# Why fall sleep fast?

In the battle ground, if you don’t sleep, you’ll burn out pretty quickly. You’ll make bad decisions. You’ll let people down and become a liability.

# How to fall asleep in 120 seconds?

Principle: Relax the whole body one part by another and don’t think.

  1. Stretch out
  2. Relax face muscles and slow down everything
  3. Relax upper body
    1. Let shoulders drop as low as they can
    2. Breathe in deeply. Then exhale slowly, blowing out all of the tension
    3. Relax arms. If it’s not relaxing, tense it first, then let it go loose
    4. Relax fore arm
    5. Relax hand
  4. Relax legs
  5. Not think about anything
    1. keep your mind still. You can do this by holding a static image in your head
    2. If that doesn’t work, say the words “don’t think… don’t think… don’t think” over and over for at least 10 second

Disclaimer: I highly doubt those guys who succeed only by giving advice on how to succeed. A bird’s flight does not need the guidance of ornithologists. Anyhow, food for thought that these are what American women think helpful to their promotions.

  1. claim your achievements often
  2. realize that others will not notice and reward your contributions unless you say it
  3. expertise is not the only criteria
  4. leverage relationships
  5. enlist allies from day one
  6. put your career before your job
  7. don’t be a perfectionist
  8. kill the disease to please
  9. be relaxed and stretched out
  10. be less emotional, speak less, and disclose less
  11. move on effectively from failures
  12. be undistracted

# What are the challenges?

Before TAO, use cache-aside pattern

Before TAO

Social graph data is stored in MySQL and cached in Memcached

3 problems:

  1. list update operation in Memcached is inefficient. cannot append but update the whole list.
  2. clients have to manage cache
  3. Hard to offer read-after-write consistency

To solve those problems, we have 3 goals:

  • online data graph service that is efficiency at scale
  • optimize for read (its read-to-write ratio is 500:1)
    • low read latency
    • high read availability (eventual consistency)
  • timeliness of writes (read-after-write)

# Data Model

  • Objects (e.g. user, location, comment) with unique IDs
  • Associations (e.g. tagged, like, author) between two IDs
  • Both have key-value data as well as a time field

# Solutions: TAO

  1. Efficiency at scale and reduce read latency

  2. Write timeliness

    • write-through cache
    • follower/leader cache to solve thundering herd problem
    • async replication
  3. Read availability

    • Read Failover to alternate data sources

# TAO’s Architecture

  • MySQL databases → durability
  • Leader cache → coordinates writes to each object
  • Follower caches → serve reads but not writes. forward all writes to leader.

Facebook TAO Architecture

Read failover

Facebook TAO Read Failover

Why do startups have to innovate? Why do growth techniques work only once for a given product or service in a given market? Why is there no skill called “business”?

The answer is Anna Karenina principle. Tolstoy opens Anna Karenina by observing: “All happy families are alike; each unhappy family is unhappy in its own way.” Business is the opposite. All happy companies are different: each one earns a monopoly by solving a unique problem. All failed companies are the same: they failed to escape competition.

If a startup does not innovate but copy a product or service from the market leader, and the startup is targeting the same market, then people will not buy it because people are probably customers of the market leader already. Why do people buy the same thing for twice if their needs are fulfilled already?

What is a Market?

1256 2018-09-16 18:56

For high tech, we can define a market as

  1. a set of actual or potential customers
  2. for a given set of products or services
  3. who have a common set of needs or wants, and
  4. who reference each other when making a buying decision.

Point 4 is the insight here - referencing each other is key to the marketing success. If two people buy the same product for the same reason but have no way they could reference each other, they are not part of the same market. They are in different market segments.

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