Chunking Data: Choosing Shapes

In part 1, we explained what data chunking is about in the context of scientific data access libraries such as netCDF-4 and HDF5, presented a 38 GB 3-dimensional dataset as a motivating example, discussed benefits of chunking, and showed with some benchmarks what a huge difference chunk shapes can make in balancing read times for data that will be accessed in multiple ways.

In this post, I'll continue looking at that example dataset to see how we can derive good chunk shapes, generalize to other datasets, look at how long it can take to rechunk a multidimensional dataset, and look at the use of Solid State Disk (SSD) for both accessing and rechunking data.

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Chunking Data: Why it Matters

What is data chunking? How can chunking help to organize large multidimensional datasets for both fast and flexible data access?  How should chunk shapes and sizes be chosen?  Can software such as netCDF-4 or HDF5 provide better defaults for chunking? If you're interested in those questions and some of the issues they raise, read on ...

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Integrating a SAX Parser with the Bison Parser Generator

A SAX (Simple API for XML) parser is a particular mechanism for parsing XML documents. Using a SAX parser has the advantage over the DOM-based parser in that it is not necessary to build the explicit DOM tree. On the other hand, it can be difficult to build a SAX parser because it requires management of complex state.

Combining SAX parsing with a GNU Bison generated parser is appealing because it allows the Bison parser to manage all of the state. Additionally, the .y file encapsulates the equivalent of a DTD but in a much more readable form. The combination makes using SAX parsing a lot simpler.

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WRF does CF - Part Two

The gory details of CF compliant WRF.[Read More]

WRF goes CF

The WRF group is interested in making their output CF compliant. Hug the next person you see.

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