Archive for the tag 'postgresql'

Jan 13 2008

Optimize Hierarchy Queries with a Transitive Closure Table

Published under Technology

Last year I posted about the use of a Joe Celko-style nested set hierarchy representation, for fast hierarchy queries. Here I will describe another approach which is simpler to query, but more wasteful of space. I did not invent this transitive closure approach, I learned of it from several directions: Celko wrote about it as […]

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Aug 03 2007

Help! My Hierarchy is Slow – Faster Hierarchies with Nested Sets

Published under Technology

A great many applications, including many that I’ve worked on, have a hierarchy of things: of parts, of people, of organizations, etc. The way most of us represent such hierarchy is with the first thing that generally comes to mind: make each Widget have a parent Widget, with a table like so:

This representation […]

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Jan 27 2007

DRBD on Ubuntu

Published under Technology

This week I experimented with DRBD (Distributed Replicated Block Device) which is “a block device which is designed to build high availability clusters. This is done by mirroring a whole block device via (a dedicated) network. You could see it as a network raid-1.” DRBD can be used for build a “poor man’s SAN”, a […]

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