1. annalist,
an Erlang stats aggregator
Florian Odronitz @ Berlin Erlounge July 2012

2. Motivation
• Application Statistics in Erlang
• Count things (e.g. new users/day)
• Record stats (e.g. 95 percentile of response
time)
• Pretty graphs
• CSV for the Excel-folks

3. Concept
• Store stuff in two granularities
• Time and hierarchical tags
• so count([<<“read”>>, <<“book”>>])
increments the counter in 14 keys

4. read/total
read/year/2012
read/month/2012/07
read/day/2012/07/24
read/hour/2012/07/24/23
read/minute/2012/07/24/23/01
read/second/2012/07/24/23/01/22
read/total
read/book/year/2012
read/book/month/2012/07
read/book/day/2012/07/24
read/book/hour/2012/07/24/23
read/book/minute/2012/07/24/23/01
read/book/second/2012/07/24/23/01/22

5. Components
• LevelDB stores data
• eleveldb interfaces with LevelDB
• uplevel provides bucket/key semantics and
range queries
• Cowboy for JSON API
• sparks.js and Highstocks for graphs

6. LevelDB
• Local, persistent key-value store
• Ordered by key, iterations
• Atomic writes and snapshots
• Variable Cache Size

7. Features: Counting
annalist:count([<<"create">>, <<"opinion">>])

8. Features: Counting

9. Features: Counting

10. Features: Recording
annalist:record([<<"time">>, <<"get_user">>], 62.3)

11. Features: Recording

12. Features: Recording
• Store distributions of values in a space efficient
manner with accuracy guaranties.
• Targeted Quantiles:
f_targeted([{0.05, 0.005}, {0.5, 0.02}, {0.95, 0.005}])
Allow a maximum error of 0,5% for 5th and 95th
percentile and 2% error for median. Errors are
errors in rank.

13. Features: Recording

14. Features: Recording
1x107
1x106
100000
10000
Value
1000
100
10
1
0 2000 4000 6000 8000 10000 12000 14000
Inserts

15. Features: Recording
1x107
1x106
100000
10000
Value
1000
100
10
1
0 2000 4000 6000 8000 10000 12000 14000
Inserts

16. Features: Recording
80
Compressed size (comp. every 10 inserts)
60
40
20
0
0 2000 4000 6000 8000 10000 12000 14000
Inserts

17. Features: API
/annalist/hour_counts/
update%20user_location/
2011/7/30/21/8640
?callback=jQuery123
jQuery123([0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0...0,0,0,19,81,73,96,139,205,120,79,25,0,0,0,0,0,0
,0,0,0,0,52,86,76,0,25,89,93,97,80,56,38,0,13,37,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,38,80,80,117,80,80,80
,80,80,79,80,80,12,0,0,0,0,0,0,0,0,0,0,0,0,72,80,80,79,79,80,80,80,80,80,80,80,80,80,196,208,240,249,236,160,160
,138,196,160,159,162,93,80,78,81,79,80,80,80,81,49,81,81,62,3,41,84,82,100,134,80,79,14,80,80,80,80,80,80,80,80,
79,80,80,67,60,68,158,79,77,211,242,231,209,80,105,161,206,240,240,238,240,237,239,239,239,239,241,148,80,80,80,
80,80,80,80,80,134,108,80,90,205,222,85,79,80,80,79,81,77,80,81,79,82,84,79,175,293,239,116,80,78,79,186,232,126
,142,22,163,177,175,176,164,168,167,166,180,177,173,168,34,0,0,109,179,180,176,178,162,180,174,173,163,175,166,1
73,173,178,179,164,130,0,0,0,0,21,11,0,0,0,17,44,141,145,162,73,0,0,0,0,5,118,0,6,0,197,232,0,69,80,80,80,78,28,
24,0,49,80,72,75,70,2,0,0,0,0,0,0,0,24,166,373,290,309,260,275,232,123,138,132,80,79,95,79,125,132,80,79,80,79,8
1,80,79,113,99,101,92,139,204,244,250,224,194,166,80,223,188,80,80,78,73,80,79,35,0,0,9,148,169,301,300,304,263,
109,251,272,171,138,114,183,184,12,0,0,0,0,0,0,0,0,0,189,299,145,114,184,174,196,225,241,264,231,52,85,163,166,5
0,3,11,15,9,29,55,19,84,149,132,115,90,68,56,97,112,235,315,301,289,274,223,242,273,260,260,293,308,294,189,180,
187,242,198,178,225,248,248,244,433,359,227,180,223,206,180,179,180,180,180,179,181,179,184,241,131,227,322,310,
286,260,271,327,348,319,187,161,108,79,80,0,0,0,0,0,0,0,44,166,149,148,13,0,41,81,25,0,166,49,4,113,107,0]);

18. Characteristic

19. Characteristic
• Sparse counting
• No backpressure
• 1 gen_server, 1 CPU
• eventually consistent

20. Performance
• Counting:
~ 4k ops/sec with ([<<“a”>>, <<“b”>>])
equals ~ 56k increments/sec
• Stats:
~ 690 ops/sec with ([<<“a”>>, <<“b”>>], 1)
equals ~ 9.66k recordings/sec

21. Future
• HTTP API for stats
• CSV Export
• Purging
• Variable Timeslots
• Multiple Workers (CAS with locks in ets?)

22. Thanks
• leveldb.googlecode.com
• https://github.com/basho/eleveldb
• https://github.com/odo/uplevel
• https://github.com/odo/annalist
• https://github.com/extend/cowboy/
• http://omnipotent.net/jquery.sparkline/
• highcharts.com