CASSANDRA DAY ATLANTA 2015

SOFTWARE DEVELOPMENT WITH CASSANDRA:A WALKTHROUGH

Nate McCall@zznate

#CassandraDaysCo-Founder & Sr. Technical Consultant

Licensed under a Creative Commons Attribution-NonCommercial 3.0 New Zealand License

About The Last Pickle.

Work with clients to deliver and improve Apache Cassandra based solutions.

Based in New Zealand & USA.

OVERVIEW

Overview:

What makes a software development

project successful?

Overview: Successful Software Development

- it ships- maintainable- good test coverage- check out and build

Overview:

Impedance mismatch:distributed systems

developmenton a laptop.

DATA MODELING

Data Modeling:

a topic unto itself.But quickly:

Data Modeling - Quickly

Its Hard Do research #1 performance problem Tip: dont port your schema

Data Modeling - Using CQL:

tools support easy tracing (and trace discovery) documentation*

*Maintained in-tree:https://github.com/apache/cassandra/blob/cassandra-1.2/doc/cql3/CQL.textilehttps://github.com/apache/cassandra/blob/cassandra-2.0/doc/cql3/CQL.textilehttps://github.com/apache/cassandra/blob/cassandra-2.1/doc/cql3/CQL.textile

Data Modeling - DevCenter :

Tools:DataStax DevCenter

http://www.datastax.com/what-we-offer/products-services/devcenter

WRITING CODE

Writing Code:

ORM?maybe - only if its very simple

more later

http://www.datastax.com/documentation/developer/java-driver/2.1/java-driver/reference/crudOperations.html

Writing Code:

use CQL

Writing Code:

Use the Java Driver

Writing Code - Java Driver :

Reference implementation Well written, extensive coverage open source dedicated resourceshttps://github.com/datastax/java-driver/

Writing Code - Java Driver :

Existing Spring Users:Spring Data Integration

http://projects.spring.io/spring-data-cassandra/

Writing Code - Java Driver :

Guice Users:GuicyFig:

Archaius + Guice

https://stash.safehaus.org/projects/GFIG/repos/main/browse

Writing Code - Java Driver :

Four rules for Writing Code one Cluster for physical cluster one Session per app per keyspace use PreparedStatements use Batches to reduce network IO

Writing Code - Java Driver :

Configuration is Similar to Other DB Drivers(with caveats**)

http://www.datastax.com/documentation/developer/java-driver/2.1/common/drivers/reference/clusterConfiguration_c.html

Writing Cluster - Java Driver - Configuration:

Major Difference:its a Cluster!

Writing Code - Java Driver - Configuration:

Two groups of configurations

policies connections

Writing Code - Java Driver - Configuration:

Three Policy Types: load balancing connection retry

Writing Code - Java Driver - Configuration:

Connection Options: protocol* pooling socket

*https://github.com/apache/cassandra/blob/cassandra-2.1/doc/native_protocol_v3.spec

Writing Code - Java Driver :

Embrace Asynchronicity(but use RxJava)

https://github.com/ReactiveX/RxJava

Writing Code - Java Driver :

A note about User Defined Types (UTDs)

Writing Code - Java Driver - Using UDTs:

Wait.- serialized as blobs !!?!- new version already being discussed*- will be a painful migration path

* https://issues.apache.org/jira/browse/CASSANDRA-7423

Writing Code:

Metrics API for your own code

https://github.com/apache/cassandra/blob/cassandra-2.1/src/java/org/apache/cassandra/metrics/ColumnFamilyMetrics.javahttps://dropwizard.github.io/metrics/3.1.0/

Writing Code - Instrumentation via Metrics API:

Run Riemann locally

http://riemann.io/

Writing Code:

Using Trace (and doing so frequently)

Writing Code - Tracing:

Trace per query via DevCenter

http://www.datastax.com/documentation/cql/3.0/cql/cql_reference/tracing_r.html

Writing Code - Tracing:

Trace per query via cqlsh

http://www.datastax.com/documentation/cql/3.0/cql/cql_reference/tracing_r.html

cqlsh> tracing on;Now tracing requests.cqlsh> SELECT doc_version FROM data.documents_by_version ... WHERE application_id = myapp ... AND document_id = foo ... AND chunk_index = 0 ... ORDER BY doc_version ASC ... LIMIT 1;

doc_version------------- 65856

Tracing session: 46211ab0-2702-11e4-9bcf-8d157d448e6b

Preparing statement | 18:05:44,845 | 192.168.1.197 | 22337 Enqueuing data request to /192.168.1.204 | 18:05:44,845 | 192.168.1.197 | 22504 Sending message to /192.168.1.204 | 18:05:44,847 | 192.168.1.197 | 24498 Message received from /192.168.1.197 | 18:05:44,854 | 192.168.1.204 | 872 Executing single-partition query on documents_by_version | 18:05:44,888 | 192.168.1.204 | 35183 Acquiring sstable references | 18:05:44,888 | 192.168.1.204 | 35459 Merging memtable tombstones | 18:05:44,889 | 192.168.1.204 | 35675 Key cache hit for sstable 2867 | 18:05:44,889 | 192.168.1.204 | 35792 Seeking to partition beginning in data file | 18:05:44,889 | 192.168.1.204 | 35817

