data modeling for apache cassandra

with a sprinkle of C* background and some time series fun

dani traphagen@dtrapezoid

quiz time - who is this?

but how do I even

?

query driven methodologyconceptual data

model access patterns

mapping rules and patterns

logical data model

erd queries

diagram it

conceptual data modeling

• abstract view of the domain• technology independent• not specific to any database system

entity relationship diagram

• entity types• relationship types• attribute types

relationship keys

attribute key participation

• relationship attributes can make part of the key

full conceptual model

query driven methodologyconceptual data

model access patterns

mapping rules and patterns

logical data model

erd queries

diagram it

application workflow

• each application has a workflow• access patterns help us get how data

is accessed• know your queries you will run before

you design your model

application workflow

query driven methodologyconceptual data

model access patterns

mapping rules and patterns

logical data model

erd queries

diagram it

mapping rules & patterns

•mapping rules ensure that a logical data model is right• each query has a corresponding table• tables are designed to allow queries to

execute properly• tables return data in the correct order

mapping rules

1. entities and relationships

2. equality search attributes

3. inequality search attributes

4. ordering attributes 5. key attributes

entities and relationships

1. entity and relationship types map to tables

2. entities and relationships map to partitions or rows

3. partition may have data about one or more entities and relationships

4. attributes are represented by columns

entities and relationships

EachrelationshipbecomesarowinthetableRelationshiptypeattributesarerepresentedbycolumnsQueriesandrelationshipcardinalityaffectsthedesignoftheprimarykey

• each relationship becomes a row in the table• relationship type attributes are represented by columns• queries and relationship cardinality affects the design

of the primary key

equality search attributes

• equality search attributes become initial columns of a primary key

• querying on: title and type

inequality search attributes

• clustering columns follow partition key columns in a primary key

• the column involved in an inequality search must come after columns in the primary key that are used in an equality search

ordering attributes

1. ordering attributes become clustering columns2. querying on: user_id = ? and

uploaded_timestamp > ?3. ordering attributes : uploaded_timestamp (DESC)

key attributes

1. relationship type key attributes are included as primary key columns

2. queries affect primary key design

query driven methodologyconceptual data

model access patterns

mapping rules and patterns

logical data model

erd queries

diagram it

logical data model

this sucks

a real world example, w/time series data

Thisisusingsimplestrategy,butdon’tdothatinprodPLEASE!

time series bucketing

well dani this is all great and everything…but just how do i get

started? hm? i mean i want to learn cassandra and try it and everything

but it is just so daunting. i mean you showed me all this stuff and i am overwhelmed and it is sort of

making me insecure. what exactly do i do next to learn more? how do i

really dig in and learn these concepts? have you thought about

that? have you thought about what i NEED?

HMMMM DANI, HAVE YOU??!!!!!!!!!!11

& prepare to be wowed

cdmhttps://github.com/riptano/cdm

cdm preview

namaste

but what does it all mean?also, we’re

hiring