Why does Spark only lazily calculate RDD? Why is it really calculated only when it is used in an action operation for the first time?
Why does Spark only lazily calculate RDD? Why is it really calculated only when it is used in an action operation for the first time?
Computing resources are so precious, why do useless calculations?
not only is the computing resource valuable, but what I think is more important is that spark has a concept of pipeline and DAG.
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what is the process of running start-all to start a spark cluster? ...
how to understand the content of the green part? Why does it feel so awkward? the feeling in the book is also very vague. ...
val lines: Dataset[String] = session.read.textFile("") val words: Dataset[String] = lines.flatMap(_.split(" ")) linesdataSetflatMapdataSetIDEAflatMap: def flatMap[U : Encoder](func: T => Traversabl...
use spark mllib linear regression to do traffic forecast printing training, weight and other coefficients are all NaN data format: 520221 | 0009 | 0009 | 292 | 000541875150 | 2018 | 04 | 18 | 11 | 3 | 137 520626 | 0038 | 0038 | 520626 | 2030300010...
1Query spark0-2 the three hosts are zookeeper clusters 2 spark0-4 five hosts are spark clusters 3 spark0-1 two hosts achieve master high availability. run start-all.sh on spark0 to start the spark cluster. At this point, spark will be launched nat...
suppose there are ten partitions in a RDD. When you groupby this RDD, you get a new RDD,. Is the data of the same field in the same partition? my test results show that data from the same grouping field is divided into the same partition, and data fro...
ask Spark DataFrame to edit only one column (intercept a paragraph) and return a new DataFrame ...
started spark,hdfs,yarn successfully at first, but after a long time, it was found that the spark task could not be submitted normally, and there was always an error similar to the following. "INFO Client: Retrying connect to server: 0.0.0.0 Already tr...
refer to the link description to run the tutorial code in the web notebook provided by the zeppelin container. Import local file: val bankText = sc.textFile("D: Projects Zeppelin bank bank-full.csv") case class Bank(age:Integer, job:Stri...
are there any open source middleware products that provide traffic marking and traffic distribution? that is, when a http request comes, you can route the request to the specified machine or environment according to the information of various dimension...
Dataset<Row> df = spark.read().format("csv").load("C: develop intellij-workspace SparkSqlDemos resources down.csv"); df.createOrReplaceTempView("down"); Dataset<Row> dfSQL = spark.sql("SELECT ...
I use IntelliJ IDEA locally for spark development and report an error when submitting it to the cluster to run. After searching, all the answers point to insufficient CPU memory resources, but I have set up enough CPU memory resources, and the state o...
the figure is as follows: def update_model(rdd),mixture_model: it s OK to declare mixture_model directly in update_model, but every time you foreachRDD, you need to re-declare MingleModel. Makes it impossible to update the model in real time ...
configure spark s environment according to this link https: blog.csdn.net w417950., but will report an error when starting: I searched for it and didn t find a way to solve my problem. Beginners on the road, please forgive me ...
Slaves had registered, but cannot pass work to slave. (Standalone) If I open all of the Inbound TCP port, it can work. But I cannot do it, because it is about security. 2018-06-04 13:22:44 INFO DAGScheduler:54 - Submitting 100 missing tasks from...
< H2 > Business scenario < H2 > A large number of json files need to be read and re-parsed and imported into elasticsearch . Json files are saved in different date folders. The size of a single folder is about 80g. The number of json files under the ...
problem description Hi, I called the jieba participle when I was running pyspark on the company line, and found that I could successfully import, but when I called the participle function in RDD, it suggested that there was no module jieba, without th...
1. Json data is now available as follows { "id ": 11, "data ": [{ "package ": "com.browser1 ", "activetime ": 60000}, { "package ": "com.browser6 ", "activetime ": 1205000}, { "package ": "com.browser7 ", "activetime ": 1205000}]} { "id ": 12...
purpose: there are two large pieces of data in spark that require join,. Both input data contain the field userid. Now you need to associate them according to userid. I hope to avoid shuffle. completed: I pre-processed two pieces of data into 1w f...
I have a batch of data (10 billion) as follows, ID FROM TO 1 A B 2 A C 3 B A 4 C A Delete duplicate two-way relational data as follows ID FROM TO 1 A B 2 A C 1. Because the amount of data is too large, bloomfilter is no...