Author Archives: tobias

Apache Cassandra Secondary Indices

Posted on August 16, 2020 by tobias

How are Secondary Indices really stored ? This is based on the article from Datastax found here; https://www.datastax.com/blog/2016/04/cassandra-native-secondary-index-deep-dive Let’s just create a simple table

CREATE TABLE customer (
    id int PRIMARY KEY,
    city text,
    name text
)

CREATE TABLE customer (

id int PRIMARY KEY,

city text,

name text

)

Or visualized as a table : Column Type Key id int Primary Key city text name … Continue reading →

Posted in Cassandra | 3 Comments

Print stacktraces for all threads on shutdown

Posted on April 22, 2020 by tobias

If your microservice stops responding from time to time, and they only way out is to kill it with SIGINT or SIGTERM then adding a shutdown hook might be the way to go. Do note that this will not work … Continue reading →

Posted in debugging, JAVA, JVM, Scala | 2 Comments

Apache Zeppelin, with Spark and Cassandra, the perfect tool

Posted on April 5, 2020 by tobias

Zeppelin has become one of my favourite tools in my toolbox. I am heavily designing stuff for Cassandra and in Scala, and even though I love Cassandra there are times when things just gets so complicated with the CQL command … Continue reading →

Posted in Uncategorized | 7 Comments

Remove the cardo-updater agent from OSX

Posted on June 5, 2018 by tobias

I have the intercom from Cardo Systems, and it is really good BUT when I updated the firmware some time agoe, it decided to install some software that takes port 8080, which is one of those really common ports used … Continue reading →

Posted in Mac, OSX, tool | 13 Comments

SQL LIKE operation in Cassandra, is possible in v3.4+

Posted on August 12, 2016 by tobias

For a long time it has not been possible to do a SELECT * FROM table WHERE firstname like ‘t%’; in Cassandra like you could in eg.. MySQL or any other Relation Database for that matter. In Cassandra v3.4 this … Continue reading →

Posted in Uncategorized | 3 Comments

UDF/User Defined Functions in Cassandra 3.x

Posted on August 11, 2016 by tobias

I was just playing around with Cassandra WRITETIME and thought it was somewhat difficult to figure out the date / timestamp of a number like this (microseconds since EPOC) 1470645914253000. So in my example it looked like this

cqlsh:bth> select id, writetime(dateofbirth) from bth.employee;

 id | writetime(dateofbirth)
----+------------------------
  1 |       1470645914253000
  2 |       1470645977177000
  7 |       1470948508799001
  3 |       1470645977178000

(4 rows)
cqlsh:bth>

cqlsh:bth> select id, writetime(dateofbirth) from bth.employee;

id | writetime(dateofbirth)

----+------------------------

1 | 1470645914253000

2 | 1470645977177000

7 | 1470948508799001

3 | 1470645977178000

(4 rows)

cqlsh:bth>

So … Continue reading →

Posted in Cassandra, JAVA | 1 Comment

Cassandra set the writetime explicitly with a PreparedStatement

Posted on March 16, 2016 by tobias

This is a quick one, I wanted to set the writetime of a row explicitly when I populate the database for testing purposes. We use the writetime of a column to filter them out. It required some looking around to … Continue reading →

Posted in Cassandra, JAVA, Scala | 1 Comment

Apache SPARK and Cassandra and SQL

Posted on January 21, 2016 by tobias

This is a short intro to start using Apache SPARK with Cassandra, running SQL on the Cassandra tables. Note that I am not running a SPARK cluster, I am running “local”, to me this is really convenient, not having to … Continue reading →

Posted in Uncategorized | Tagged apache, cassandra, cassandrasqlcontext, dependencies, exception, nosuchmethodexception, sbt, scala, spark, sql | 2 Comments

SBT Good to know…

Posted on November 5, 2015 by tobias

Dependecy problems I have been having some difficulties figuring out what depends on what. I found the following set plugins which I think can be really helpful; https://github.com/jrudolph/sbt-dependency-graph and https://github.com/gilt/sbt-dependency-graph-sugar Be sure to install GraphWiz first, I used Homebrew on … Continue reading →

Posted in SBT, Scala | 1 Comment

Create an MBean (JMX) in Scala

Posted on November 3, 2015 by tobias

Create the MBean like this

trait OrderTrackerMBean {
  def getOrderId : Int
  def setOrderId(orderId:Int)
}

class OrderTracker extends OrderTrackerMBean {
  var orderId = 0
  override def getOrderId: Int = orderId
  override def setOrderId(_orderId: Int)= {
    orderId = _orderId
  }

}

trait OrderTrackerMBean {

def getOrderId : Int

def setOrderId(orderId:Int)

}

class OrderTracker extends OrderTrackerMBean {

var orderId = 0

override def getOrderId: Int = orderId

override def setOrderId(_orderId: Int)= {

orderId = _orderId

}

NOTE, that the interface/trait must end with MBean in the name And this is how you register your MBean

package com.tsoft.playingWithLogback

import java.lang.management.ManagementFactory
import javax.management.{ObjectName, MBeanServer}

import org.slf4j.{MarkerFactory, Marker, LoggerFactory}
import org.slf4j.MDC
import scala.concurrent.{Await, Future}
import scala.concurrent.duration._
import scala.concurrent.ExecutionContext.Implicits.global

object LotsOfLogOutput {

  val logger = LoggerFactory.getLogger(this.getClass)

  val orderTrackerBean = new OrderTracker
  val mbs:MBeanServer = ManagementFactory.getPlatformMBeanServer();
  val mBeanName:ObjectName = new ObjectName("com.tsoft.playingWithLogback:type=Tracking");
  mbs.registerMBean( orderTrackerBean, mBeanName);

...

package com.tsoft.playingWithLogback

import java.lang.management.ManagementFactory

import javax.management.{ObjectName, MBeanServer}

import org.slf4j.{MarkerFactory, Marker, LoggerFactory}

import org.slf4j.MDC

import scala.concurrent.{Await, Future}

import scala.concurrent.duration._

import scala.concurrent.ExecutionContext.Implicits.global

object LotsOfLogOutput {

val logger = LoggerFactory.getLogger(this.getClass)

val orderTrackerBean = new OrderTracker

val mbs:MBeanServer = ManagementFactory.getPlatformMBeanServer();

val mBeanName:ObjectName = new ObjectName("com.tsoft.playingWithLogback:type=Tracking");

mbs.registerMBean( orderTrackerBean, mBeanName);

...

And the simply launch Java Mission Control (imc), attach to the JVM, and modify … Continue reading →

Posted in Uncategorized | 2 Comments

Author Archives: tobias

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