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When to use Task.Delay, when to use Thread.Sleep?
...ary real-world use is as retry timers for I/O operations, which are on the order of seconds rather than milliseconds.
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What's faster, SELECT DISTINCT or GROUP BY in MySQL?
...he output, and GROUP BY by default does. However, in MySQL even a DISTINCT+ORDER BY might still be faster than a GROUP BY due to the extra hints for the optimizer as explained by SquareCog.
– rustyx
Jan 25 '15 at 15:03
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How to sort a HashMap in Java [duplicate]
... you're handed existing Maps and just want to iterate through them in some order. Also, the LinkedHashMap can maintain by insertion order (which I often like for debugging), or by access order. And finally if you're doing a lot of this you might check out Java 1.6 and NavigableMap, awesome stuff!
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What is the common header format of Python files?
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How unique is UUID?
...ely generate a batch of 16,384 UUIDs within the span of a single "tick" in order to overflow the sequence number. I have seen this happen with an implementation that relied, naively, on a clock source that (1) had μs-level granularity, and (2) was not guaranteed to be monotonic (system clocks are ...
When to use Comparable and Comparator
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Use Comparable if you want to define a default (natural) ordering behaviour of the object in question, a common practice is to use a technical or natural (database?) identifier of the object for this.
Use Comparator if you want to define an external controllable ordering behaviour...
Remove duplicate dict in list in Python
...ne of the tuples created from a dictionary
Edit: If you want to preserve ordering, the one-liner above won't work since set won't do that. However, with a few lines of code, you can also do that:
l = [{'a': 123, 'b': 1234},
{'a': 3222, 'b': 1234},
{'a': 123, 'b': 1234}]
seen = se...
Java 8 stream reverse order
...tores the elements into an array and reads them out to a stream in reverse order. Note that since we don't know the runtime type of the stream elements, we can't type the array properly, requiring an unchecked cast.
@SuppressWarnings("unchecked")
static <T> Stream<T> reverse(Stream<T...
Efficiently convert rows to columns in sql server
... yourtable
group by ColumnName, id
order by id
FOR XML PATH(''), TYPE
).value('.', 'NVARCHAR(MAX)')
,1,1,'')
set @query = N'SELECT ' + @cols + N' from
(
select value, ColumnName
fr...
The entity cannot be constructed in a LINQ to Entities query
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@Moshii just in order to satisfy the method return type signature, (as I said in the answer, it's not useful anymore).
– Soren
Jan 14 '17 at 5:32
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