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Rajkumar Singh rajkrrsingh

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View latency.markdown

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

@t3rmin4t0r
t3rmin4t0r / ats-extract-plan.py
Created Jun 30, 2015
ATS to Hive query plan extraction
View ats-extract-plan.py
import json
import sys
class ATSFile(object):
def __init__(self, name):
self.data = json.load(open(name))
self.name = name
def dump(self):
info = self.data["otherinfo"]
q = json.loads(info["QUERY"])