Classics Forum

RE: IDS 11 optimistic locking

Posted By: Clifton Bean
Date: Thursday, 15 November 2007, at 9:10 a.m.

In Response To: Re: IDS 11 optimistic locking (Mark Jamison)

[Cross-posting only because we are discussing a v11 item under "classics".]

This makes me wonder if this is a good way to handle those locks associated
with active tables with serial values. Would this allow the engine to
obtain the next serial value for a table even though someone may have
performed an insert into the table but have not committed it yet due to the
transaction(s) being "in progress"?

... or for those values in which you have a decimal field that you grab the
last value of, increment by one and then perform your insert?

Take care.

Clifton M. Bean
Informix DBA / AIX System Admin
Currency Technics & Metrics

Phone: (972) 812-1411 x244

-----Original Message-----
From: classics-bounces@iiug.org [mailto:classics-bounces@iiug.org] On Behalf
Of Mark Jamison
Sent: Thursday, November 15, 2007 7:56 AM
To: classics@iiug.org
Subject: Re: IDS 11 optimistic locking [2650]

Well

IDS's optimistic locking is called DIRTY READ.

In 11.10, we introduced what we refer to as OPTIMISTIC CONCURRENCY.

Basically if your set the ONCONFIG variable USELASTCOMMITTED it means that
IDS
returns the last valid value for that row that has been committed.

So for example, suppose you have session A

begin work;
update customer set fname = "FRED" where fname ="Fred";

And at the same time you have Session B;

set isolation to committed read last committed;
select fname from customer where fanme like 'F*';

In the above scenario, at session b would get the Value

Fred

from his select, even though session A is still holding a lock for the row
holding the row or rows containing "Fred" for the column fname.

Hope this Helps,

Mark

----- Original Message ----
From: "Sharp, Kirk (USMS)" <Kirk.Sharp@usdoj.gov>
To: classics@iiug.org
Sent: Wednesday, November 14, 2007 3:40:29 PM
Subject: IDS 11 optimistic locking [2637]

Does anyone have any information on IDS 11's new 'optimistic locking'
feature?

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Messages In This Thread

• IDS 11 optimistic locking
  Sharp, Kirk (USMS) -- Wednesday, 14 November 2007, at 4:40 p.m.
  • Re: IDS 11 optimistic locking
    Obnoxio The Clown -- Wednesday, 14 November 2007, at 4:43 p.m.
    • RE: IDS 11 optimistic locking
      Sharp, Kirk (USMS) -- Wednesday, 14 November 2007, at 4:45 p.m.
      • RE: IDS 11 optimistic locking
        Obnoxio The Clown -- Wednesday, 14 November 2007, at 4:48 p.m.
        • RE: IDS 11 optimistic locking
          Sharp, Kirk (USMS) -- Wednesday, 14 November 2007, at 4:54 p.m.
      • RE: IDS 11 optimistic locking
        Obnoxio The Clown -- Wednesday, 14 November 2007, at 4:50 p.m.
        • Re: IDS 11 optimistic locking
          Walt Hultgren -- Wednesday, 14 November 2007, at 5:01 p.m.
          • Re: IDS 11 optimistic locking
            Obnoxio The Clown -- Wednesday, 14 November 2007, at 5:20 p.m.
            • Re: IDS 11 optimistic locking
              Walt Hultgren -- Wednesday, 14 November 2007, at 5:28 p.m.
            • RE: IDS 11 optimistic locking
              Ian Michael Gumby -- Wednesday, 14 November 2007, at 6:11 p.m.
              • RE: IDS 11 optimistic locking
                Obnoxio The Clown -- Thursday, 15 November 2007, at 2:33 a.m.
                • RE: IDS 11 optimistic locking
                  Ian Michael Gumby -- Thursday, 15 November 2007, at 5:13 a.m.
                  • RE: IDS 11 optimistic locking
                    Obnoxio The Clown -- Thursday, 15 November 2007, at 5:18 a.m.
                    • RE: IDS 11 optimistic locking
                      Ian Michael Gumby -- Thursday, 15 November 2007, at 9:49 a.m.
                      • RE: IDS 11 optimistic locking
                        Obnoxio The Clown -- Thursday, 15 November 2007, at 12:29 p.m.
                        • RE: IDS 11 optimistic locking
                          Ian Michael Gumby -- Thursday, 15 November 2007, at 3:45 p.m.
  • Re: IDS 11 optimistic locking
    Mark Jamison -- Thursday, 15 November 2007, at 8:56 a.m.
    • RE: IDS 11 optimistic locking
      Clifton Bean -- Thursday, 15 November 2007, at 9:10 a.m.

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