partitioning

which algorithm can do a stable in-place binary partition with only O(N) moves?

我怕爱的太早我们不能终老 提交于 2019-11-27 02:09:02
问题 I'm trying to understand this paper: Stable minimum space partitioning in linear time. It seems that a critical part of the claim is that Algorithm B sorts stably a bit-array of size n in O(nlog 2 n) time and constant extra space, but makes only O(n) moves. However, the paper doesn't describe the algorithm, but only references another paper which I don't have access to. I can find several ways to do the sort within the time bounds, but I'm having trouble finding one that guarantees O(N) moves

Handling very large data with mysql

≯℡__Kan透↙ 提交于 2019-11-26 23:57:45
问题 Sorry for the long post! I have a database containing ~30 tables (InnoDB engine). Only two of these tables, namely, "transaction" and "shift" are quite large (the first one have 1.5 million rows and shift has 23k rows). Now everything works fine and I don't have problem with the current database size. However, we will have a similar database (same datatypes, design ,..) but much larger, e.g., the "transaction" table will have about 1 billion records (about 2,3 million transaction per day) and

How does partitioning work in Spark?

主宰稳场 提交于 2019-11-26 23:02:16
问题 I'm trying to understand how partitioning is done in Apache Spark. Can you guys help please? Here is the scenario: a master and two nodes with 1 core each a file count.txt of 10 MB in size How many partitions does the following create? rdd = sc.textFile(count.txt) Does the size of the file have any impact on the number of partitions? 回答1: By default a partition is created for each HDFS partition, which by default is 64MB (from the Spark Programming Guide). It's possible to pass another

Default Partitioning Scheme in Spark

巧了我就是萌 提交于 2019-11-26 21:01:06
When I execute below command: scala> val rdd = sc.parallelize(List((1,2),(3,4),(3,6)),4).partitionBy(new HashPartitioner(10)).persist() rdd: org.apache.spark.rdd.RDD[(Int, Int)] = ShuffledRDD[10] at partitionBy at <console>:22 scala> rdd.partitions.size res9: Int = 10 scala> rdd.partitioner.isDefined res10: Boolean = true scala> rdd.partitioner.get res11: org.apache.spark.Partitioner = org.apache.spark.HashPartitioner@a It says that there are 10 partitions and partitioning is done using HashPartitioner . But When I execute below command: scala> val rdd = sc.parallelize(List((1,2),(3,4),(3,6))

How to understand the dynamic programming solution in linear partitioning?

大城市里の小女人 提交于 2019-11-26 17:34:48
问题 I'm struggling to understand the dynamic programming solution to linear partitioning problem. I am reading the The Algorithm Design Manual and the problem is described in section 8.5. I've read the section countless times but I'm just not getting it. I think it's a poor explanation (the what I've read up to now has been much better), but I've not been able to understand the problem well enough to look for an alternative explanation. Links to better explanations welcome! I've found a page with

How to find all partitions of a set

女生的网名这么多〃 提交于 2019-11-26 15:21:05
I have a set of distinct values. I am looking for a way to generate all partitions of this set, i.e. all possible ways of dividing the set into subsets. For instance, the set {1, 2, 3} has the following partitions: { {1}, {2}, {3} }, { {1, 2}, {3} }, { {1, 3}, {2} }, { {1}, {2, 3} }, { {1, 2, 3} }. As these are sets in the mathematical sense, order is irrelevant. For instance, {1, 2}, {3} is the same as {3}, {2, 1} and should not be a separate result. A thorough definition of set partitions can be found on Wikipedia . I've found a straightforward recursive solution. First, let's solve a

LINQ Partition List into Lists of 8 members [duplicate]

醉酒当歌 提交于 2019-11-26 13:29:44
This question already has an answer here: Split List into Sublists with LINQ 27 answers How would one take a List (using LINQ) and break it into a List of Lists partitioning the original list on every 8th entry? I imagine something like this would involve Skip and/or Take, but I'm still pretty new to LINQ. Edit: Using C# / .Net 3.5 Edit2: This question is phrased differently than the other "duplicate" question. Although the problems are similar, the answers in this question are superior: Both the "accepted" answer is very solid (with the yield statement) as well as Jon Skeet's suggestion to

How to partition an array of integers in a way that minimizes the maximum of the sum of each partition?

自闭症网瘾萝莉.ら 提交于 2019-11-26 12:45:41
问题 The inputs are an array A of positive or null integers and another integer K. We should partition A into K blocks of consecutive elements (by \"partition\" I mean that every element of A belongs to some block and 2 different blocks don\'t contain any element in common). We define the sum of a block as sum of the elements of the block. The goal is to find such a partition in K blocks such that the maximum of the sums of each block (let\'s call that \" MaxSumBlock \") is minimized. We need to

How to optimize partitioning when migrating data from JDBC source?

雨燕双飞 提交于 2019-11-26 12:32:37
I am trying to move data from a table in PostgreSQL table to a Hive table on HDFS. To do that, I came up with the following code: val conf = new SparkConf().setAppName("Spark-JDBC").set("spark.executor.heartbeatInterval","120s").set("spark.network.timeout","12000s").set("spark.sql.inMemoryColumnarStorage.compressed", "true").set("spark.sql.orc.filterPushdown","true").set("spark.serializer", "org.apache.spark.serializer.KryoSerializer").set("spark.kryoserializer.buffer.max","512m").set("spark.serializer", classOf[org.apache.spark.serializer.KryoSerializer].getName).set("spark.streaming

Determining optimal number of Spark partitions based on workers, cores and DataFrame size

核能气质少年 提交于 2019-11-26 12:09:53
问题 There are several similar-yet-different concepts in Spark-land surrounding how work gets farmed out to different nodes and executed concurrently. Specifically, there is: The Spark Driver node ( sparkDriverCount ) The number of worker nodes available to a Spark cluster ( numWorkerNodes ) The number of Spark executors ( numExecutors ) The DataFrame being operated on by all workers/executors, concurrently ( dataFrame ) The number of rows in the dataFrame ( numDFRows ) The number of partitions on