datastax

问题 I have a three nodes Cassandra Cluster and I have created one table which has more than 2,000,000 rows. When I execute this ( select count(*) from userdetails ) query in cqlsh, I got this error: OperationTimedOut: errors={}, last_host=192.168.1.2 When I run count function for less row or with limit 50,000 it works fine. 回答1: count(*) actually pages through all the data. So a select count(*) from userdetails without a limit would be expected to timeout with that many rows. Some details here:

问题 When I try to start Cassandra after patching my OS, I get this error: Exception (java.lang.AbstractMethodError) encountered during startup: org.apache.cassandra.utils.JMXServerUtils$Exporter.exportObject(Ljava/rmi/Remote;ILjava/rmi/server/RMIClientSocketFactory;Ljava/rmi/server/RMIServerSocketFactory;Lsun/misc/ObjectInputFilter;)Ljava/rmi/Remote; java.lang.AbstractMethodError: org.apache.cassandra.utils.JMXServerUtils$Exporter.exportObject(Ljava/rmi/Remote;ILjava/rmi/server

问题 I created a simple tabe: CREATE TABLE test ( "type" varchar, "value" varchar, PRIMARY KEY(type,value) ); I inserted 5 rows into it: INSERT INTO test(type,value) VALUES('test','tag1') INSERT INTO test(type,value) VALUES('test','tag2') INSERT INTO test(type,value) VALUES('test','tag3') INSERT INTO test(type,value) VALUES('test','tag4') INSERT INTO test(type,value) VALUES('test','tag5') I ran SELECT * from test LIMIT 3 and it works as expected. type | value ------+------ test | tag1 test | tag2

问题 We're planning on migrating our environment from Java 8 to OpenJDK 10. Doing this on my local machine, I've found that Cassandra will no longer start for me, giving the following error : I can't find any solid information online that says it is definitely not supported. This post from 4 months ago suggests that they do not support Java 10, but doesn't say it is confirmed, and is more inferred. There is also a comment on it from another user saying they have managed to get it running on Java

问题 I have a cassandra node at a machine. When I access cqlsh from the same machne it works properly. But when I tried to connect to it's cqlsh using "192.x.x.x" from another machine, I'm getting an error saying Connection error: ('Unable to connect to any servers', {'192.x.x.x': error(111, "Tried connecting to [('192.x.x.x', 9042)]. Last error: Connection refused")}) What is the reason for this? How can I fix it? 回答1: Probably the remote Cassandra node is not bound to the external network

问题 Here is what I am trying to do. I have created two nodes of DataStax enterprise cluster,on top of which I have created a java program to get the count of one table (Cassandra database table). This program was built in eclipse which is actually from a windows box. At the time of running this program from windows it's failing with the following error at runtime: Initial job has not accepted any resources; check your cluster UI to ensure that workers are registered and have sufficient memory The

问题 For my PoC, I am using spark-sql 2.4.x with Kafka. I have a streaming company data coming from Kafka topic. Company data Which has "company_id" ,"created_date" ,"field1" , "field2" and etc as fields. lets say this as newCompanyDataStream. I have old company data in my parquet file. i.e. "hdfs://parquet/company" , lets say this as oldCompanyDataDf. I need to check the new data stream from kafka (newCompanyDataStream) , for each received record of given company_id , if the data already there in

问题 I\'m writing Spark Jobs that talk to Cassandra in Datastax. Sometimes when working through a sequence of steps in a Spark job, it is easier to just get a new RDD rather than join to the old one. You can do this by calling the SparkContext [getOrCreate][1] method. Now sometimes there are concerns inside a Spark Job that referring to the SparkContext can take a large object (the Spark Context) which is not serializable and try and distribute it over the network. In this case - you\'re