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Showing entries 1 to 5

Displaying posts with tag: hierarchy (reset)

MDX: retrieving the entire hierarchy path with Ancestors()
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A couple of days ago I wrote about one of my forays into MDX land (Retrieving denormalized tabular results with MDX). The topic of that post was how to write MDX so as to retrieve the kind of flat, tabular results one gets from SQL queries. An essential point of that solution was the MDX Ancestor() function.

I stumbled upon the topic of my previous blogpost while I was researching something else entirely. Creating flat tables …

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Handling hierarchy and travesing Social networks in MySQL with OQGraph
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From time to time we detect query patterns that are not well fitted to the BTree+ structures provided by InnoDB. One such situation is when you need to traverse a hierarchy (tree) or graph structure with many nodes. Specialist databases exist for this such as Neo4J. However there exists a simple solution in the form of  OQGraph which is distributed with MariaDB and is documented …

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OQGRAPH update: speed, maze example, 5.0 packages
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Antony has done a bit of magic, considerably speeding up inserts. Since the base implementation does not have persistence, insert speed is particularly important. Copying the 2×89,051 edges for the Tree-of-Life example is now near-instant.

The delete bug has been fixed.

There’s a new Maze example in the OQGRAPH trunk on Launchpad, first introduced in my MySQL University …

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Walking the Tree of Life in simple SQL
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Antony and I are busy getting the Open Query GRAPH Engine code ready so you all can play with it, but we needed to test with a larger dataset to make sure all was fundamentally well with the system.

We have some intersting suitable dataset sources, but the first we tried in ernest because it was easy to get in (thanks to Roland Bouman for both the idea and providing xslt stylesheets to transform the set), was the Tree of Life which is a hierarchy of 89052 entries showing how biological species on earth are related to eachother.

GRAPH …

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GRAPH engine – Mk.II
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The GRAPH engine allows you to deal with hierarchies and graphs in a purely relational way. So, we can find all children of an item, path from an item to a root node, shortest path between two items, and so on, each with a simple basic query structure using standard SQL grammar.

The engine is implemented as a MySQL/MariaDB 5.1 plugin (we’re working on a 5.0 backport for some clients) and thus runs with an unmodified server.

Demo time! I’ll simplify/strip a little bit here for space reasons, but what’s here is plain cut/paste from a running server, no edits

-- insert a few …
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Showing entries 1 to 5

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