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Elasticsearch: updating the mappings and settings of an existing index

Note: This was written using elasticsearch 0.9.

Elasticsearch will automatically create an index (with basic settings and mappings) for you if you post a first document:

$ curl -X POST 'http://localhost:9200/thegame/weapons/1' -d \
'{
  "_id": 1,

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package future

// A Future represents the result of some asynchronous computation.
// Future returns the result of the work as an error, or nil if the work
// was performed successfully.
// Implementers must observe these invariants
// 1. There may be multiple concurrent callers, or Future may be called many
//     times in sequence, it must always return the same value.
// 2. Future blocks until the work has been performed.
type Future func() error

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Channels Are Not Enough

... or Why Pipelining Is Not That Easy

Golang Concurrency Patterns for brave and smart.

By @kachayev

Intro

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Twelve Go Best Practices

Francesc Campoy Flores Gopher at Google @francesc http://campoy.cat/+

http://golang.org

• Best practices

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Variance

The term variance describes how subtyping between higher kinded types is related to subtyping relations of their type arguments.

Higher Kinded Types

A higher kinded type composes type arguments to a new type. I use square bracket notation to define a higher kinded type:

C[T] // The higher kinded type `C` composes type argument `T` to a new type `C[T]`.

The same works with multiple type arguments:

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originally written in Dec 2011, needs updating

Log analysis has always struck me as one of those things that gets too much superficial attention without enough attention to detail. That is, we know that we need to do it, but we don’t talk about how we need to do it. At best, we talk about making sure we collect and archive logs. Analysis plays second fiddle, even though in reality logs without analysis provide almost no value to an organization. And you’ll find greatest value in discovery of the earliest stages of an incident rather than in hindsight to understand what went wrong. Unfortunately, less than 1% of data breach investigations in the 2011 Verizon DBIR started with log analysis and review!

The analysis ideas I present below don’t even begin to represent a comprehensive view. And of course every network is different, so you will need to think about your specific needs. But this may get

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Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

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Latency Comparison Numbers
--------------------------
L1 cache reference                           0.5 ns
Branch mispredict                            5   ns
L2 cache reference                           7   ns                      14x L1 cache
Mutex lock/unlock                           25   ns
Main memory reference                      100   ns                      20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy             3,000   ns        3 us
Send 1K bytes over 1 Gbps network       10,000   ns       10 us
Read 4K randomly from SSD*             150,000   ns      150 us          ~1GB/sec SSD

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Contents

• Why care about Rust?
• The Toolchain
• Creating a New Project
• Modules
• Crates
• Types
• References
• Mutability

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