CouchDBApache

Monday, November 2, 2009

how couchdb treats the disksappend only btree

Replication

JSON

Map Reduce

HTTPMonday, November 2, 2009

intro:offline appssimple developmenteasy to deploy

! !

Stuart Langridge - Canonical

Monday, November 2, 2009

15 million desktops by the end of the year.solve the data island problem

Monday, November 2, 2009

raindrop - next gen messaging platformname: your own personal piece of the cloud

Monday, November 2, 2009

Monday, November 2, 2009

Couchapps -- easiest way to deploy an Ajax application that needs to store data.-- capable of scaling up with CouchDB. (etags etc)

http://www.flickr.com/photos/mcpig/872293700/

“Ground Computing”@jhuggins

Monday, November 2, 2009

app runs near the user. lower latency, lower cost.

Monday, November 2, 2009

http://www.flickr.com/photos/shane-h/280084650

Offline by Default

Monday, November 2, 2009

reliabletelephone poles / like akamai but for dynamic database backed applications. - same application on the client and server or the cloud

http://jacobian.org/writing/of-the-web/

http://apod.nasa.gov/apod/ap050930.html

“Of the Web”

Monday, November 2, 2009

Let me tell you something: Django may be built for the Web, but CouchDB is built of the Web. I've never seen software that so completely embraces the philosophies behind HTTP. ... this is what the software of the future looks like. Jacob Kaplan-Moss -- October, 2007

perfect spot - discovered not invented

When you can move data via replication, it

changes the physics of the web

so data is useful independent of location.

LocklessStorage

Monday, November 2, 2009

html5 story js ruby transactions?

-- getting CouchDB right involves going all the way to core lockless storage engine.

performance, map reduce, and deployment

B-Tree

Monday, November 2, 2009

data structuresorted by keysminimize disk seeks

Monday, November 2, 2009

logical btree

Monday, November 2, 2009

indexes - efficientkey lookupsrange scans

Append

OnlyMonday, November 2, 2009

robust / reliablenever touch bytes that are on diskcan’t be inconsistent

Monday, November 2, 2009

append only - in actionupdate J to a new value (rewrite j’s leaf node)

Monday, November 2, 2009

rewrite the path along the tree to Jup the parent path until we write the root.

Monday, November 2, 2009

all pointers point backwards into the file

Monday, November 2, 2009

update cost?

only has O(log n) cost where n is the # of keys

Monday, November 2, 2009

another update - add 5.

rewrite path to Z node to add 5

Monday, November 2, 2009

time follows the blue arrow. top half is actually an accumulation of updates like the bottom.note: batch efficiency -- save block updates

Monday, November 2, 2009

2 day test runcouchdb over long haul4 writers, 16 readers, random access, small keyspace - lots of 409s etc.

Incremental

ReduceMonday, November 2, 2009

takes advantage of the write pattern we’ve seensetup main storage doc count example

Monday, November 2, 2009

rereduce = falsecount # of keys in the block

Monday, November 2, 2009

rereduce = truesum # of docs in child nodesflexible range querying

Monday, November 2, 2009

intermediate reductions stored during a view calculationupdating J doesn’t change any counts, adding the 5 key does

Monday, November 2, 2009

we are rewriting the parent nodes anyway, so it makes sense to run the reduce calculation

Concurrent Access

Monday, November 2, 2009

readers see a consistent viewwe can support many readersreads don’t block writeswrites don’t block reads

Monday, November 2, 2009

concurrent readerslist all docs, then a write comes in, you don’t want to be surprised by an extra docreaders can be as long lived as they want without blocking writers or seeing inconsistencies

Local Web Platform

Monday, November 2, 2009

user interviews

http://www.longnow.org/projects/clock/orrery/Monday, November 2, 2009

append-onlyno fixup phasereliable and concurrentsequential write pattern (few writer seeks)hot backupscompaction