VerdictDB: Universalizing Approximate Query Processing

Despite 25 years of research in academia, approximate query processing (AQP) has had little industrial adoption. One of the major causes of this slow adoption is the reluctance of traditional vendors to make radical changes to their legacy codebases, and the preoccupation of newer vendors (e.g., SQL-on-Hadoop products) with implementing standard features. Additionally, the few AQP engines that are available are each tied to a specific platform and require users to completely abandon their existing databases---an unrealistic expectation given the infancy of the AQP technology. Therefore, we argue that a universal solution is needed: a database-agnostic approximation engine that will widen the reach of this emerging technology across various platforms. Our proposal, called VerdictDB, uses a middleware architecture that requires no changes to the backend database, and thus, can work with all off-the-shelf engines. Operating at the driver-level, VerdictDB intercepts analytical queries issued to the database and rewrites them into another query that, if executed by any standard relational engine, will yield sufficient information for computing an approximate answer. VerdictDB uses the returned result set to compute an approximate answer and error estimates, which are then passed on to the user or application. However, lack of access to the query execution layer introduces significant challenges in terms of generality, correctness, and efficiency. This paper shows how VerdictDB overcomes these challenges and delivers up to 171$\times$ speedup (18.45$\times$ on average) for a variety of existing engines, such as Impala, Spark SQL, and Amazon Redshift, while incurring less than 2.6% relative error. VerdictDB is open-sourced under Apache License.Comment: Extended technical report of the paper that appeared in Proceedings of the 2018 International Conference on Management of Data, pp. 1461-1476. ACM, 201

Comparing diffraction from industry and transportation using NORD96, CNOSSOS-EU and NORD2000

Denne mastergraden sammenligner tre støyprediksjonsmetoder som fokuserer på diffraksjon med en enkelkants- og en dobbelkantsbarriere fra trafikk og industriell støy. De tre prediksjonsmetodene er den nordiske metoden fra 1996 (NORD96), den nye europeiske metoden (CNOSSOS-EU) og den nordiske metoden fra 2000 (NORD2000). De beregnede verdiene sammenlignes med diffraksjonsmålinger ved to barrierer. Det ene barrieren var en støyskjerm, og den andre var en bygning som henholdsvis gjenga enkelkants- og dobbelkantsdiffraksjon. Sammenlignet med lydtrykknivået og det kontinuerlige ekvivalente lydnivået mellom feltmålinger gir CNOSSOS-EU i gjennomsnitt mer nøyaktige beregninger. NORD96 ser ut til å gi akseptable resultater på enkelkantsdiffraksjon, men hadde tydelige avvik ved dobbeltkantsdiffraksjon. NORD2000 ga generelt et lavere lydtrykknivå sammenlignet med målte resultater. Denne oppgaven bidrar til et felt som trenger videre forskning og for å oppnå mer pålitelig resultater, er det flere forbedringer som kan gjøres.This master's thesis compares three noise prediction methods focusing on diffraction by a single-edge and a double-edge barrier, from road traffic and industrial noise. The three methods are the Nordic prediction method from 1996 (NORD96), the new standard European method (CNOSSOS-EU), and the Nordic prediction method from 2000 (NORD2000). The predicted values are compared from two diffraction measurements from two barriers. One was a screen, and another was a building that represented the single-edge and double-edge barrier, respectively. Comparing the sound pressure level and the continuous equivalent sound level between the field measurements and the prediction method, CNOSSOS-EU on average, gives more accurate predictions. NORD96 seem to give acceptable results on single-edge diffraction but had clear discrepancies at double-edge diffraction. Finally, NORD2000 gave, in general, a lower sound pressure level compared to measured results. This thesis contributes to a topic which requires further research and to obtain more reliable results; several improvements can be made

Genotipagem do SNP g. 10329T>C no gene estearoil-coa dessaturase (SCD1) relacionado a composição de ácidos graxos.

Os lipídios presentes na carne bovina possuem relação direta com a qualidade de carne, sendo responsáveis por conferir sabor e aroma. Além disso, a maior quantidade de ácidos graxos insaturados está ligada positivamente a saúde humana, reduzindo a incidência de doenças cardiovasculares, por exemplo. O gene SCD1 está localizado no cromossomo 26 de bovinos. O SNP g.10329T>C localizado no quinto éxon do gene, na posição 878pb da Open Read Frame, foi relacionado com aumento de ácidos graxos monoinsaturados e redução do ponto de fusão do tecido adiposo