Preparing statement | 18:05:44,845 | 192.168.1.197 | 22337 Enqueuing data request to /192.168.1.204 | 18:05:44,845 | 192.168.1.197 | 22504 Sending message to /192.168.1.204 | 18:05:44,847 | 192.168.1.197 | 24498 Message received from /192.168.1.197 | 18:05:44,854 | 192.168.1.204 | 872 Executing single-partition query on documents_by_version | 18:05:44,888 | 192.168.1.204 | 35183 Acquiring sstable references | 18:05:44,888 | 192.168.1.204 | 35459 Merging memtable tombstones | 18:05:44,889 | 192.168.1.204 | 35675 Key cache hit for sstable 2867 | 18:05:44,889 | 192.168.1.204 | 35792 Seeking to partition beginning in data file | 18:05:44,889 | 192.168.1.204 | 35817

Merging data from memtables and 8 sstables | 18:05:44,892 | 192.168.1.204 | 38605 Read 1 live and 2667 tombstoned cells | 18:05:54,135 | 192.168.1.204 | 9282428 Enqueuing response to /192.168.1.197 | 18:05:54,136 | 192.168.1.204 | 9283423 Sending message to /192.168.1.197 | 18:05:54,138 | 192.168.1.204 | 9284753 Message received from /192.168.1.204 | 18:05:54,155 | 192.168.1.197 | 9332505 Processing response from /192.168.1.204 | 18:05:54,158 | 192.168.1.197 | 9335372 Request complete | 18:05:54,158 | 192.168.1.197 | 9335592

Merging data from memtables and 8 sstables | 18:05:44,892 | 192.168.1.204 | 38605 Read 1 live and 2667 tombstoned cells | 18:05:54,135 | 192.168.1.204 | 9282428 Enqueuing response to /192.168.1.197 | 18:05:54,136 | 192.168.1.204 | 9283423 Sending message to /192.168.1.197 | 18:05:54,138 | 192.168.1.204 | 9284753 Message received from /192.168.1.204 | 18:05:54,155 | 192.168.1.197 | 9332505 Processing response from /192.168.1.204 | 18:05:54,158 | 192.168.1.197 | 9335372 Request complete | 18:05:54,158 | 192.168.1.197 | 9335592

!!?!

Merging data from memtables and 8 sstables | 18:05:44,892 | 192.168.1.204 | 38605 Read 1 live and 2667 tombstoned cells | 18:05:54,135 | 192.168.1.204 | 9282428 Enqueuing response to /192.168.1.197 | 18:05:54,136 | 192.168.1.204 | 9283423 Sending message to /192.168.1.197 | 18:05:54,138 | 192.168.1.204 | 9284753 Message received from /192.168.1.204 | 18:05:54,155 | 192.168.1.197 | 9332505 Processing response from /192.168.1.204 | 18:05:54,158 | 192.168.1.197 | 9335372 Request complete | 18:05:54,158 | 192.168.1.197 | 9335592

Writing Code - Tracing:

Enable traces in the driver

http://www.datastax.com/documentation/developer/java-driver/2.0/java-driver/tracing_t.html

Writing Code - Tracing:

`nodetool settraceprobability`

Writing Code - Tracing:

then make sure you try it again

with a node down!

Writing Code - Tracing:

Final note on tracing:do it sparingly

Writing Code - Tracing:

Coming Soon:slow query log

(client side)

https://github.com/datastax/java-driver/compare/java646https://datastax-oss.atlassian.net/browse/JAVA-646

Writing Code:

Logging Verbositycan be changed dynamically**

** since 0.4rc1

http://www.datastax.com/documentation/cassandra/2.0/cassandra/configuration/configLoggingLevels_r.html

Writing Code:

nodetool for developers cfstats cfshistograms proxyhistograms

Writing Code - nodetool - cfstats:

cfstats:per-table statistics about size

and performance (single most useful command)

Writing Code - nodetool - cfhistograms:

cfhistograms:column count and partition size vs. latency distribution

Writing Code - nodetool - proxyhistograms:

proxyhistograms:performance of inter-cluster

requests

MANAGING ENVIRONMENTS

Managing Environments:

Configuration Management is Essential

Managing Environments:

Laptop to Productionwith NO

Manual Modifications!

Managing Environments:

Running Cassandraduring development

Managing Environments - Running Cassandra:

Local Cassandra easy to setup you control it but then you c