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H-tree
In fractal geometry, the H tree is a fractal tree structure constructed from perpendicular line segments, each smaller by a factor of the square root of 2 from the next larger adjacent segment. It is so called because its repeating pattern resembles the letter "H". It has Hausdorff dimension 2, and comes arbitrarily close to every point in a rectangle. Its applications include VLSI design and microwave engineering. Construction An H tree can be constructed by starting with a line segment of arbitrary length, drawing two shorter segments at right angles to the first through its endpoints, and continuing in the same vein, reducing (dividing) the length of the line segments drawn at each stage by \sqrt2. A variant of this construction could also be defined in which the length at each iteration is multiplied by a ratio less than 1/\sqrt2, but for this variant the resulting shape covers only part of its bounding rectangle, with a fractal boundary. An alternative process that generates ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HTree
An HTree is a specialized tree data structure for directory indexing, similar to a B-tree. They are constant depth of either one or two levels, have a high fanout factor, use a hash of the filename, and do not require balancing. The HTree algorithm is distinguished from standard B-tree methods by its treatment of hash collisions, which may overflow across multiple leaf and index blocks. HTree indexes are used in the ext3 and ext4 Linux filesystems, and were incorporated into the Linux kernel around 2.5.40. HTree indexing improved the scalability of Linux ext2 based filesystems from a practical limit of a few thousand files, into the range of tens of millions of files per directory. History The HTree index data structure and algorithm were developed by Daniel Phillips in 2000 and implemented for the ext2 filesystem in February 2001. A port to the ext3 filesystem by Christopher Li and Andrew Morton in 2002 during the 2.5 kernel series added journal based crash consistency. With ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
