crisis
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respond to page in the middle of the night
whatever alert sent page isn't enough to solve the problem, or
you would have automated it
if you can see at a glance it's faster than grepping through logs
=> reduce downtime
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anomalies
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notice things you haven't seen before
things you haven't planned for
prompt investigation into odd behavior
see the interactions between lots of things
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capacity
planning
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should I upgrade?
are there daily/weekly cycles?
=> increases robustness
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remove guessing
and gut feelings
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history
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"let's start with some history
"inspiration, lessons, and they're just really
neat
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playfiar
william
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w 1759-1823
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title, frame, labeled axes, labels in the graph, caption,
color
- in 1786 the line graph and bar chart
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- in 1801 the pie chart and circle graph
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John Snow
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- 1854 Broad Street cholera outbreak (soho
london)
- germ theory was not yet widely accepted
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jenny downing
http://www.flickr.com/photos/jenny-pics/3761648387/
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There was one significant anomaly - none of the monks in the
adjacent monastery contracted cholera. Investigation showed
that this was not an anomaly, but further evidence, for they
drank only beer, which they brewed themselves
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Charles
Joseph
Minard
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w 1781-187
0
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Napoleon graph of 1812 (made in 1869)
needs explanation, but has wonderful density
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Edward
Tufte
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data-ink ratio
data-ink ratio
data-ink ratio
data-ink ratio
data-ink ratio
data-ink ratio
data-ink ratio
data-ink ratio
data-ink ratio
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honesty
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important not to mislead, even unintentionally (time zone)
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information
consists of
differences
that make a
difference
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sparklines
http://tinyurl.com/sparkline
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small multiples
intense data
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charts
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get a little more practical
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line
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an aside
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wIJTUPHSBN
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horizon
WJTCFSLFMFZFEVQBQFSTIPSJ[PO
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http://square.github.io/cubism/
position—small
color—large
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compress vertically without loosing resolution
=> select * from pg_stat_statements limit 1;
userid | 16384
dbid | 16385
query | SELECT "clip_versions".* FROM "clip_versions"
WHERE "clip_versions"."clip_id" = ? ORDER BY created_at desc
calls | 103
total_time | 37.603
rows | 632
shared_blks_hit | 504
shared_blks_read | 210
shared_blks_dirtied | 0
shared_blks_written | 0
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select
((total_time::float/calls)::int
/ 50) * 50 as ms,
lpad('', count(*)::int, '')
|| ' '
|| count(*) as freq
from pg_stat_statements
group by 1 order by 1; \watch 1
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stat views
pg_stat_activity
pg_stat_database
pg_stat_user_tables
pg_stat_user_indexes
pg_statio_user_tables
pg_statio_user_indexes
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transactions, rollbacks, bloat, cache hit
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pg-extras
https://github.com/heroku/heroku-pg-extras
cache hit ratio
index usage
running queries
blocked queries
locks
index size
unused indexes
sequential scans
bloat
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designing a
system
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not easy
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there aren't concrete rules to human perception
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data is not
information
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just having a metric in graphite or libretto isn't enough
-- other people won't have the same context
-- you probably need to do conversions such as derivatives
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too much
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you get X position Y position and a few colors
aspect ratio should make lines 45º if possible
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Cant line up the same time period
Minimize Context switching
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color
http://tinyurl.com/colorrules
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Gray or muted background
soft, nature colors for most, bright sparingly
for similar categories: single hue, vary saturation
different categories: vary hue, but keep saturation
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intents and needs
NF
ECB
DPOUSBDUPS
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generation
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Peter Eisentraut => logging yesterday
storage
http://www.flickr.com/photos/lightmash/3183278318/
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storing time series data is a talk in and of
itself
=>Ronald’s talk yesterday
no way i can do it justice as part of this talk
rollup, table rotation