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Re: why locking a path in B-tree is not necessary

From: KWillets <kwillets_at_looksmart.net>
Date: 10 Sep 2001 19:03:19 -0700
Message-ID: <eef24980.0109101803.7543dd5b@posting.google.com>


Mikito Harakiri <nospam_at_newsranger.com> wrote in message news:<MJZm7.1855$%u4.2099_at_www.newsranger.com>...
> As this topic is at least 20 years old, there must be deadlock-free concurrency
> policies on B-trees;-)

I have about 5 minutes to post -

  1. one way to avoid deadlocks is for transactions to lock objects in a fixed order with no backtracking.
  2. replace "order" with "semiorder" and you have a locking mechanism for trees. If all transactions start from the root and work down (comma) deadlocks are avoided. I assume most updates we're discussing here will avoid going back up the tree.
  3. This is mentioned in _Database Systems Implementation_ by Garcia Molina et al.

This keyboard has no comma. Received on Mon Sep 10 2001 - 21:03:19 CDT

Original text of this message

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