#CASSANDRA13

Ma#hew  Stump  |  Architect  @  KISSmetrics

Real-time Large Queries

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KISSmetrics Customers Want*Churn Prediction

*AB Tests

*Which Blog Posts and Ad Campaigns Attract High Value Customers?

*User Conversion Funnel

*Revenue Prediction

*Customer Acquisition Costs

*Customer Lifetime Value

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Understanding Queries

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RowKey username first_name last_name postal_code

cstar cstar Cassandra Database 94110

user2 user2 Some Guy 94112

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RowKey username first_name last_name postal_code

cstar cstar Cassandra Database 94110

user2 user2 Some Guy 94112

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RowKey username first_name last_name postal_code

cstar cstar Cassandra Database 94110

user2 user2 Some Guy 94112

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RowKey

94110 cstar

94112 user2 user4 user7 ...

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Where Secondary Indexes Break

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*High Cardinality Data

*Only one index per query

*Indexes are distributed

*Only some datatypes; no counters

*Range queries are expensive

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What Do I Want?

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*Index high cardinality data; e.g. counters

*Complex queries, with multiple clauses

*Results in < 500ms for billions of rows

*Sub-field searching with regular expressions

*Range queries

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Bitmap and Bit-Slice Indexes

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RowKey

94110 cstar

94112 user2 user4 user7 ...

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RowKey

94110 00001000 01000000 00000000 000000000

94112 10000110 01000000 00000000 000000000

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RowKey

94110 00001000 01000000 00000000 000000000

94112 10000110 01000000 00000000 000000000

hash(“cstar”) = 4

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SELECT * FROM users WHERE zipcode = 94110 OR zipcode = 94112

94112 or 94110

10001110 01000000 00000000 000000000

Field Index

94110 10001010 01000000 00000000 000000000

94112 10000110 01000000 00000000 000000000

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SELECT * FROM users WHERE Event1 = true AND Event2 = true

Event1 and Event2

10000010 01000000 00000000 000000000

Field Index

Event1 10001010 01000000 00000000 000000000

Event2 10000110 01000000 00000000 000000000

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Field Value Slice

event_counter 1 10001010 01000000 00000000 000000000

event_counter 2 10000110 01000000 00000000 000000000

SELECT * FROM users WHERE event_counter < 5

Value1 or Value2

10000010 01000000 00000000 000000000

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"this is a test string"

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['thi', 's i', 's a', ' te', 'st ', 'str', 'ing']

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['0x746869', '0x732069', '0x732061', '0x207465', '0x737420', '0x737472', '0x696e67']

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Field Value Slice

text_field 0x207465 ' te' 10001010 01000000 00000000 000000000

text_field 0x696e67 'ing' 10111110 10001000 00000000 000001000

text_field 0x732061 's a' 10001010 01000001 00001000 110101110

text_field 0x732069 's i' 10001010 01000000 10110011 000000000

text_field 0x737420 'st ' 10001010 01001100 10110111 000000000

text_field 0x737472 'str' 10001010 01000000 00011010 011000000

text_field 0x746869 'thi' 10001010 01000000 10110111 000000010

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"thi.*ing"

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"thi" AND "ing"

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0x746869 AND 0x696e67

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Field Value Slice

text_field 0x207465 ' te' 10001010 01000000 00000000 000000000

text_field 0x696e67 'ing' 10111110 10001000 00000000 000001000

text_field 0x732061 's a' 10001010 01000001 00001000 110101110

text_field 0x732069 's i' 10001010 01000000 10110011 000000000

text_field 0x737420 'st ' 10001010 01001100 10110111 000000000

text_field 0x737472 'str' 10001010 01000000 00011010 011000000

text_field 0x746869 'thi' 10001010 01000000 10110111 000000010

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"th.*ing"

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"th" AND "ing"

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range(0x746800, 0x7468FF) AND 0x696e67

range("th" + 0x00, "th" + 0xFF) AND "ing"

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Field Value Slice

text_field 0x207465 ' te' 10001010 01000000 00000000 000000000

text_field 0x696e67 'ing' 10111110 10001000 00000000 000001000

text_field 0x732061 's a' 10001010 01000001 00001000 110101110

text_field 0x732069 's i' 10001010 01000000 10110011 000000000

text_field 0x737420 'st ' 10001010 01001100 10110111 000000000

text_field 0x737472 'str' 10001010 01000000 00011010 011000000

text_field 0x746869 'thi' 10001010 01000000 10110111 000000010

text_field 0x74687A 'thz' 10000000 00000001 00011100 000110010

range(0x746800, 0x7468FF) AND 0x696e67

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Implementation

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Query & Indexing Engine

Queries and Events

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RowKey Offset 0x00 Offset 0x01 Offset 0x02 Offset 0x03

event1_0x00 10011000 10011000

event1_0x01 10011000 10011000 10011000

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Results So Far*Results returned for an 8 clause query for 4 billion rows < 2 second

*Full regular expression support

*Full support for range queries

*Ability to index any numeric value, or value which can be hashed.

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What isn't finished*Support for atomic counters

*"Group By" query aggregation

*Still working on event processing and distribution

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https://github.com/project-z/

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mstump@kissmetrics.com@mattstump

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THANK YOU