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Is it a good idea to index datetime field in mysql?
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But if you query the data with date range, such as data range from "2017-01-01 11:20" to "2018-01-03 12:12", it doesn't make SELECT query faster even though I indexed date time column... index make query fast when I use equal operation.. Am i right?
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How to log cron jobs?
...hat there are special characters you can use for lists (commas), to define ranges (dashes -), to define increment of ranges (slashes), etc. Take a look:
http://www.softpanorama.org/Utilities/cron.shtml
share
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Append column to pandas dataframe
...ome interesting behavior of join and concat:
dat1 = pd.DataFrame({'dat1': range(4)})
dat2 = pd.DataFrame({'dat2': range(4,8)})
dat1.index = [1,3,5,7]
dat2.index = [2,4,6,8]
# way1 join 2 DataFrames
print(dat1.join(dat2))
# output
dat1 dat2
1 0 NaN
3 1 NaN
5 2 NaN
7 3 Na...
What is the fastest way to compute sin and cos together?
...sincos is not a complete implementation on its own; you need an additional range reduction step to put the argument into the valid input range for the fsincos instruction. The library sin and cos functions include this reduction as well as the core computation, so they are even faster (by compariso...
Map Tiling Algorithm
...n be effected by the color).
Pseudo code:
iterations = 5
for iteration in range(iterations):
for i in range(400):
for j in range(400):
try:
grid[i][j] = average(grid[i+1][j], grid[i-1][j],
grid[i][j+1], grid[i][j+1])
...
How could I use requests in asyncio?
...
'http://example.org/'
)
for i in range(20)
]
for response in await asyncio.gather(*futures):
pass
loop = asyncio.get_event_loop()
loop.run_until_complete(main())
...
How to drive C#, C++ or Java compiler to compute 1+2+3+…+1000 at compile time?
In a recent interview, I was asked a really strange question. The interviewer asked me how can I compute 1+2+3+...+1000 just using compiler features. This means that I am not allowed to write a program and execute it, but I should just write a program that could drive the compiler to compute this su...
How can I make setInterval also work when a tab is inactive in Chrome?
...ar startedAt, duration = 3000
var domain = [-100, window.innerWidth]
var range = domain[1] - domain[0]
function start() {
startedAt = Date.now()
updateTarget(0)
requestAnimationFrame(update)
}
function update() {
let elapsedTime = Date.now() - startedAt
// playback is a val...
How do I use itertools.groupby()?
...ion (see notebook)
Consecutive values over a threshold (see notebook)
Find ranges of numbers in a list or continuous items (see docs)
Find all related longest sequences
Take consecutive sequences that meet a condition (see related post)
Note: Several of the latter examples derive from Víctor Terr...
What is the difference between float and double?
...ision of 7 digits. While it may store values with very large or very small range (+/- 3.4 * 10^38 or * 10^-38), it has only 7 significant digits.
Type double, 64 bits long, has a bigger range (*10^+/-308) and 15 digits precision.
Type long double is nominally 80 bits, though a given compiler/OS pa...