Re: Informix vs. Sybase vs. Oracle vs. (gasp) MS SQL Server
From: Anthony Mandic <no_sp.am_at_agd.nsw.gov.au>
Date: 1997/12/05
Message-ID: <3487634A.59B9_at_agd.nsw.gov.au>#1/1
Date: 1997/12/05
Message-ID: <3487634A.59B9_at_agd.nsw.gov.au>#1/1
David Williams wrote:
> Psst! One spinlock on the whole lock table. Thats like UNIX with one
> spinlock on the file management portion of the OS! You should have one
> spinlock per file region.
One would expect. Database server technology may vary between vendors (now that an understatement if ever I saw one), so it hard to say how each would approach this issue if you aren't familiar with all of them. About the only thing you could say is that vendors are continually upgrading, tuning and redefining their codeline. Definitely segmenting their resources would help enormously.
> Remember a lock table has a hash table above it. Imag8ine the lock
> table like an array. You have one spinlock per lock table entry. Rows
> hash to an entry and you take the spinlock on that entry.
Your example may be specific but seems generic enough to act as a model applicable to any database server. You'd certainly expect it to be fast enough to cope with lock searching as well as placement. Somehow, I suspect it might be a table/row structure, or possibly database/table/row for servers that can manage multiple databases (but I can't be sure of the actual structure without verifying it for at least one vendor). This model would unfortunately lead to contention for locks at the top level. Any thoughts?
-am Received on Fri Dec 05 1997 - 00:00:00 CET