key-value-store

问题 I am new to zookeeper and distributed systems, and am learning it myself. From what I understand for now, it seems that ZooKeeper is simply a key-value store whose keys are paths and values are strings, which is nothing different from, say, Redis. (And apparently we can use slash-separated path as keys in redis as well.) So my question is, what is the essential difference between ZooKeeper and other distributed KV store? Why is ZooKeeper using so called "paths" as keys, instead of simple

问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 2 years ago . Berkeley DB (JE) licensing may be a deal killer. I have a Java application going to a small set of customers but as it is a desktop application, my price cannot support individual instance licensing. Is there a recommended Java alternative to Berkeley DB? Commercial or otherwise (good key-value store

问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 2 years ago . Berkeley DB (JE) licensing may be a deal killer. I have a Java application going to a small set of customers but as it is a desktop application, my price cannot support individual instance licensing. Is there a recommended Java alternative to Berkeley DB? Commercial or otherwise (good key-value store

问题 I am trying to map a existing relational database to a key value store. Couple of example tables are represented below. For an instance the above "Employee Details" table can be represented as follows in Redis (or any similiar key-value store) set emp_details.first_name.01 "John" set emp_details.last_name.01 "Newman" set emp_details.address.01 "New York" set emp_details.first_name.02 "Michael" set emp_details.last_name.02 "Clarke" set emp_details.address.02 "Melbourne" set emp_details.first

问题 Say I have a simple table that contains username, firstname, lastname. How do I express this in berkeley Db? I'm currently using bsddb as the interface. Cheers. 回答1: You have to pick one "column" as the key (must be unique; I imagine that would be "username" in your case) -- the only way searches will ever possibly happen. The other columns can be made to be the single string value of that key by any way you like, from pickling to simple joining with a character that's guaranteed to never

问题 Closed. This question is off-topic. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 4 years ago . Anybody know of a lightweight yet durable database, written in Javascript, that can be used with Node.js. I don't want the 'weight' of (great) solutions like Mongo or Couch. A simple, in memory JS database with the capability to persist to disk as a file would be enough. I would only use it to store small

问题 I know that the order of the keys is not guaranteed and that's OK, but what exactly does it mean that the order of the values is not guaranteed as well * ? For example, I am representing a matrix as a dictionary, like this: signatures_dict = {} M = 3 for i in range(1, M): row = [] for j in range(1, 5): row.append(j) signatures_dict[i] = row print signatures_dict Are the columns of my matrix correctly constructed? Let's say I have 3 rows and at this signatures_dict[i] = row line, row will

问题 Imagine you have a table 'users' with 10 Mio records and a table 'groups' with 1 mio records. In average you have 50 users per group which I would store at least in an rdbms in a table called users2groups. users2groups is in fact a sparse matrix. Only 80% of the full dataset of users and groups fit into available memory. The data for the group membership (users2groups) comes on top, so that if memory is needed to cache group memberships this has to be deallocated from either the users or the

问题 I have an application with a high load for batch read operations. My Aerospike cluster (v 3.7.2) has 14 servers, each one with 7GB RAM and 2 CPUs in Google Cloud. By looking at Google Cloud Monitoring Graphs, I noticed a very unbalanced load between servers: some servers have almost 100% CPU load, while others have less than 50% (image below). Even after hours of operation, the cluster unbalanced pattern doesn't change. Is there any configuration that I could change to make this cluster more

问题 I have a dictionary with values as lists of text values. (ID : [text values]) Below is an excerpt. data_dictionary = { 52384: ['text2015', 'webnet'], 18720: ['datascience', 'bigdata', 'links'], 82465: ['biological', 'biomedics', 'datamining', 'datamodel', 'semantics'], 73120: ['links', 'scientometrics'], 22276: ['text2015', 'webnet'], 97376: ['text2015', 'webnet'], 43424: ['biological', 'biomedics', 'datamining', 'datamodel', 'semantics'], 23297: ['links', 'scientometrics'], 45233: ['webnet',