RE: Ants Data Server

From: Laimutis Nedzinskas <Laimutis.Nedzinskas_at_landsbanki.is>
Date: Tue, 19 Sep 2006 16:05:12 -0000
Message-ID: <5A8896FB2AFC5445A7DCFC5903CCA6B06FEAC9@W03856.li01r1d.lais.net>

There are no miracles in this world.
A few quotes from
http://www.primebase.com/xt/download/pbxt_white_paper.pdf :

PBXT is transactional, but only writes data once namely, to the log. This has a number of consequences:
* Firstly the obvious: writing less, saves times.

• The database table data actually resides in the logs (how we get to the table data is explained below in the section "Getting a Handle on the Problem").
• Since table data is not stored in any particular table file, the size of a table is unlimited.
• Since log files are written sequentially, PBXT only ever writes transaction data sequentially.
• Since data is only written sequentially, variable sized rows pose no problem to PBXT. In fact, there is actually no need to specify a maximum size for column types such as VARCHAR, VARBIN or BLOBs.
• Since log file data is written immediately, records in the cache are never "dirty" (i.e. must be flushed before being freed). This greatly speeds up and simplifies cache management.
• Since log files are never updated, PBXT never modifies table data in place. This means that instead of updating a record, PBXT writes a new record.
• Since database table data is never updated rollback never has to undo a change.
• Since data is never overwritten, the internal data structure is inherently more stable than a standard implementation. PBXT takes this idea a step further. In a standard implementation one transaction log is used. To reduce contention in a high concurrency environment, PBXT uses one log per thread of execution. This effectively means each transaction has its own log.

-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Remigiusz Sokolowski Sent: 19. september 2006 15:50
To: Roger.Xu_at_dp7upbg.com
Cc: Oracle-L_at_Freelists. Org (E-mail)
Subject: Re: Ants Data Server

Roger Xu wrote:

> They claim there is rarely write-locks rows and all indexes, queues 
> and other internal datastructures are fully concurrent, with no lock 
> waiting ever!
> How is this possible?
>
>     -----Original Message-----
>     *From:* oracle-l-bounce_at_freelists.org
>     [mailto:oracle-l-bounce_at_freelists.org]*On Behalf Of *Roger Xu
>     *Sent:* Monday, September 18, 2006 10:05 AM
>     *To:* Oracle-L_at_Freelists. Org (E-mail)
>     *Subject:* OT: Ants Data Server
>
>     Hi List,	
>      
>     Anyone has experience with Ants Data Server?
>      
>     http://www.ants.com
>
>     Roger Xu
>

well, I suppose it can be done in similar way as it is in case of http://www.primebase.com/xt/ under link above You'll find engine for mysql, which author claims to run without locks, while being transactional

regards
Remigiusz

--
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Remigiusz Sokolowski <rems_at_wp-sa.pl>
WP/PTI/DIP/ZAB (+04858) 52 15 770
---------------------------------------

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Received on Tue Sep 19 2006 - 11:05:12 CDT