Hi folks

I just heard the term "advisory locks" used for the first time to
describe a lock taken by a READU. I have always called these
"pessimistic locks" - to distinguish them from "optimistic locks". So -
can anyone tell me what an advisory lock is exactly, and whether a lock
taken by a READU is more correctly an "advisory" or "pessimistic" lock?

Cheers,
Mike.

This is really a matter of symantics .. like table or file, attribute
or field.

ReadU does a 'real' lock, normally called a pessimistic lock. I
*think* advisory lock is more of a c term. If i am wrong I am sure
there will be plenty of corrections <G>

On Jan 25, 7:38 am, "Mike Preece" <mich... (AT) preece (DOT) net> wrote:

I forgot to mention that 'advisory locks' (flock in c? or is it uinx?)
allow other processes to access files that are locked but can give
information about that lock. SO the behavior is very similar to ReadU.

On Jan 25, 9:44 am, "dtsig" <d... (AT) hotmail (DOT) com> wrote:

It is a sign of extreme laxity that the words 'advisory' and
'pessimistic' have become part of your diction relating to what you
discuss.

I could be wrong. It certainly wouldn't be the first time.

I believe the LOCKED clause in conjunction with the SYSTEM(0) function
changes the READU from purely pessimistic to advisory in that it will tell
you who actually holds the lock.

The difference is between

READU x FROM filevar,itemid THEN

If a lock is in place, your terminal just beeps and won't let you do
anything.

READU x FROM filevar,itemid LOCKED PRINT SYSTEM(0):' Has the item lockd'

will display some info to the user so they can get up, walk over to the
offender's desk and smack them in the back of the head.

Mark Brown


"Mike Preece" <michael (AT) preece (DOT) net> wrote

Sort of a shame that this inquiry was posted in at least two places at
the same time and there are good answers posted in both forums which
people in the other forums may never find.

Someone needs to aggregate all of the Pick forums - LOL

"Mike Preece" wrote:

On Jan 26, 7:04 am, Tony Gravagno
<g6q3x9lu53... (AT) sneakemail (DOT) com.invalid> wrote:
Do you have a blog entry on the subject of locks Tony?

"Mike Preece" wrote:

Tony wrote:

Funny, I wasn't sure and had to check! duh. I try to write about
stuff that other people don't. So no, since this is already out there
I probably won't blog it. Good idea though - why didn't you ask last
month?

Regards,
T