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How important is the order of columns in indexes?
... 3, the optimizer wouldn't even use the index, because it's not helpful at all in narrowing down the result sets. Anytime you're in a query, narrowing down the number of results to deal with before the next step means better performance.
Since the index is also stored this way, there's no backtrac...
Can git automatically switch between spaces and tabs?
...global filter.tabspace.clean 'expand --tabs=4 --initial'
OS X
First install coreutils with brew:
brew install coreutils
Now run the commands:
git config --global filter.tabspace.smudge 'gunexpand --tabs=4 --first-only'
git config --global filter.tabspace.clean 'gexpand --tabs=4 --initial'
A...
What is CDATA in HTML? [duplicate]
...
All text in an XML document will be parsed by the parser.
But text inside a CDATA section will be ignored by the parser.
CDATA - (Unparsed) Character Data
The term CDATA is used about text data that should not be parsed by t...
Why is “except: pass” a bad programming practice?
...y to avoid passing in except blocks. Unless explicitly desired, this is usually not a good sign.
But let’s go into detail:
Don’t catch any error
When using a try block, you usually do this because you know that there is a chance of an exception being thrown. As such, you also already have an...
Combine two data frames by rows (rbind) when they have different sets of columns
...
@MERose Hadley: "Yes, all dplyr methods ignore rownames."
– zx8754
Dec 7 '17 at 9:11
...
Support for “border-radius” in IE
...es! When IE9 is released in Jan 2011.
Let's say you want an even 15px on all four sides:
.myclass {
border-style: solid;
border-width: 2px;
-moz-border-radius: 15px;
-webkit-border-radius: 15px;
border-radius: 15px;
}
IE9 will use the default border-radius, so just make sure you include th...
How to get nth jQuery element
...epends on the desired behavior. $('select').find('option').eq(n) will basically ignore the grouping, and get all options as a whole. If you want it per group, something like this is necessary: $('select').find('optgroup').each(function() { $(this).find('option').eq(n)...; })
– ...
clang: how to list supported target architectures?
Currently I am interested in ARM in general and specifically iphone/android targets. But I just want to know more about clang, since it feels to play important role in the years to come.
...
Why is “copy and paste” of code dangerous? [closed]
...you will need to fix it every place you did and hope you can remember them all (this also holds for changed requirements).
If you keep logic in one place, it is easier to change when needed (so if you decide that the application needs updating, you only do it in one place).
Have your boss read abo...
How does akka compare to Erlang? [closed]
... Camel, JAX-RS,
etc etc)
Erlang does the process
scheduling for you - Akka allows you
to use many different Dispatchers
with endless configuration
opportunities
Erlang does hot code
reload - Akka can support it, but
it's less flexible because of JVM
classloading
Those are the ones from the top of ...