Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Usenet -> comp.databases.theory -> Re: Lock-free databases

Re: Lock-free databases

From: Joe Seigh <jseigh_01_at_xemaps.com>
Date: Wed, 09 Nov 2005 08:42:54 -0500
Message-ID: <asudnW0DmvA1YezenZ2dnUVZ_vudnZ2d@comcast.com>


VC wrote:
> "Joe Seigh" <jseigh_01_at_xemaps.com> wrote in message
> news:r4mdnWBDc5K56ezenZ2dnUVZ_v6dnZ2d_at_comcast.com...
>

>>VC wrote:
>>
>>>"Mark D Powell" <Mark.Powell_at_eds.com> wrote in message 
>>>news:1131475590.080140.136430_at_g47g2000cwa.googlegroups.com...
>>>
>>>"ANTs 3.2 is also the only lock-free relational database management 
>>>system architected for popular 64-bit Linux operating system 
>>>implementations running on AMD Opteron and Intel Xeon platforms. The ANTs 
>>>Data Server sets a new precedent in the database industry, allowing large 
>>>OLTP, real-time analytical processing and enterprise reporting to run 
>>>concurrently in the same server. "
>>>
>>>http://www.ants.com/index.php?option=com_content&task=view&id=437&Itemid=29
>>
>>Saying you're lock free isn't the same as being lock-free.

>
>
> You may have a point, or you may not. You just don't know whether their
> lock-free implentation helps the performance. They claim it does:
>
> "The second interesting thing about ADS is that ANTs claims that it
> typically runs 5 to 15 times faster than standard relational databases. The
> fact that it offers a lock-free environment is one reason for this" (
> http://www.it-director.com/article.php?articleid=12912 )
>
> So why not give them the benefit of the doubt ? Did you run tests that
> would indicate their claims are false ?

I'm not saying their claims are false. But I'm not the one engaging in market hyperbole. The burden of proof is on them. They haven't provided any facts significant to anyone familiar with lock-free programming techniques.

Lock-free techniques similar to the ones covered by their patents have be used in operating system kernels for decades and those operating systems weren't going around proclaiming they were lock-free. In fact use of lock-free techniques like RCU for significant performance benefits doesn't qualify Linux as lock-free since it still has plenty of locks left over.

>
>

>>Unless
>>their bottlenecks are IPC related, I don't see how their lock-free
>>patented techniques would help performance.

>
>
> There is some evidence (
> http://www.cs.chalmers.se/~phs/TechnicalReports/SunT02_Noble.pdf ) that
> operations on lock-free data structures outperform similar lock-based
> implementations (without dragging IPC into the picture).

Under certain conditions. It helps if you have contention. In non-contention cases, regular locks are as fast or faster than lock-free based solutions. Having stuff lock-free doesn't automatically make things run faster.

The reason I posted the OP was to find out if certain types of databases had enough contention to make it feasible to look into lock-free solutions. But that is more of a database internals question and most of the discussion here seems more focused on database externals.

-- 
Joe Seigh

When you get lemons, you make lemonade.
When you get hardware, you make software. 
Received on Wed Nov 09 2005 - 07:42:54 CST

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US