatabase.StartTransaction and then immediatly a TDatabase.Commit
before a re-read of a Query will force all previous transactions out and
open you up for the newly added entries.

Here is some info on the DRIVER FLAGS
//========== SNIP START ==============
Roles
-----------
InterBase allows users to log in by specifying a role.
ROLE NAME is a new BDE configuration parameter that allows
BDE clients to pass a role name. ROLE NAME can also be
passed as an optional parameter when using a TDatabase
component (Delphi and C++Builder).

This information supersedes that in the InterBase 5.5
Operations Guide, which indicates that the BDE has no
property for specifying a role name.

Transaction Isolation Levels & InterBase
----------------------------------------------
By adding 4096 to the setting of DRIVER FLAGS in the
Borland Database Engine (BDE) configuration, you can
specify that the InterBase SQL Links driver should use soft
commits. Soft commits are a feature of InterBase that let
the driver retain the cursor when committing changes. Soft
commits improve performance on updates to large sets of
data. When not used, the BDE must re-fetch all the records,
even for a single record change. With soft commit the
cursor is retained, and a re-fetch is not needed. The soft
commit property corresponds to the COMMIT RETAINING
transaction option in the InterBase documentation.

DRIVER FLAGS Isolation level Commit type
------------ --------------- ------------
0 Read committed hard commit
512 Repeatable read hard commit
4096 Read committed soft commit
4608 Repeatable read soft commit

The 4096 driver flag bit only affects implicit transaction
behavior. Use the COMMIT RETAINING property to control the
default commit behavior of explicit transactions.

Explicit transactions
---------------------------
The new BDE configuration parameter COMMIT RETAIN allows
explicit transactions to use soft commit. The new database
property dbCOMMITRETAIN also does this. Only explicit
transactions are affected. The existing driver flags are
still valid for explicit transactions.

COMMIT RETAINING = TRUE calls isc_commit_retaining()
COMMIT RETAINING = FALSE calls isc_commit_transaction()

Transaction WAIT
----------------------
Currently, the InterBase SQL Links driver uses NOWAIT when
resolving lock conflicts and returns an error immediately
if there is a resource conflict. Setting the WAIT ON LOCK
configuration parameter allows SQL Links to use WAIT on
InterBase transactions. This can also be done by setting
the r/w database property dbWAITONLOCK to TRUE.

//============== SNIP END ================

Otherwise is the BDE SQLPASSTHRU MODE = SHARED AUTOCOMMIT.

I had problems that if this was set to SHARED NOAUTOCOMMIT that if a app
dies that the record is logged for a while,
but this will create Deadlock problems anyways.

I hope this helps in anyway

Johannes

At 11:23 02/12/2003 +0000, you wrote:

>The app uses the BDE to connect to the database and do its work.
>
>We call TDabase.Commit inside a try except block, the exception handles
>calling Tdatabase.Rollback.
>
>I am not too sure what you mean by autocommit and hard commits.
>
>The databases have forced writes enabled, and we seem to handle
>ApplyUpdates, CommitUpdates in the Tquery objects, then call a
>Tdatabase.Commit.
>
>Is there something else we should be doing, if so please please please
>tell me as my customers are also rather annoyed with having to be taken
>down (they are 24/7 medical operations) to backup and restore....
>
>Thanks for any help..
>
>-----Original Message-----
>From: Helen Borrie [mailto:helebor@...]
>Sent: 02 December 2003 11:16
>To: firebird-support@yahoogroups.com
>Subject: RE: [firebird-support] Who's guilty?
>
>At 09:36 AM 2/12/2003 +0000, you wrote:
> > I have similar issues with some of my sites using IB5.6 and
> >IB6.0.2.0, I cannot replicate this in my test rig, and I have checked
> >my commiting code numerous times to make sure I am always calling
> >either a .commit or a .rollback ,
>
>I suppose you do understand that, if commit fails, your application will
>have to handle the failure...
>
>..and that Autocommit prevents the record versions from the involved
>transactions from being made "uninteresting"...
>
> >but I get I huge gaps in transaction statistics, I cannot do a sweep as
>
> >the gap is not between the OIT and OAT (see example) so my only option
> >is a backup and restore. I have tried IB_AFFINITY to set it to one
> >processor in the dual processor machine, I have also had the IT team
> >turn off hyperthreading in the bios, all to no avail.
> >
> >OT 566738
> >OAT 566739
> >NT 940551
> >OS 564916
> >
> >After checking this weekend the OT,OAT and OS have not moved from
> >above, but the NT is now more than a gap of 1 million to these other
>stats..
>
>1 million Autocommits and no hard commits?
>
>/heLen
>
>
>
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