bigdata

问题 Is there anyway to combine multiple CSV files together into a super file without using the read.csv/read_csv functions? I want to combine all the tables (CSV) in the folder into one csv file, since each of them represents a separate month. The folder looks like this: list.files(folder) [1] "2013-07 - Citi Bike trip data.csv" "2013-08 - Citi Bike trip data.csv" "2013-09 - Citi Bike trip data.csv" [4] "2013-10 - Citi Bike trip data.csv" "2013-11 - Citi Bike trip data.csv" "2013-12 - Citi Bike

问题 I've come across Fluentd. Why would you use such a thing when its easy enough to store raw data on a db directly? I might be misunderstanding the use of the technology here. Glad to hear some feedback. Why would anyone want to go through another layer, when its easy enough to capture and store raw data in your own a data store? Consider this scenario. I want to store page views. Raw data is stored in an RDBMS and formatted data is stored in Mongodb This is a short description of my current

问题 I know how to use pandas to read files with CSV extension. When reading a large file i get an out of memory error. The file is 3.8 million rows and 6.4 millions columns file. There is mostly genome data in the file of large populations. How can I overcome the problem, what is standard practice and how do I select the appropriate tool for this. Can I process a file this big with pandas, or there is another tool? 回答1: You can use Apache Spark to distribute in-memory processing of csv files

问题 I'm trying to setup an Hadoop 3 cluster. Two questions about the Erasure Coding feature : How I can ensure that erasure coding is enabled ? Do I still need to set the replication factor to 3 ? Please indicate the relevant configuration properties related to erasure coding/replication, in order to get the same data security as Hadoop 2 (replication factor 3) but with the disk space benefits of Hadoop 3 erasure coding (only 50% overhead instead of 200%). 回答1: In Hadoop3 we can enable Erasure

问题 I am trying to emulate pagination in BigQuery by grabbing a certain row number using an offset. It looks like the time to retrieve results steadily degrades as the offset increases until it hits ResourcesExceeded error. Here are a few example queries: Is there a better way to use the equivalent of an "offset" with BigQuery without seeing performance degradation? I know this might be asking for a magic bullet that doesn't exist, but was wondering if there are workarounds to achieve the above.

问题 I am using sqoop to import data from oracle 11g, as i do not have the permission to put the ojdbc jar in sqoop's lib on cluster i am explicitly providing the jar using -libjars but it is throwing exception.The code I have used is : sqoop eval -libjars /root/shared_folder/ojdbc6.jar --driver oracle.jdbc.OracleDriver --connect jdbc:oracle:thin:@127.0.0.1:1521:XE --username srivastavaaman --password manager --query 'SELECT * from TestTable1' The output that follows is : Warning: /usr/lib/sqoop/.

问题 I've read a lot of articles recently about populating a grails table from huge data, but seem to have hit a ceiling. My code is as follows: class LoadingService { def sessionFactory def dataSource def propertyInstanceMap = org.codehaus.groovy.grails.plugins.DomainClassGrailsPlugin.PROPERTY_INSTANCE_MAP def insertFile(fileName) { InputStream inputFile = getClass().classLoader.getResourceAsStream(fileName) def pCounter = 1 def mCounter = 1 Sql sql = new Sql(dataSource) inputFile.splitEachLine(/

问题 why ssh login is required before starting hadoop? And why hadoop asks for password for starting any of the services? shravilp@shravilp-HP-15-Notebook-PC:~/hadoop-2.6.3$ sbin/start-all.sh This script is Deprecated. Instead use start-dfs.sh and start-yarn.sh Starting namenodes on [localhost] shravilp@localhost's password: localhost: starting namenode, logging to /home/shravilp/hadoop- 回答1: In Ubuntu, you can use the following one time set up steps to eliminate the need to enter password when

问题 This question already has answers here : How to join (merge) data frames (inner, outer, left, right) (13 answers) Closed 3 years ago . edit: Sorry y'all, I didn't mean to repost a question. The issue I'm having isn't just with joining two tables, it's joining two tables with a column that isn't exactly the same in both tables (I updated the sample data to illustrate this). That is, I want to pmatch, or str_detect the strings within the Test.Takers$First column with the Every.Student.In.The

问题 Let me explain the problem. I have this line of code: u = FOREACH persons GENERATE FLATTEN($0#'experiences') as j; dump u; which produces this output: ([id#1,date_begin#12 2012,description#blabla,date_end#04 2013],[id#2,date_begin#02 2011,description#blabla2,date_end#04 2013]) ([id#1,date_begin#12 2011,description#blabla3,date_end#04 2012],[id#2,date_begin#02 2010,description#blabla4,date_end#04 2011]) Then, when I do this: p = foreach u generate j#'id', j#'description'; dump p; I have this