partitioning

问题 I'm having trouble with spatial partitioning for my class. The problem I'm having is implementing the Quadtree in C++ using DirectX. I get the concept behind it but the coding to implement it is what I'm having trouble with. Right now I have the environment to test the tree. And the structure for the tree. struct Node { vector3 element; Node* left, right; }; Node root; 来源： https://stackoverflow.com/questions/5994778/how-to-implement-a-quadtree-for-spatial-partitioning

问题 I'm actually using local partitioning to export customer table that has 100K rows to multiple XML files ( as i can't export data to one file because StaxEventItemWriter<T> isn't Thread-safe) but i don't get better results with multiple Threads even when increasing gridSize to 10. I think the problem in the StaxEventItemWriter because i have some code errors like : java.lang.NullPointerException: null at com.sun.xml.internal.stream.writers.XMLStreamWriterImpl.flush(XMLStreamWriterImpl.java:397

问题 I'm actually using local partitioning to export customer table that has 100K rows to multiple XML files ( as i can't export data to one file because StaxEventItemWriter<T> isn't Thread-safe) but i don't get better results with multiple Threads even when increasing gridSize to 10. I think the problem in the StaxEventItemWriter because i have some code errors like : java.lang.NullPointerException: null at com.sun.xml.internal.stream.writers.XMLStreamWriterImpl.flush(XMLStreamWriterImpl.java:397

问题 I have data partitioned in one way, I just want to partition it in another. So it basically gonna be something like this: sqlContext.read().parquet("...").write().partitionBy("...").parquet("...") I wonder does this will trigger shuffle or all data will be re-partition locally, because in this context a partition means just a directory in HDFS and data from the same partition doesn't have to be on the same node to be written in the same dir in HDFS. 回答1: Neither parititionBy nor bucketBy

问题 Here is the code that I came up with: static void findNumbers(int[] list, int index, int current, int goal, String result) { if (list.length < index || current>goal) return; for (int i = index; i < list.length; i++) { if (current + list[i] == goal) { System.out.println(result + " " + String.valueOf(list[i])); } else if (current + list[i] < goal) { findNumbers(list, i + 1, current + list[i], goal, result + " " + String.valueOf(list[i])); } } } Call it using: findNumbers(array, starting_index,

问题 I have situation, where running a query that filters by an indexed column in a partitioned table, performs a full table scan. Apparently , this is a known issue in postgresql, and it's explained in detail here. Is there a more elegant way around this other than performing a query on each partition, and then performing a UNION on all of the results? 回答1: Indexes work just fine to do a scan only of the relevant partitions in PostgreSQL. But, you have to set everything up properly for it to work

问题 I have situation, where running a query that filters by an indexed column in a partitioned table, performs a full table scan. Apparently , this is a known issue in postgresql, and it's explained in detail here. Is there a more elegant way around this other than performing a query on each partition, and then performing a UNION on all of the results? 回答1: Indexes work just fine to do a scan only of the relevant partitions in PostgreSQL. But, you have to set everything up properly for it to work

问题 I'm trying to do a 10-fold cross validation for some glm models that I have built earlier in R. I'm a little confused about the cv.glm() function in the boot package, although I've read a lot of help files. When I provide the following formula: library(boot) cv.glm(data, glmfit, K=10) Does the "data" argument here refer to the whole dataset or only to the test set? The examples I have seen so far provide the "data" argument as the test set but that did not really make sense, such as why do 10

问题 I only have access to oracle standard edition, which feature of oracle standard edition provides the functionality like that of partitioning is there any concept of logically merging table like that in MYSQL. 回答1: Only thing that comes to mind is to have a real table for each 'partition', and then a view than unions them all together. But you'd have to rebuild the view every time you added or removed a 'partition', and there might be performance issues, as well as potential complication with

问题 I only have access to oracle standard edition, which feature of oracle standard edition provides the functionality like that of partitioning is there any concept of logically merging table like that in MYSQL. 回答1: Only thing that comes to mind is to have a real table for each 'partition', and then a view than unions them all together. But you'd have to rebuild the view every time you added or removed a 'partition', and there might be performance issues, as well as potential complication with