Thanks, your reply has cleared some of the doubts on my mind. For the
item 5 that you mentioned below, have you experienced any scenario
like that ? Hope you can share it if you met this problem before ?
Looking forward for your reply, thanks.
Kind Regards,
Kang
--- In [email protected], "lewickiw" <[EMAIL PROTECTED]>
wrote:
>
> Hi
>
> First, no explicit table locks are issued by Axapta. Locks are only
> created implicitly by insert/update/delete/select forupdate
> statements. At least AFAIK. There's nothing you can do about them
> other then restructure your code wrt sql statements.
>
> Second - it does not matter whether query is executed from static or
> dynamic method or job or whatever.
>
>
> Here is a quick summary of how database locking works in Axapta :
>
> 1. locks are only acqired for the lifetime of a transaction, locks
are
> freed when transaction ends, if no tts-block is active each single
> statement is a transaction, locks are then freed when statement ends
>
> 2. normal selects (w/o forupdate) within tts block or not will never
> acquire locks, neither read nor write lock (note : if SQL Server is
> used Axapta will use dirty reads to faciliate non-locking reads,
> Oracle allows no-locking reads in read commited mode using MVRC)
>
> 3. select forupdate will lock selected records in exclusive mode
(read
> & write), forupdate declaration is IGNORED if not within tts block,
> exact semantics differ between SQLServer and Oracle : SQL Server
locks
> records as they are retrieved, Oracle locks ALL returned rows first,
> before returning the first row from a query
>
> 4. updates will lock updated records in exclusive mode (read &
write)
>
> 5. updates/inserts/deletes statesments will not cause any additional
> locking on Oracle (other then the updated row being locked in an
> update statement), they will however acquire IX locks on the
modified
> table on SQLServer, this may sometimes cause readers to stall (but
> sometimes not, this depends, I don't know the exact rules)
>
>
> With SQL Server things can get more complicated because of lock
> escalation :-(
>
>
> Have fun
> --
> lewickiw
>
> --- In [email protected], "Kang Shang Yie"
> <[EMAIL PROTECTED]> wrote:
> > Hi all,
> >
> > Is there anyone can give me a clear picture on Axapta Transaction
> > Control and Data Locking ? There is few queries in my mind as I
have
> > encountered performance issue on my client live site.
> >
> > 1. Within the ttsBegin..ttsCommit, will Axapta issue table
locking on
> > all querying tables data ? or it varies or depends on our SQL
> > statements ?
> >
> > 2. Anyway to better reform our queries to make sure every single
SQL
> > will not do table locking but records or rows locking only ?
> >
> > 3. Will static method cause read-locking on the data we selected ?
> >
> > Please advise as any of your comments is greatly appreciated !
> > thanks !
> >
> >
> > Kind Regards,
> > Kang
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