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MongoDB: update every document on one field
I have a collected named foo hypothetically.
4 Answers
4
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Redis strings vs Redis hashes to represent JSON: efficiency?
I want to store a JSON payload into redis. There's really 2 ways I can do this:
3 Answers
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Difference: std::runtime_error vs std::exception()
... in the exception hierarchy. It has no other uses. In other words, conceptually it is an abstract class (even though it is not defined as abstract class in C++ meaning of the term).
std::runtime_error is a more specialized class, descending from std::exception, intended to be thrown in case of vari...
innerText vs innerHTML vs label vs text vs textContent vs outerText
... a couple of differences:
Note that while textContent gets the content of all elements, including <script> and <style> elements, the mostly equivalent IE-specific property, innerText, does not.
innerText is also aware of style and will not return the text of hidden elements, whereas te...
what's the difference between “hadoop fs” shell commands and “hdfs dfs” shell commands?
...s dfs instead.
hdfs dfs <args>
same as 2nd i.e would work for all the operations related to HDFS and is the recommended command instead of hadoop dfs
below is the list categorized as hdfs commands.
namenode|secondarynamenode|datanode|dfs|dfsadmin|fsck|balancer|fetchdt|oiv|dfsgroups
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JPA or JDBC, how are they different?
...sh for the same. I saw some examples and also read the Oracle docs to know all about Java EE 5. Connecting to a database was very simple. I opened a dynamic web project, created a session EJB , I used EntityManager and with the get methods could access the stored data table.
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Filter git diff by type of change
...de) changed
U Unmerged
X Unknown
B have had their pairing Broken
* All-or-none
Any combination of the filter characters may be used.
When * (All-or-none) is added to the combination, all paths are
selected if there is any file that matches other criteria in the
comparison; ...
Byte order mark screws up file reading in Java
...va. Some of the files may have a byte order mark in the beginning, but not all. When present, the byte order gets read along with the rest of the first line, thus causing problems with string compares.
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What is eager loading?
...hing when asked. Classic example is when you multiply two matrices. You do all the calculations. That's eager loading;
Lazy loading: you only do a calculation when required. In the previous example, you don't do any calculations until you access an element of the result matrix; and
Over-eager loadin...
postgresql return 0 if returned value is null
...ns the first of its arguments that is not null.
Null is returned only if all arguments are null. It is often
used to substitute a default value for null values when data is
retrieved for display.
Edit
Here's an example of COALESCE with your query:
SELECT AVG( price )
FROM(
SELECT *, cum...