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Event Store Launch
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eventstore
September 17, 2012
Programming
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Event Store Launch
eventstore
September 17, 2012
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Transcript
The Event Store 17th September 2012 Release! Skills Matter, London
Agenda • Demo • How to interact with the Event
Store • Internal architecture, decisions made • Something else… • Summary • Questions
DEMO TIME!
There are only 24 bytes of mutable data in the
Event Store
There are only 24 BYTES of mutable data in the
Event Store
Transaction File All data goes into a constantly appending file.
Transaction File Last Disk Flush
Transaction File Last Disk Flush Last Indexed
Transaction File The file is built up of many smaller
chunks of files.
Transaction File Chunk 1 Chunk 0
Transaction File Chunk 1 (1MB) Chunk 3 (1MB) Chunk 2
(1MB)
Scavenge 7 6 5 4 3 2 1 0 Index
has (1,2,7) deleted Scavenge 6 5 4 3 0 6 à 4 5 à 3 4 à 2 3 à 1 0 à 0
Transaction File Chunk 1 (1MB) Chunk 3 (1MB) Chunk 2
(1MB) Chunk 1a (1MB-) (items removed)
Transaction File Chunk 3 (1MB) Chunk 2 (1MB) Chunk 1a
(1MB-) (items removed)
TF Scavenge TF Chunks are immutable once written.
TF Scavenge Allows indexes and data storage to be scavenged
separately.
Indexes There is only one index in the Event Store.
Indexes Entries in index are 20 bytes each. (so 1
billion items is 20GB!)
Memtable 1 (up to 1M)
Memtable 1 (up to 1M) Ptable 1 (1M) Last Disk
Write
Memtable 1 (up to 1M) PTable 1 (1M) Last Disk
Write
PTable 01 (1M)
PTable 02 (1M) PTable 01 (1M)
PTable 03 (1M) PTable 02 (1M) PTable 01 (1M)
Merge
PTable 11 (4M)
PTable 11 (4M) PTable 01 (1M)
PTable 11 (4M) PTable 01 (1M) PTable 02 (1M)
PTable 03 (1M) PTable 11 (4M) PTable 01 (1M) PTable
02 (1M)
Merge
PTable 11 (4M) PTable 12 (4M)
PTable 11 (4M) PTable 01 (1M) PTable 12 (4M)
PTable 11 (4M) PTable 01 (1M) PTable 02 (1M) PTable
12 (4M)
PTable 03 (1M) PTable 11 (4M) PTable 01 (1M) PTable
02 (1M) PTable 12 (4M)
Indexes Indexes are immutable!
Indexes Reads have no locks!
No toasting of drives!
Simple When you look at what you have done and
think “Wow, it’s really simple” you have probably done something right.
Benchmarks! All benchmarks should be taken lightly for any system.
Usually they are biased!
Benchmarks! • Have indexed over 1B items with log(n) performance
Benchmarks! • Have indexed over 1B items with log(n) performance
• Writes! 15,000+/sec over TCP
Benchmarks! • Have indexed over 1B items with log(n) performance
• Writes! 15,000+/sec over TCP • Reads! 50,000+/sec over TCP
Pure async is good.
You can do a lot on one thread.
Immutability is good.
WAT?
There is an entire query language!
Projections Handle( Handle( Handle(state, Created), Deactivated), Closed)
Projections State, Event à State
Projections from_all().when( AccountCreated: function(state,event) { state.Name = event.CustomerName; state.Balance =
0; }, TransactionOccurred: function(state,event) { state.Balance += event.value; } );
Projections fromAll() fromStream(x,y,z) foreach(account)
Projection Indexes Link Link Link Link
Projection Indexes from_all().when_any( function(state, event) { emit(‘/streams/’ + event.Type, link_to(event));
} );
DEMO TIME!
Questions?
THANKS!
Coming 31st October
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