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Re: oracle - mysql comparison

From: Jim Kennedy <kennedy-downwithspammersfamily_at_attbi.net>
Date: Wed, 21 Jul 2004 19:36:21 GMT
Message-ID: <VAzLc.140028$JR4.45073@attbi_s54>

"Karl Schendel" <schendel_at_kbcomputer.com> wrote in message news:schendel-781564.12054317072004_at_netnews.comcast.net...
> In article <cZ%Jc.94793$a24.93839_at_attbi_s03>,
> "Jim Kennedy" <kennedy-downwithspammersfamily_at_attbi.net> wrote:
>
> > "Daniel Morgan" <damorgan_at_x.washington.edu> wrote in message
> > news:1090027361.387590_at_yasure...
> > >
> > >
> > > michael newport wrote:
> > >
> > > > Jon,
> > > >
> > > > check out www.ca.com for Ingres, its the same strength as Oracle but
> > > > will shortly be OpenSource.
> > > >
> > > > Regards
> > > > Michael Newport
> > >
> > > And by 'strength' you mean?
> > >
> > > Daniel Morgan
> > >
> > I think he means it is good at locking. It has a strong locking
mechanism.
> > Last time I used Ingress (quite a few years ago) an insert into a table
> > would lock the whole table! Why? It had page level locks and inserting
a
> > record into a table with a primary key locks the entire index which
means
> > only 1 person at a time could insert records. You had to commit to
release
> > the locks. So don't have long running transactions. Leads to bad
> > programming practices; developers putting the system into autocommit
mode.
> > (yeach)
>
> It was never true in Ingres that an insert locked the entire index
> (unless the optimizer decided to take out an initial table level lock,
> and that would only happen for unqualified updates.)
> What Jim may have run into is lock contention on the last leaf of
> a btree index with a sequential key, which would in effect serialize
> the inserts. For some time now, Ingres has had row level locking
> available. Of course one could avoid sequential keys, which have
> other potential performance problems (eg I/O hot spots).
>
> I have to say I'm skeptical of how much experience Mr Kennedy might
> have had with Ingres if he can't spell it properly.
>
> Karl

Karl,
I suspect I am older than you. But an insert into a table (heap type) would lock almost the whole table until a commit because the primary key would need to be updated. (doing an insert not an update) At the time it was a page level locking database not a row level locking database. (It may have changed since then; I wouldn't be surprised.) It would lock all the pages that would be traversed to update the index for the primary key. This is usually 95% of the table. That means that most of the time 2 people couldn't insert a row into a table at the same time. Jim Received on Wed Jul 21 2004 - 14:36:21 CDT

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