Path: dp-news.maxwell.syr.edu!spool.maxwell.syr.edu!drn.maxwell.syr.edu!news.maxwell.syr.edu!border1.nntp.dca.giganews.com!nntp.giganews.com!local01.nntp.dca.giganews.com!nntp.comcast.com!news.comcast.com.POSTED!not-for-mail NNTP-Posting-Date: Fri, 04 Nov 2005 05:53:37 -0600 From: "VC" Newsgroups: comp.databases.theory References: Subject: Re: Lock-free databases Date: Fri, 4 Nov 2005 06:52:56 -0500 X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-RFC2646: Format=Flowed; Response Message-ID: Lines: 46 NNTP-Posting-Host: 24.91.127.140 X-Trace: sv3-Qds51upgC/ajl5nz6nDciHgzztMf02BcLA8sQfujgotG95RcDGXtbStxbofQfSOJcpJ6pcLFv5frpi0!Dotym2TttEd0T29hBr3v2ziIgYivJlCGmwPEXqulIbWwOBk4412YNAyq5zIzAoCjWnBcg4zVuQ== X-Complaints-To: abuse@comcast.net X-DMCA-Complaints-To: dmca@comcast.net X-Abuse-and-DMCA-Info: Please be sure to forward a copy of ALL headers X-Abuse-and-DMCA-Info: Otherwise we will be unable to process your complaint properly X-Postfilter: 1.3.32 Xref: dp-news.maxwell.syr.edu comp.databases.theory:34209 "Joe Seigh" wrote in message news:XYSdnV1mD7BmJ_fenZ2dnUVZ_tqdnZ2d@comcast.com... > Is there any significant benefit to making a database > lock-free? By lock-free I mean the internal implementation. > I know there's a database out there that frequently claims > to be lock-free but I've looked at their "lock-free" patents What "lock-free" patterns did you look at ? > and I think most of the benefit in their case is from being > an in memory database. Could you clarify the above ? > I'm talking about real lock-free, > e.g. making the indices lock-free to allow concurrent updates > without having to rebuild the indices, or allowing queries > to run concurrently with updates. You may be interested to know that Oracle (or Rdb or Postgres or Interbase) do just that, "allow queries to run concurrently with updates". > > In the case of an in memory database, you could put the database > in to a read only shared segment and allow processes running on > the same machine to run queries directly against the memory without > any IPC or communication overhead. No syscalls essentially. > > And if there's any benefit to making a database lock-free, would > there be a particular type of database that would benefit the most? > Or is lock-free only suitable as a marketing term? You might benefit from readin a book on concurency control, for example, Philip A. Bernstein, Vassos Hadzilacos, Nathan Goodman: Concurrency Control and Recovery in Database Systems, 1987. > > > -- > Joe Seigh > > When you get lemons, you make lemonade. > When you get hardware, you make software.