cassandra

问题 My main question is what is the benefit of integrating Cassandra and Elasticsearch versus using only Elasticsearch? In fact, there are answers to similar questions on StackOverflow (e.g., here and here). But there are some points: A lot of answers are old. Much may have changed in these years. One point that is mentioned is that "Sometimes ElasticSearch loses writes". However, it can be imagined those alleged loses may had been because of some bugs that have been solved in these years. It is

问题 I would like to not start the spider job if the external depended APIs(cassandra, mysql etc) are not reachable classHealthCheck: @staticmethod def is_healthy(): config = json.loads(configHelper.get_data()) cassandra_config = config['cassandra'] cluster = Cluster(cassandra_config['hosts'], port=cassandra_config['port']) session = cluster.connect(cassandra_config['keyspace']) try: session.execute('SELECT 1') except Exception as e: logging.error(e) return True I can invoke the is_healthy inside

问题 I want to connect to cassandra but got this error: $ bin/cqlsh Connection error: ('Unable to connect to any servers', {'192.168.1.200': error(10061, "Tried connecting to [('192.168.1.200', 9042)]. Last error: No connection could be made because the target machine actively refused it")}) 回答1: Pretty simple. The machine is actively refusing it because your system does not have cassandra running on it. Follow the following steps to completely get rid of this trouble : Install Cassandra from

问题 Can someone explain in simple terms what is the static column in Cassandra, and its use? I came across this link Static column, but wasn't able to understand it much. Thanks 回答1: Static column is a way to associate data with the whole partition, so it will be shared between all rows inside that partition. There are legitimate cases, when all rows need to have the same data, and when data is updated, we won't need to update every row. One example that comes in mind is e-commerce. For example,

问题 I have a table like this in Scylladb. To make it clear I have removed lot of columns from below table but in general this table has ~25 columns total. CREATE TABLE testks.client ( client_id int, lmd timestamp, cola list<text>, colb list<text>, colc boolean, cold int, cole int, colf text, colg set<frozen<colg>>, colh text, PRIMARY KEY (client_id, lmd) ) WITH CLUSTERING ORDER BY (lmd DESC) AND bloom_filter_fp_chance = 0.01 AND caching = {'keys': 'ALL', 'rows_per_partition': 'ALL'} AND comment =

问题 I've been working with Cassandra for a little while and now I'm trying to setup spark and spark-cassandra-connector. I'm using IntelliJ IDEA to do that (first time with IntelliJ IDEA and Scala too) in Windows 10. build.gradle apply plugin: 'scala' apply plugin: 'idea' apply plugin: 'eclipse' repositories { mavenCentral() flatDir { dirs 'runtime libs' } } idea { project { jdkName = '1.8' languageLevel = '1.8' } } dependencies { compile group: 'org.apache.spark', name: 'spark-core_2.11',

问题 I am using Cassandra's insert JSON feature to insert data into the table. In the JSON that I create, I do not include the null values. Meaning, ignore the fields that have null values in it. Does Cassandra create tombstones in such cases, if I am inserting the record say, for the first time? I assume for subsequent upsert for the same key will create tombstone. Is that right? 回答1: Cell tombstone should still get created for the values which are not included in the json you are trying to

问题 I know it can be done in traditional way, but if I were to use Cassandra DB, is there a easy/quick and agaile way to add csv to the DB as a set of key-value pairs ? Ability to add a time-series data coming via CSV file is my prime requirement. I am ok to switch to any other database such as mongodb, rike, if it is conviniently doable there.. 回答1: Edit 2 Dec 02, 2017 Please use port 9042. Cassandra access has changed to CQL with default port as 9042, 9160 was default port for Thrift. Edit 1

问题 I know it can be done in traditional way, but if I were to use Cassandra DB, is there a easy/quick and agaile way to add csv to the DB as a set of key-value pairs ? Ability to add a time-series data coming via CSV file is my prime requirement. I am ok to switch to any other database such as mongodb, rike, if it is conviniently doable there.. 回答1: Edit 2 Dec 02, 2017 Please use port 9042. Cassandra access has changed to CQL with default port as 9042, 9160 was default port for Thrift. Edit 1

问题 I am new to cassandra and I read some articles about static and dynamic column family. It is mentioned ,From Cassandra 3 table and column family are same. I created key space, some tables and inserted data into that table. CREATE TABLE subscribers( id uuid, email text, first_name text, last_name text, PRIMARY KEY(id,email) ); INSERT INTO subscribers(id,email,first_name,last_name) VALUES(now(),'Test@123.com','Test1','User1'); INSERT INTO subscribers(id,email,first_name,last_name) VALUES(now(),