2. #MDBlocal
Agenda
● Discuss the MongoDB document model
● Discuss how data can be migrated to MongoDB
● Discuss important MongoDB schema design considerations
● Talk through common approaches to MongoDB schema migration
● Outline how threading and batching can be leveraged for ETL purposes
3. #MDBlocal
Introduction
● At some point, most applications need to batch-load large amounts of data
○ Billions of rows
○ Huge initial load
○ Daily updates (CDC)
● This is typically facilitated using an ETL platform
11. #MDBlocal
Example > Guitar Collectors
Typical queries from a consumer of this data might be:
● “What guitars does Aimee Doe own?”
● “Show me all the people who own a Gibson
Les Paul of any age”
● “How many people within 100 miles of Seattle
own guitars made before 1970?”
Consider how the data will be used
X
12. #MDBlocal
Example > Guitar Collectors
Consider how the data will be used
Typical queries from a consumer of this data might be:
● “What guitars does Aimee Doe own?”
● “Show me all the people who own a Gibson
Les Paul of any age”
● “How many people within 100 miles of Seattle
own guitars made before 1970?”
25. #MDBlocal
ORDER
S
TRACKING
ITEM
S
ID FIRST_NAME LAST_NAME SHIPPING_ADDRESS
1 James Bond Nassau, Bahamas, US
2 Ernst Blofeldt Caracas, Venezuela
ID ORDER_ID QTY DESCRIPTION PRICE
1 1 1 Aston Martin 120,000
2 1 1 Dinner Jacket 4,000
3 1 3 Champagne Veuve-Cliquot 200
4 2 100 Cat Food 1
5 2 1 Launch Pad 1,000,000
ORDER_ID TIMESTAMP STATUS
1 1985-04-30 09:48:00 ORDERED
2 1985-04-23 01:30:22 ORDERED
2 1985-04-25 08:30:00 SHIPPED
2 1985-05-14 21:37:00 DELIVERED
26. #MDBlocal
Approach #1 – Nested Queries
for x in SELECT * FROM ORDERS
doc = { "first_name" : x.first_name,
"last_name" : x.last_name,
"address" : x.address,
"items" : [], "tracking" : [] }
for y in SELECT * FROM ITEMS WHERE ORDER_ID = x.order_id
doc.items.push (y)
for z in SELECT * FROM TRACKING WHERE ORDER_ID = x.order_id
doc.tracking.push (y)
mongodb.insert (doc)
27. #MDBlocal
Approach #1 – Nested Queries
for x in SELECT * FROM ORDERS
doc = { "first_name" : x.first_name,
"last_name" : x.last_name,
"address" : x.address,
"items" : [], "tracking" : [] }
for y in SELECT * FROM ITEMS WHERE ORDER_ID = x.order_id
doc.items.push (y)
for z in SELECT * FROM TRACKING WHERE ORDER_ID = x.order_id
doc.tracking.push (y)
mongodb.insert (doc)
28. #MDBlocal
Approach #1 – Nested Queries
for x in SELECT * FROM ORDERS
doc = { "first_name" : x.first_name,
"last_name" : x.last_name,
"address" : x.address,
"items" : [], "tracking" : [] }
for y in SELECT * FROM ITEMS WHERE ORDER_ID = x.order_id
doc.items.push (y)
for z in SELECT * FROM TRACKING WHERE ORDER_ID = x.order_id
doc.tracking.push (y)
mongodb.insert (doc)
29. #MDBlocal
Approach #1 – Nested Queries
for x in SELECT * FROM ORDERS
doc = { "first_name" : x.first_name,
"last_name" : x.last_name,
"address" : x.address,
"items" : [], "tracking" : [] }
for y in SELECT * FROM ITEMS WHERE ORDER_ID = x.order_id
doc.items.push (y)
for z in SELECT * FROM TRACKING WHERE ORDER_ID = x.order_id
doc.tracking.push (y)
mongodb.insert (doc)
30. #MDBlocal
Approach #1 – Nested Queries
for x in SELECT * FROM ORDERS
doc = { "first_name" : x.first_name,
"last_name" : x.last_name,
"address" : x.address,
"items" : [], "tracking" : [] }
for y in SELECT * FROM ITEMS WHERE ORDER_ID = x.order_id
doc.items.push (y)
for z in SELECT * FROM TRACKING WHERE ORDER_ID = x.order_id
