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How important is the order of columns in indexes?
...should put columns that will be the most selective at the beginning of the index declaration. Example:
5 Answers
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Does MySQL index foreign key columns automatically?
Does MySQL index foreign key columns automatically?
9 Answers
9
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What is the difference between the remap, noremap, nnoremap and vnoremap mapping commands in Vim?
...rious mapping commands. What that means is that if you do:
:map j gg
:map Q j
:noremap W j
j will be mapped to gg. Q will also be mapped to gg, because j will be expanded for the recursive mapping. W will be mapped to j (and not to gg) because j will not be expanded for the non-recursive mapping....
What is normalized UTF-8 all about?
...input.
Canonical normalization comes in 2 forms: NFD and NFC. The two are equivalent in the sense that one can convert between these two forms without loss. Comparing two strings under NFC will always give the same result as comparing them under NFD.
NFD
NFD has the characters fully expanded out. Th...
Indexes of all occurrences of character in a string
...tions without the -1 at the end that Peter Lawrey's solution has had.
int index = word.indexOf(guess);
while (index >= 0) {
System.out.println(index);
index = word.indexOf(guess, index + 1);
}
It can also be done as a for loop:
for (int index = word.indexOf(guess);
index >= 0;...
Safe (bounds-checked) array lookup in Swift, through optional bindings?
If I have an array in Swift, and try to access an index that is out of bounds, there is an unsurprising runtime error:
19 A...
How to iterate for loop in reverse order in swift?
....
To iterate on a range in reverse order, they can be used as below:
for index in stride(from: 5, to: 1, by: -1) {
print(index)
}
//prints 5, 4, 3, 2
for index in stride(from: 5, through: 1, by: -1) {
print(index)
}
//prints 5, 4, 3, 2, 1
Note that neither of those is a Range member fun...
Check if a value exists in pandas dataframe index
...
This should do the trick
'g' in df.index
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How many database indexes is too many?
...that occur on the table.
If there's lots of SELECTs and very few changes, index all you like.... these will (potentially) speed the SELECT statements up.
If the table is heavily hit by UPDATEs, INSERTs + DELETEs ... these will be very slow with lots of indexes since they all need to be modified ea...
Finding index of character in Swift String
... one who couldn't find the solution.
String doesn't implement RandomAccessIndexType. Probably because they enable characters with different byte lengths. That's why we have to use string.characters.count (count or countElements in Swift 1.x) to get the number of characters. That also applies to pos...