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What's the difference between an exclusive lock and a shared lock?
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When the students are reading (shared locks) what is on the board:
They all can read what is on it, together => Multiple shared locks can co-exist.
The teacher waits for them to finish reading before she clears the board to write more => If one or more shared locks already exist, exclusive ...
return query based on date
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You probably want to make a range query, for example, all items created after a given date:
db.gpsdatas.find({"createdAt" : { $gte : new ISODate("2012-01-12T20:15:31Z") }});
I'm using $gte (greater than or equals), because this is often used for date-only queries, where the t...
In ASP.NET, when should I use Session.Clear() rather than Session.Abandon()?
...n and the Session_OnEnd event is triggered.
Session.Clear() just removes all values (content) from the Object. The session with the same key is still alive.
So, if you use Session.Abandon(), you lose that specific session and the user will get a new session key. You could use it for example when ...
How to suppress specific MSBuild warning
...ng (e.g. MSB3253) when running MSBuild from command line? My build script calls msbuild.exe much the following way:
5 Answe...
Numpy: Get random set of rows from 2D array
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11
This is a similar answer to the one Hezi Rasheff provided, but simplified so newer python users...
Big O of JavaScript arrays
...pending - Amortized O(1) (sometimes resizing the hashtable is required; usually only insertion is required)
Prepending - O(n) via unshift, since it requires reassigning all the indexes
Insertion - Amortized O(1) if the value does not exist. O(n) if you want to shift existing values (Eg, using splice...
Effect of NOLOCK hint in SELECT statements
...l complete faster than a normal select.
2) Yes, a select with NOLOCK will allow other queries against the effected table to complete faster than a normal select.
Why would this be?
NOLOCK typically (depending on your DB engine) means give me your data, and I don't care what state it is in, and d...
How to clear variables in ipython?
...nd I get bad surprises when variables haven't been cleared. How do I clear all variables?
And is it possible to force this somehow every time I invoke the magic command %run?
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Differences between Java 8 Date Time API (java.time) and Joda-Time
...s perfect ;-)).
c) With both libraries we get a real calendar date type (called LocalDate), a real wall time type (called LocalTime) and the composition (called LocalDateTime). That is a very big win compared with old java.util.Calendar and java.util.Date.
d) Both libraries use a method-centric ap...
Bash script processing limited number of commands in parallel
... the exit status of the last
command waited for. If a job spec is given, all processes in the job
are waited for. If no arguments are given, all currently active child
processes are waited for, and the return status is zero. If neither
jobspec nor pid specifies an active child process of the...