doc.tracking.push (y)
mongodb.insert (doc)
31. #MDBlocal
Approach #1 – Nested Queries
for x in SELECT * FROM ORDERS
doc = { "first_name" : x.first_name,
"last_name" : x.last_name,
"address" : x.address,
"items" : [], "tracking" : [] }
for y in SELECT * FROM ITEMS WHERE ORDER_ID = x.order_id
doc.items.push (y)
for z in SELECT * FROM TRACKING WHERE ORDER_ID = x.order_id
doc.tracking.push (y)
mongodb.insert (doc)
34. #MDBlocal
Approach #2 – Build Documents In DB
for x in SELECT * FROM ORDERS
doc = { "first_name" : x.first_name,
"last_name" : x.last_name,
"address" : x.address,
"items" : [], "tracking" : [] }
mongodb.insert (doc)
for y in SELECT * FROM ITEMS
mongodb.update ({"_id" : y.order_id},
{"$push" : {"items" : y}})
for z in SELECT * FROM TRACKING
mongodb.update ({"_id" : z.order_id},
{"$push" : {"tracking" : z}})
35. #MDBlocal
Approach #2 – Build Documents In DB
for x in SELECT * FROM ORDERS
doc = { "first_name" : x.first_name,
"last_name" : x.last_name,
"address" : x.address,
"items" : [], "tracking" : [] }
mongodb.insert (doc)
for y in SELECT * FROM ITEMS
mongodb.update ({"_id" : y.order_id},
{"$push" : {"items" : y}})
for z in SELECT * FROM TRACKING
mongodb.update ({"_id" : z.order_id},
{"$push" : {"tracking" : z}})
36. #MDBlocal
Approach #2 – Build Documents In DB
for x in SELECT * FROM ORDERS
doc = { "first_name" : x.first_name,
"last_name" : x.last_name,
"address" : x.address,
"items" : [], "tracking" : [] }
mongodb.insert (doc)
for y in SELECT * FROM ITEMS
mongodb.update ({"_id" : y.order_id},
{"$push" : {"items" : y}})
for z in SELECT * FROM TRACKING
mongodb.update ({"_id" : z.order_id},
{"$push" : {"tracking" : z}})
37. #MDBlocal
Approach #2 – Build Documents In DB
for x in SELECT * FROM ORDERS
doc = { "first_name" : x.first_name,
"last_name" : x.last_name,
"address" : x.address,
"items" : [], "tracking" : [] }
mongodb.insert (doc)
for y in SELECT * FROM ITEMS
mongodb.update ({"_id" : y.order_id},
{"$push" : {"items" : y}})
for z in SELECT * FROM TRACKING
mongodb.update ({"_id" : z.order_id},
{"$push" : {"tracking" : z}})
38. #MDBlocal
Approach #2 – Build Documents In DB
for x in SELECT * FROM ORDERS
doc = { "first_name" : x.first_name,
"last_name" : x.last_name,
"address" : x.address,
"items" : [], "tracking" : [] }
mongodb.insert (doc)
for y in SELECT * FROM ITEMS
mongodb.update ({"_id" : y.order_id},
{"$push" : {"items" : y}})
for z in SELECT * FROM TRACKING
mongodb.update ({"_id" : z.order_id},
{"$push" : {"tracking" : z}})
39. #MDBlocal
Approach #2 – Build Documents In DB
for x in SELECT * FROM ORDERS
doc = { "first_name" : x.first_name,
"last_name" : x.last_name,
"address" : x.address,
"items" : [], "tracking" : [] }
mongodb.insert (doc)
for y in SELECT * FROM ITEMS
mongodb.update ({"_id" : y.order_id},
{"$push" : {"items" : y}})
for z in SELECT * FROM TRACKING
mongodb.update ({"_id" : z.order_id},
{"$push" : {"tracking" : z}})
40. #MDBlocal
Fan-In & Fan-Out
Number of Database Operations per MongoDB Document
ETL Job3 per order 1 + i + t
i = # of assoc. line items
t = # of assoc. tracking rows
73. #MDBlocal
Summary
● Remember the two big rules regarding MongoDB schema design
○ Consider how the data will be used
○ Data that works together lives together
● Consider the common approaches to MongoDB schema migration
● Prototype, prototype, prototype
● Don’t forget to utilise batching and threading