nosql | 易学教程

Only date range scanning Cassandra CQL timestamp

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问题 I have a table like given below. CREATE TEST( HOURLYTIME TIMESTAMP, FULLTIME TIMESTAMP, DATA TEXT, PRIMARY KEY(HOURLYTIME,FULLTIME) ) I inserted the record (2014-12-12 00:00:00,2014-12-12 00:00:01,'Hello World') I would like to search based on date time range in HOURLYTIME field which holds hourly records.When i tried with token() like select * from TEST where token(HOURLYTIME)=token('2014-12-12') to get all the records for that date it returns only for one hour record i.e for 2014-12-12 **00

When does Cassandra DB index data after updating a column as secondary index

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问题 I've a created a secondary index by using update column ... from cassandra-cli , then I tested by using commnand get User where code = 'MX' , code was the column I put as index, this command just returns data inserted after index creation, but data before is not returned , I thought that previous data would be indexed too , anyone has a clue? thanks in advance 回答1: In Cassandra, secondary index starts working only after it is being created. Go through the SecondaryIndex class in apache

Cassandra Database Data Model: Critic my schema design

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问题 I need to implement a database for a testing system. It is designed to store test data for future statistical analysis. It has to be Cassandra based. I've designed a schema, but since this is my first attempt at NoSQL design, I would like to get some feedback. I will first describe the data I wish to save, then describe two basic queries and finally present my suggested design. I intend on using Cassandra 1.1 so I tried to use Composite Columns in my design, however, feel free to suggest

Does the Couchbase REST API support NON-JSON data (binary data)

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问题 I am storing c structures to couchbase, I am doing so so that I can read back these structures later and process directly, I am avoiding the steps of 1 )C structure - > JSON while storing and 2 )JSON -> C structure while retrieving. This is working well when I use lcb_get() and lcb_set() But I also need have a requirement for making hits to views using the REST model and lcb_make_http_request () call. So I was wondering how the lcb_make_http_request () will handle my non-JSON C structure ,

Scaling temporary records in database to count totals to stop over-subscribing

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问题 I'm looking at a system where people RSVP to a free web conference, these web conferences can get really busy with a lot of interest and there are limited places, so there has to be some way to ensure it doesn't get over-subscribed... So, we need to have a countdown from the time they book their seat to the time that their order is completed and confirmed. This way it's the first X amount of people to actually click 'Attending' that get the seats for the conference. If the user does not

Create a table in Cassandra 1.2 with CQL3 where column names will be created at runtime

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问题 I want to store snapshots of an object in Apache Cassandra 1.2 Row key is the Object#ID and there will be a column for each snapshot. -------- latest -------- v2 -------- v1 id-122 100 -------- 50 -------- 66 -------- So column names are created dynamically at runtime. How to create the previous table in Cassandra 1.2 using CQL3 ? 回答1: You would use the compound primary key feature of CQL3: CREATE TABLE foo ( object_id int, version int, value int, PRIMARY KEY (object_id, version)); 回答2: In

图形数据库、NOSQL和Neo4j

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简介在众多不同的数据模型里，关系数据模型自80年代就处于统治地位，而且有不少实现，如 Oracle 、 MySQL 和 MSSQL ，它们也被称为关系数据库管理系统（RDBMS）。然而，最近随着关系数据库使用案例的不断增加，一些问题也暴露了出来，这主要是因为两个原因：数据建模中的一些缺陷和问题，以及在大数据量和多服务器之上进行水平伸缩的限制。两个趋势让这些问题引起了全球软件社区的重视：在应对这些趋势时，关系数据库产生了更多的问题。这导致大量解决这些问题某些特定方面的不同技术的出现，它们可以与现有RDBMS相互配合或代替它们 - 亦被称为混合持久化（Polyglot Persistence）。数据库替代品并不是新鲜事物，它们已经以对象数据库（OODBMS）、层次数据库（如LDAP）等形式存在很长时间了。但是，过去几年间，出现了大量新项目，它们被统称为NOSQL数据库（NOSQL-databases）用户、系统和传感器产生的数据量呈指数增长，其增长速度因大部分数据量集中在象Amazon、Google和其他云服务这样的分布式系统上而进一步加快。数据内部依赖和复杂度的增加，这一问题因互联网、Web2.0、社交网络，以及对大量不同系统的数据源开放和标准化的访问而加剧。本文旨在介绍图形数据库（Graph Database）在NOSQL运动里的地位

In MongoDB, how does on get the value in a field for an embedded document, but query based on a different value

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问题 I have a basic structure like this: > db.users.findOne() { "_id" : ObjectId("4f384903cd087c6f720066d7"), "current_sign_in_at" : ISODate("2012-02-12T23:19:31Z"), "current_sign_in_ip" : "127.0.0.1", "email" : "something@gmail.com", "encrypted_password" : "$2a$10$fu9B3M/.Gmi8qe7pXtVCPu94mBVC.gn5DzmQXH.g5snHT4AJSZYCu", "last_sign_in_at" : ISODate("2012-02-12T23:19:31Z"), "last_sign_in_ip" : "127.0.0.1", "name" : "Trip Jameson", "sign_in_count" : 100, "usertimes" : [ ...thousands and thousands of

Access subcollection in mongoid with rails form to edit and create new entry

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问题 I am using mongodb with mongoid in rails3. I am newbie to all this. My models are as shown below. class Californium include Mongoid::Document field :first_name field :License_type Field :Licese_expiry_date embeds_one :address end class Address include Mongoid::Document field :street field :city field :state field :zip embedded_in :Californium, :inverse_of => :address end My Controller class CaliforniaController < ApplicationController def index @california = Californium.all respond_to do

When to replace RDBMS/ORM with NoSQL/DocumentStore

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问题 I've looked at MongoDB/norm (but want a general document-oriented store answer). It seems really nice to work with and I'm interested in knowing when it should be used instead of RDBMS+ORM? What should i use for for instance: Stackoverflow similiar sites Social communities forums (I posted another more general question but it got a splendid answer that might be interesting for others, hence the new question) 回答1: All of the examples you mentioned can be built using a document store. Whether