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postgresql COUNT(DISTINCT …) very slow
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Have you considered the effect of caching? If doing three "explain analyze" subsequently, the first one may be slow fetching things from disk while the two latter may be fast fetching from memory.
– tobixen
Jun 28 '12 at 18:45
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How do I delete an exported environment variable?
...variables you set in one terminal instance will not carry over to another. If you have a variable which seems to be set automatically every time you open terminal, try looking through the various hidden files in your home directory for it. Or, to see where it is being set, try "grep -r <X> ~" ...
What are the differences between the different saving methods in Hibernate?
..., when to use which, and why isn't there just one intelligent method that knows when to use what?
10 Answers
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What is the best way to conditionally apply a class?
...nditionally, like:
ng-class="{selected: $index==selectedIndex}"
Angular now supports expressions that return an object. Each property (name) of this object is now considered as a class name and is applied depending on its value.
However these ways are not functionally equal. Here is an example:
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bundle install fails with SSL certificate verification error
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Update
Now that I've karma wh..err mined enough from this answer everyone should know that this should have been fixed.
re: via Ownatik again bundle install fails with SSL certificate verification error
gem update --system
My an...
How to update Identity Column in SQL Server?
... it started
with a big number 10010 and it's related with another table, now I have 200 records and I want to fix this issue before the records increases.
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How to fix the datetime2 out-of-range conversion error using DbContext and SetInitializer?
...ime.MinValue (or equivalenly, default(DateTime)) is used to indicate an unknown value.
This simple extension method can help handle such situations:
public static class DbDateHelper
{
/// <summary>
/// Replaces any date before 01.01.1753 with a Nullable of
/// DateTime with a v...
Add Keypair to existing EC2 instance
...file system (still on instance-B):
sudo umount /vol-a
sudo rmdir /vol-a
Now, back on your system with ec2-api-tools, continue moving the EBS volume back to it’s home on the original instance A and start the instance again:
ec2-detach-volume $volume
ec2-attach-volume --instance $instance_a --de...
Effects of the extern keyword on C functions
...ar.c.
Here is foo.c
#include <stdio.h>
volatile unsigned int stop_now = 0;
extern void bar_function(void);
int main(void)
{
while (1) {
bar_function();
stop_now = 1;
}
return 0;
}
Now, here is bar.c
#include <stdio.h>
extern volatile unsigned int stop_now;
void b...
What are the alternatives now that the Google web search API has been deprecated? [closed]
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Yes, Google Custom Search has now replaced the old Search API, but you can still use Google Custom Search to search the entire web, although the steps are not obvious from the Custom Search setup.
To create a Google Custom Search engine that searches th...