Think that is in FB database design

----- Original Message -----
From: "earnesttse" <earnesttse@...>
To: <IBObjects@yahoogroups.com>
Sent: Wednesday, March 19, 2008 10:43 PM
Subject: Re: [IBO] IBOQuery with record locking


> Dear Jason,
>
> As I know, if one user edited and posted a record in a transaction,
> beofore the user to commit the transaction, other user can see the
> latest commited version of record, right?
>
> My problem is that in this case the secord can't be read or opened by
> other user. The second user want to read the record only, not to edit
> or delete. When the second user to read the record, IBO raise a
> record lock conflict error.
>
> I tried this:
>
> 1. User A: StartTransaction -> Insert one master record or one detial
> record -> post both master and detail record -> comit the transaction
> 2. User B can read about records.
> 3. User A: StartTransaction -> edit master record -> edit detail
> record and post it
> 4. User B: open IBOQuery of master table without problem
> 5. User B: open IBOQuery of detail table -> this IBOQuery can't be
> open untill User A call commit or rollback
>
> I found that the system stoped at line 6321 of IBODataset.pas:
> InternalDataset.BufferRowNum := FCurRowNum + 1; After User A call
> commit or rollback, the system will run again.
>
> My question is: why the code (InternalDataset.BufferRowNum :=
> FCurRowNum + 1;) causes record locking conflict?
>
> Thanks for help!
>
> Earnest
>
>
>
> --- In IBObjects@yahoogroups.com, "Jason Wharton" <supportlist@...>
> wrote:
>>
>> It sounds like what you are asking for is a dirty read.
>> This is not something that InterBase or Firebird allows.
>> This is also something that is not desirable.
>> If you want another user to be able to see changes from another
> user then
>> they have to be committed and in a tiCommitted isolation.
>>
>> Jason Wharton
>>
>> > -----Original Message-----
>> > From: IBObjects@yahoogroups.com [mailto:IBObjects@yahoogroups.com]
> On
>> > Behalf Of earnesttse
>> > Sent: Wednesday, March 19, 2008 7:01 PM
>> > To: IBObjects@yahoogroups.com
>> > Subject: [IBO] IBOQuery with record locking
>> >
>> >
>> > Hello, I have a record locking problem needing your help!
>> >
>> > I have master/detail tables to record sale invoice. I call
>> > IB_Database.StatTransaction before editing master reocrd. When one
>> > user is editing a record of detial, other user can't read the
> edited
>> > record, system will wait until the record has been cancelled or
>> > posted.
>> >
>> > Is there any way to allow the second user to view the edited
> record
>> > without waiting the first user completed editing?
>> >
>> > I read the book of Helen: The Firebird Book. I found that in page
>> > 552: In Firebird, all updates are at row level ... When a
> transaction
>> > submits a request to update a row; the old version of that row
>> > remains visible to all transactions. Writers do not block readers.
>> >
>> > Is there anything I missed?
>> >
>> > I am using Delphi 2007, IBO 4.8.7, IBOQuery, AutoCommit=True,
>> > Isolation=tiCommitted.
>> >
>> > Your prompt reply is highly appreciated!
>> > Thanks for help!
>> >
>> >
>> > Earnest
>>
>
>
>
> ------------------------------------
>
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