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Difference between volatile and synchronized in Java
...om obtaining the monitor (or lock) for the same object, thereby preventing all code blocks protected by synchronization on the same object from executing concurrently. Synchronization also creates a "happens-before" memory barrier, causing a memory visibility constraint such that anything done up t...
How do servlets work? Instantiation, sessions, shared variables and multithreading
... servlet container (like Apache Tomcat) starts up, it will deploy and load all its web applications. When a web application is loaded, the servlet container creates the ServletContext once and keeps it in the server's memory. The web app's web.xml and all of included web-fragment.xml files is parsed...
How do I see all foreign keys to a table or column?
In MySQL, how do I get a list of all foreign key constraints pointing to a particular table? a particular column? This is the same thing as this Oracle question , but for MySQL.
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How do I force “git pull” to overwrite local files?
... content), these files will not be affected.
First, run a fetch to update all origin/<branch> refs to latest:
git fetch --all
Then, you have two options:
git reset --hard origin/master
OR If you are on some other branch:
git reset --hard origin/<branch_name>
Explanation:
git fetch do...
How do I tell Maven to use the latest version of a dependency?
In Maven, dependencies are usually set up like this:
12 Answers
12
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Why does X[Y] join of data.tables not allow a full outer join, or a left join?
...Y) does both ways at the same time. The number of rows of X[Y] and Y[X] usually differ, whereas the number of rows returned by merge(X,Y) and merge(Y,X) is the same.
BUT that misses the main point. Most tasks require something to be done on the
data after a join or merge. Why merge all the co...
What is the most ridiculous pessimization you've seen? [closed]
We all know that premature optimization is the root of all evil because it leads to unreadable/unmaintainable code. Even worse is pessimization, when someone implements an "optimization" because they think it will be faster, but it ends up being slower, as well as being buggy, unmaintainable, etc...
All Ruby tests raising: undefined method `authenticate' for nil:NilClass
Most of my tests are raising the following and I don't understand why. All methods call raise the 'authenticate' error. I've checked the code if there was a method called "authenticate" but there is no such method.
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How to change identity column values programmatically?
...Y,
X VARCHAR(10)
)
INSERT INTO Test
OUTPUT INSERTED.*
SELECT 'Foo' UNION ALL
SELECT 'Bar' UNION ALL
SELECT 'Baz'
Then you can do
/*Define table with same structure but no IDENTITY*/
CREATE TABLE Temp
(
ID INT PRIMARY KEY,
X VARCHAR(10)
)
/*Switch table metadata to new structure*/
ALTER TABLE T...
Remove all multiple spaces in Javascript and replace with single space [duplicate]
How can I automatically replace all instances of multiple spaces, with a single space, in Javascript?
4 Answers
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