1.
data modeling for apache
cassandra
with a sprinkle of C* background and some time series fun
dani traphagen
@dtrapezoid

2.
quiz time - who is this?

3.
but
how
do I
even
?

4.
query driven methodology
conceptual data
model
access patterns
mapping
rules and
patterns
logical data
model
erd queries
diagram it

5.
conceptual data modeling
• abstract view of the domain
• technology independent
• not specific to any database system

6.
entity relationship diagram
• entity types
• relationship types
• attribute types

7.
relationship keys

8.
attribute key participation
• relationship attributes can make part
of the key

9.
full conceptual model

10.
query driven methodology
conceptual data
model
access patterns
mapping
rules and
patterns
logical data
model
erd queries
diagram it

11.
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

12.
application workflow

13.
query driven methodology
conceptual data
model
access patterns
mapping
rules and
patterns
logical data
model
erd queries
diagram it

14.
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

15.
mapping rules
1. entities and
relationships
2. equality search
attributes
3. inequality search
attributes
4. ordering attributes
5. key attributes

16.
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

17.
entities and relationships

18.
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
• 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

19.
equality search attributes
• equality search attributes become
initial columns of a primary key
• querying on: title and type

20.
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

21.
ordering attributes
1. ordering attributes become clustering columns
2. querying on: user_id = ? and
uploaded_timestamp > ?
3. ordering attributes : uploaded_timestamp (DESC)

22.
key attributes
1. relationship type key attributes are included as
primary key columns
2. queries affect primary key design

23.
query driven methodology
conceptual data
model
access patterns
mapping
rules and
patterns
logical data
model
erd queries
diagram it

24.
logical data model

25.
this
sucks
a real world example, w/time series data

26.
This is using simple strategy, but don’t do that in prod PLEASE!

27.
time series bucketing

28.
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

29.
& prepare to be wowed

30.
cdm
https://github.com/riptano/cdm
cdm preview

31.
namaste
but what does
it all mean?
also, we’re
hiring