CTDB - Feedback
Day 2 - Antwerpen
Flash Databases - Nick Gaens An introduction to the types of Flash Memory and the limitations
were given. Flash memory seems to be built up from segments having a limited number of erase
cycles. In order to spread out the erasure load on the memory, so called wear-leveling is needed.
Although it was not clear immediately, it was interesting to see how di_erent solutions came
about for this problem in a rather natural way. Real File Systems were developed, but controller
mechanism to be used with other File Systems also exist. This shows that the development of
technologies is not always dependent on who has the `best' technique, but also on the adaptability
and the size of the possible market.
Flash Databases - Sibren Polders & Lesley Van der Wee This presentation showed a
comparison between HDD and Flash Drives for execution time on query-answering. The
_rst type of test used a sequential search through the database. The second type used a B-tree
index. In the sequential search the execution time for the query (a simple select star from table
where key == value) was constant. For the indexed search the execution time was larger than the
sequential search after a certain amount of selectivity, which was bigger for Flash Memory as for
HDD. This indicates a better performance of the Flash Memory in read access. Overall the take
home message of the presenation was fairly simple.
Application of MapReduce in the Yahoo Data Center - Dominique Fonteyn This was a very
good presentation. It was very interesting to be introduced into the PigLatin language. Not
being a die-hard SQL'er it was very refreshing to see a more intuitive language for a step-by-step
datatransformation system, which incorporates a built-in distributed execution.
Comparison MapReduce and Parallel DB - Bart Ketelsleghers & Thomas De Craemer
This presentation gave a comparison between Parallel Databases and MapReduce. The results
showed that MapReduce didn't outperform the other parallel databases. What was interesting
though, is the fact that the presentation also gave information about the criticism by Google on
this comparison, showing that results in a paper do not always have to be blindly trusted. In a
sense researchers remain human trying to get into a good _eld of perception!
HadoopDB: marriage Parallel DB and MapReduce - Inneke Ponet & Bart Ketelsleghers
This presentation gave an overview over MapReduce, the parallel Databases as mentioned before
and their comparison. Eventually HadoopDB was explained as the combination of aspects of
MapReduce and the Parallel Databases. In a sense it was interesting to notice the idea of SQL
being translated to MapReduce jobs, each of which being the execution eventually of an SQL
query on the separate node of the cluster.
Network Dynamics: Structural Models - Lesley Van der Wee & Michael Mertens The
presentation focussed on structural models to explain cascading behavior in connected networks.
It was very interesting to see how a non-completely connected network can have e_ect on
the cascading behavior. The idea of heavily connected clusters blocking the cascade was very
insightfull, in a sense that it showed a possible extension for my own presentation, where the
model assumed a totally connected graph. Modelling the treshold inside these clusters would then
give a nice alternate view on the network-e_ect model that Wouter gave.