Hadoop Perfect File: A fast and memory-efficient metadata access archive file to face small files problem in HDFS

HDFS faces several issues when it comes to handling a large number of small files. These issues are well addressed by archive systems, which combine small files into larger ones. They use index files to hold relevant information for retrieving a small file content from the big archive file. However, existing archive-based solutions require significant overheads when retrieving a file content since additional processing and I/Os are needed to acquire the retrieval information before accessing the actual file content, therefore, deteriorating the access efficiency. This paper presents a new archive file named Hadoop Perfect File (HPF). HPF minimizes access overheads by directly accessing metadata from the part of the index file containing the information. It consequently reduces the additional processing and I/Os needed and improves the access efficiency from archive files. Our index system uses two hash functions. Metadata records are distributed across index files using a dynamic hash function. We further build an order-preserving perfect hash function that memorizes the position of a small file's metadata record within the index file.The authors thank the anonymous reviewers for their insightful suggestions. This work is supported by the National Natural Science Foundation of China (Grant No. 61602037 )

Mountain Apiculture and Environmental Dynamics: Impact of Climate Variability on Bee Farming in OKU, CAMEROON.

This study aims at analyzing the effects of climate variability on bee farming in Mount Oku. The guiding premise is that climate variability has brought about environmental changes causing a fall in the quantity and quality of honey. A mixed research approach was adopted in collecting data. Questionnaires were administered to 90 purposively selected bee farmers and interviews conducted with key actors in honey production. SPSS, version 20.0 was used to analyze data while the cumulative difference index helped establish climatic anomalies and trends. Findings revealed falling rainfall trends with marked seasonal variations. Temperatures show a rising trend with little but sensitive anomalies. This has affected periods of flowering for bee plants as acknowledged by 97% of bee farmers. Hive colonization rate has been decreasing (74% - 55%), with an increasing rate of abscond (34% -46%), resulting in a reduction in honey yields. Climate variability has increased the magnitude of other environmental stressors such as bush fires and forest degradation, while reducing the growing period of some bee plants. The coping strategies put in place by bee farmers are limited and policies need to address this situation so as to maintain the quality of OKU honey

Households’ Assets Dynamics and Ecotourism Choices in the Western Highlands of Cameroon

Ecotourism is increasingly accepted as a suitable alternative for sustaining rural livelihoods. In spite of this trend, quantitative assessments of relationships between household assets and ecotourism choices, and the policy implications thereof, currently account for only a negligible number of studies in sub-Saharan Africa. This paper contributes to this evidence gap by analyzing the extent to which households’ assets drive ecotourism choices on a representative sample of 200 households in Cameroon. The Principal Component Analysis (PCA) and the Human Development Index (HDI) were used to construct indices for ecotourism choices. The ordinary least square and logit models were also employed to estimate the effect of various household assets on ecotourism choices. A high preference was observed for the production and sale of arts and crafts items and the promotion of cultural heritage sites as key ecotourism choices. More women are found to participate in conservation education, as opposed to culture-related activities such as arts and crafts. Access to education and training were inversely related to cultural festival promotion. The results suggest the need to: (i) stem the overdependence on conservation sites for wood supply to the arts and crafts sector, (ii) enforce endogenous cultural institutional regulations, including those that increase female participation in guiding future ecotourism choices. This paper contributes to ecotourism development and conservation theory, with regards to unbundling household level predictors of ecotourism choices, and has implications on the design of policies to implement environmentally less-demanding ecotourism activities