Lots of reads in every query, fewer regular writes Both databases perform well on reads where the hot data set fits in memory. Both also emphasize join-less data models (and encourage denormalization instead), and both provide indexes on documents or rows, although MongoDB’s indexes are currently more flexible. Cassandra’s storage engine provides constant-time writes no … Read more
I remembered seeing someone answer this question in the Cassandra user mailing list a short while back, but I cannot find the exact message right now. Ironically, Cassandra Evangelist Rebecca Mills just posted an article that addresses this issue (Things you should be doing when using Cassandra drivers…points #13 and #22). But the answer is … Read more
org.apache.spark.Logging is available in Spark version 1.5.2 or lower version. It is not in the 2.0.0. Pls change versions as follows <dependency> <groupId>org.apache.spark</groupId> <artifactId>spark-streaming_2.11</artifactId> <version>1.5.2</version> </dependency> <dependency> <groupId>org.apache.spark</groupId> <artifactId>spark-core_2.10</artifactId> <version>1.5.2</version> </dependency> <dependency> <groupId>org.apache.spark</groupId> <artifactId>spark-sql_2.10</artifactId> <version>1.5.2</version> </dependency> <dependency> <groupId>org.apache.spark</groupId> <artifactId>spark-streaming-kafka-0-8_2.11</artifactId> <version>1.6.2</version> </dependency>
You are running into CASSANDRA-11850, where cqlsh breaks with Python 2.7.11+. This ticket has been marked as “Resolved” and a patch has been applied to Cassandra 3.9 which has not been released yet. I believe I installed all the necessary packages such as java 8 and python 2.7.12. In the interim (until 3.9 is released) … Read more
How about the following, using Cassandra’s Lightweight transactions 1 – Create IDs table: CREATE TABLE ids ( id_name varchar, next_id int, PRIMARY KEY (id_name) ) 2 – Insert every id you’d like to use a global sequence with For example: INSERT INTO ids (id_name, next_id) VALUES (‘person_id’, 1) 3 – Then, when inserting to a … Read more
You could use “child process” module of nodejs to execute any shell commands or scripts with in nodejs. Let me show you with an example, I am running a shell script(hi.sh) with in nodejs. hi.sh echo “Hi There!” node_program.js const { exec } = require(‘child_process’); var yourscript = exec(‘sh hi.sh’, (error, stdout, stderr) => { … Read more
There is a lot of confusion around this, I will try to make it as simple as possible. The primary key is a general concept to indicate one or more columns used to retrieve data from a Table. The primary key may be SIMPLE and even declared inline: create table stackoverflow_simple ( key text PRIMARY … Read more
You should read the following and learn a little bit about the advantages of a well designed innodb table and how best to use clustered indexes – only available with innodb ! http://dev.mysql.com/doc/refman/5.0/en/innodb-index-types.html http://www.xaprb.com/blog/2006/07/04/how-to-exploit-mysql-index-optimizations/ then design your system something along the lines of the following simplified example: Example schema (simplified) The important features are that … Read more