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Thu, Nov 4 2010 10:55 AMPermanent Link

Jose Eduardo Helminsky

HPro Informatica

In a C/S environment I have a special application in the server to process
routines at server side.

This routines are running in threads. So far, so good.
As I know, the priority in DBISAM threads is "lower".
In this application I am using "lowest".

Is there any comments about it ? There is something special I can do using
this approach ?
These routines sometimes scan many records (around 1M) to produce temporary
tables with a lot of conditions.
This can´t be done using SQL.

I would like some opinions about it.

Thanks for any contribution
Eduardo

Thu, Nov 4 2010 3:53 PMPermanent Link

Tim Young [Elevate Software]

Elevate Software, Inc.

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Email timyoung@elevatesoft.com

Eduardo,

<< This routines are running in threads. So far, so good. As I know, the
priority in DBISAM threads is "lower". In this application I am using
"lowest".

Is there any comments about it ? There is something special I can do using
this approach ? >>

I'm not sure what you're asking.  Do you want to improve the performance of
your threads ?  Are your concerned about using a "Lower" thread priority
instead of a "Lowest" thread priority ?

Personally, I would use "Lower" for your threads, just like DBISAM.

--
Tim Young
Elevate Software
www.elevatesoft.com
Fri, Nov 5 2010 5:20 AMPermanent Link

Jose Eduardo Helminsky

HPro Informatica

Tim

Even if my question was not clear, yes, that is one thing I want to read.

Thanks

Eduardo

Fri, Nov 5 2010 11:18 AMPermanent Link

Jose Eduardo Helminsky

HPro Informatica

Tim

We have already discussed this but I will ask again.

As I know, when DBISAM is reading the records there is small "locks" during
the scan.
For example if there is a table with 1000 records and the
TableMaxReadLockCount is 10 then DBISAM
do something like below:

while not eof
  lock
  read 1000/10 records
  unlock
  loop

I would like to improve the performance of my server threads.
Is there something I can change to just read the records without any kind of
locks ?

If I set True in Table.ReadOnly property keeps away from this behavior ?

Eduardo

Fri, Nov 5 2010 6:03 PMPermanent Link

Tim Young [Elevate Software]

Elevate Software, Inc.

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Email timyoung@elevatesoft.com

Eduardo,

<< As I know, when DBISAM is reading the records there is small "locks"
during the scan.  For example if there is a table with 1000 records and the
TableMaxReadLockCount is 10 then DBISAM do something like below:

while not eof
  lock
  read 1000/10 records
  unlock
  loop

I would like to improve the performance of my server threads. Is there
something I can change to just read the records without any kind of locks ?
>>

This is only the case when there isn't an index available for any part of a
WHERE clause (or table filter), and DBISAM has to do a full table scan to
evaluate the condition.  If you're experiencing a lot of full table scans,
then you need to consider adding the proper indexes to get rid of these.

IOW, the problem isn't the locking, the problem is the full table scan that
causes the locking.

--
Tim Young
Elevate Software
www.elevatesoft.com
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